Indian Railways - Rail Wheel Factory Report
SameerShah51
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About This Presentation
Indian Railways - Rail Wheel Factory Report
Slide Content
Internship
Project Report
Rail Wheel & Axle Manufacturing
Submitted by – Sameer Shah
Sir M. Visvesvaraya Institute of Technology
27 January 2015
Project Report
Rail Wheel & Axle Manufacturing
Submitted by – Sameer Shah
Sir M. Visvesvaraya Institute of Technology
27 January 2015
Table of Contents
Abstract
Acknowledgement
Indian Railways
History of RWF Yelahanka
New RWF logo
Wheel Shop
Controlled Pressure Pouring
Technique
Steel Melting Shop
Electric Arc Furnace
Cast Wheel Processing
Wheel Final Processing Shop
Axle Shop
Forging Shop
Machining Shop
Ultrasonic Testing
Wheel Assembly Shop
Programmable Logic Controller
Bibliography
Abstract
Acknowledgement
Indian Railways
History of RWF Yelahanka
New RWF logo
Wheel Shop
Controlled Pressure Pouring
Technique
Steel Melting Shop
Electric Arc Furnace
Cast Wheel Processing
Wheel Final Processing Shop
Axle Shop
Forging Shop
Machining Shop
Ultrasonic Testing
Wheel Assembly Shop
Programmable Logic Controller
Bibliography
Internship Training Report
On Rail Wheel and Axle Manufacturing
Submitted by
Sameer Shah (1MV13ME123)
Student of Bachelor of Engineering in Mechanical Engineering
Sir M. Visvesvaraya Institute of Technology, Bangalore
Internship training undertaken at
Rail Wheel Factory, Yelahanka
On Rail Wheel and Axle Manufacturing
Submitted by
Sameer Shah (1MV13ME123)
Student of Bachelor of Engineering in Mechanical Engineering
Sir M. Visvesvaraya Institute of Technology, Bangalore
Internship training undertaken at
Rail Wheel Factory, Yelahanka
ABSTRACT
The internship program at Rail Wheel Factory requires that each intern conducts
an industrial visit and factory tours in their area of engineering and submits a
report on it in consultation with the faculty members supervising the same. The
internship report is included in the curriculum with a view to synthesise the
knowledge gathered during the two weeks period credited by the intern during
the internship program at RWF Yelahanka. Creating a report of the project is part
of the training of skill building of the student on of technical communication.
Here the emphasis is on presenting a technical matter in an objective written
form.
This document is a record of the requirements for preparation of the internship
project submitted at the end of the training program. It prescribes typical
contents that a Project Report usually should contain, and provides the format of
its presentation. Some guidelines are mandatory to follow during the
preparation of the report, while the others help in improving the presentation of
the work accomplished in the project.
The following project report shows the detailed casting procedure for railway
wheels and forging procedure for axles which are produced by RWF for Indian
Railways.
The internship program at Rail Wheel Factory requires that each intern conducts
an industrial visit and factory tours in their area of engineering and submits a
report on it in consultation with the faculty members supervising the same. The
internship report is included in the curriculum with a view to synthesise the
knowledge gathered during the two weeks period credited by the intern during
the internship program at RWF Yelahanka. Creating a report of the project is part
of the training of skill building of the student on of technical communication.
Here the emphasis is on presenting a technical matter in an objective written
form.
This document is a record of the requirements for preparation of the internship
project submitted at the end of the training program. It prescribes typical
contents that a Project Report usually should contain, and provides the format of
its presentation. Some guidelines are mandatory to follow during the
preparation of the report, while the others help in improving the presentation of
the work accomplished in the project.
The following project report shows the detailed casting procedure for railway
wheels and forging procedure for axles which are produced by RWF for Indian
Railways.
Acknowledgement
I sincerely want to thank our Officers, Supervisors and Staff of Rail Wheel Factory
Yelahanka for their kind support. This industrial training would not have been
possible without them.
Firstly, I would like to thank Mr S. N. Sarkar / Dy.CME/TQM & Principal / TTC who
gave us this wonderful opportunity to do Internship at Rail Wheel Factory
Yelahanka. I would also like to express our gratitude to Mr T.
Suresha/SSE/TTC/Electrical, Mr. M.G. Sunil/SSE/TTC/Mechanical, Mr. D. Sanjeev
Rao/SSE/TTC/Mechanical, Mr. Rahul Ragavendra/ Trainee SSE and last but not
the least Mr. CHRISPIN V.L/Trainee SSE, for sharing literature and invaluable
technical support during this training.
Secondly I would like to thank Dr. N Govinda Raju (Professor, Head of Dept
Mechanical Engineering and Director-Research) who granted me permission to
do this Internship.
I also would like to thank all the operators in shop floor of RWF who took out
their valuable time and guided us and helped us complete this training.
Lastly, I would like to thank my parents for their kind support and those who
have directly and directly helped us to complete this Internship successfully.
I sincerely want to thank our Officers, Supervisors and Staff of Rail Wheel Factory
Yelahanka for their kind support. This industrial training would not have been
possible without them.
Firstly, I would like to thank Mr S. N. Sarkar / Dy.CME/TQM & Principal / TTC who
gave us this wonderful opportunity to do Internship at Rail Wheel Factory
Yelahanka. I would also like to express our gratitude to Mr T.
Suresha/SSE/TTC/Electrical, Mr. M.G. Sunil/SSE/TTC/Mechanical, Mr. D. Sanjeev
Rao/SSE/TTC/Mechanical, Mr. Rahul Ragavendra/ Trainee SSE and last but not
the least Mr. CHRISPIN V.L/Trainee SSE, for sharing literature and invaluable
technical support during this training.
Secondly I would like to thank Dr. N Govinda Raju (Professor, Head of Dept
Mechanical Engineering and Director-Research) who granted me permission to
do this Internship.
I also would like to thank all the operators in shop floor of RWF who took out
their valuable time and guided us and helped us complete this training.
Lastly, I would like to thank my parents for their kind support and those who
have directly and directly helped us to complete this Internship successfully.
INDIAN RAILWAYS
Indian Railways is an Indian state-owned enterprise,
owned and operated by the Government of India through the Ministry of
Railways. It is one of the world's largest railway networks comprising 115,000 km
(71,000 mi) of track over a route of 65,808 km (40,891 mi) and 7,112 stations. In
2014-15, IR carried 8.397 billion passengers annually or more than 23 million
passengers a day (roughly half of whom were suburban passengers) and 1058.81
million tons of freight in the year. In 2014–2015 Indian Railways had revenues of
₹1634.50 billion (US$24 billion) which consists of ₹1069.27 billion (US$16 billion)
from freight and ₹402.80 billion (US$6.0 billion) from passengers tickets.
Railways were first introduced to India in the year 1853 from Mumbai to Thane.
In 1951 the systems were nationalised as one unit, the Indian Railways,
becoming one of the largest networks in the world. IR operates both long
distance and suburban rail systems on a multi-gauge network of broad, metre
and narrow gauges. It also owns locomotive and coach production facilities at
several places in India and are assigned codes identifying their gauge, kind of
power and type of operation. Its operations cover twenty nine states and seven
union territories and also provide limited international services to Nepal,
Bangladesh and Pakistan.
Railways are the world's seventh largest commercial or utility employer, by
number of employees, with over 1.376 million employees as of last published
figures in 2013. As for rolling stock, IR holds over 245,267 Freight Wagons,
66,392 Passenger Coaches and 10,499 Locomotives (43 steam, 5,633 diesel and
4,823 electric locomotives).
The trains have a 5 digit numbering system and runs
12,617 passenger trains and 7421 freight trains daily. As of 31 March 2013,
21,614 km (13,430 mi) (32.8%) of the total 65,808 km (40,891 mi) route length
was electrified. Since 1960, almost all electrified sections on IR use 25,000 Volt
AC traction through overhead catenary delivery.
Indian Railways is an Indian state-owned enterprise,
owned and operated by the Government of India through the Ministry of
Railways. It is one of the world's largest railway networks comprising 115,000 km
(71,000 mi) of track over a route of 65,808 km (40,891 mi) and 7,112 stations. In
2014-15, IR carried 8.397 billion passengers annually or more than 23 million
passengers a day (roughly half of whom were suburban passengers) and 1058.81
million tons of freight in the year. In 2014–2015 Indian Railways had revenues of
₹1634.50 billion (US$24 billion) which consists of ₹1069.27 billion (US$16 billion)
from freight and ₹402.80 billion (US$6.0 billion) from passengers tickets.
Railways were first introduced to India in the year 1853 from Mumbai to Thane.
In 1951 the systems were nationalised as one unit, the Indian Railways,
becoming one of the largest networks in the world. IR operates both long
distance and suburban rail systems on a multi-gauge network of broad, metre
and narrow gauges. It also owns locomotive and coach production facilities at
several places in India and are assigned codes identifying their gauge, kind of
power and type of operation. Its operations cover twenty nine states and seven
union territories and also provide limited international services to Nepal,
Bangladesh and Pakistan.
Railways are the world's seventh largest commercial or utility employer, by
number of employees, with over 1.376 million employees as of last published
figures in 2013. As for rolling stock, IR holds over 245,267 Freight Wagons,
66,392 Passenger Coaches and 10,499 Locomotives (43 steam, 5,633 diesel and
4,823 electric locomotives).
The trains have a 5 digit numbering system and runs
12,617 passenger trains and 7421 freight trains daily. As of 31 March 2013,
21,614 km (13,430 mi) (32.8%) of the total 65,808 km (40,891 mi) route length
was electrified. Since 1960, almost all electrified sections on IR use 25,000 Volt
AC traction through overhead catenary delivery.
HISTORY OF RWF YELAHANKA
The cost of imports was high with prices rising in the world market. Financing
of imports, delays in supplies and limited availability of foreign exchange
adversely affected wagon production and rolling stock maintenance. It was in
this context that in the early 1970s the Railway Ministry felt the necessity for
setting up a new specialized Production Unit for manufacture of rolling stock
wheels and axles as import substitute. The ultimate objective was that DSP and
the Rail Wheel Factory should be able to totally meet Indian Railways
requirement for standard wheels and axles so that their import could be
stopped. Till early 1980s Indian Railways was importing about 55% of
requirement of wheels and axles. Indigenous capacity was available only at
Tata Iron & Steel Company [TISCO] and Durgapur Steel Plant [DSP]. The TISCO
plant was technocally not capable of meeting the changing requirement of
wheels and axles for the new designs of rolling stock and production was
discontinued. DSP was only able to partially meet Indian Railways’ needs.
Rail Wheel Factory (earlier known as Wheel and Axle Plant) is situated in
Bangalore, India. It is a state-of-the-art plant, meeting bulk of the requirement
of wheels, axles and wheel sets for the Indian Railways. The spare capacity
available is profitably utilised to meet the domestic demands for non-railway
customers and exports. RWF strives to build successful and lasting
relationships with its customers by consistently exceeding their expectations.
Customer focus and quality remain their watchwords. The plant is certified to
ISO-9001: 2008 and ISO-14001: 2004 standards by M/s. IRQS. It is also certified
to confirm to the Quality Assurance Program of Association of American
Railroads (AAR) in respect of manufacture of new wheels and axles.
All products are subjected to stage and final inspection, starting from the
chemical composition of the molten metal till the final inspection. This includes
micro/macro properties of the material, Magnetic Particle Testing, Ultrasonic
Testing, Hardness, warpage, dimensional parameters, surface finish etc.
All the products are accompanied with a Quality Assurance Certificate and carry
a warranty of one year from shipment. RWF has the full capability to design and
manufacture any size of wheels, axles and wheel sets to suit individual
customer’s special requirements.
The cost of imports was high with prices rising in the world market. Financing
of imports, delays in supplies and limited availability of foreign exchange
adversely affected wagon production and rolling stock maintenance. It was in
this context that in the early 1970s the Railway Ministry felt the necessity for
setting up a new specialized Production Unit for manufacture of rolling stock
wheels and axles as import substitute. The ultimate objective was that DSP and
the Rail Wheel Factory should be able to totally meet Indian Railways
requirement for standard wheels and axles so that their import could be
stopped. Till early 1980s Indian Railways was importing about 55% of
requirement of wheels and axles. Indigenous capacity was available only at
Tata Iron & Steel Company [TISCO] and Durgapur Steel Plant [DSP]. The TISCO
plant was technocally not capable of meeting the changing requirement of
wheels and axles for the new designs of rolling stock and production was
discontinued. DSP was only able to partially meet Indian Railways’ needs.
Rail Wheel Factory (earlier known as Wheel and Axle Plant) is situated in
Bangalore, India. It is a state-of-the-art plant, meeting bulk of the requirement
of wheels, axles and wheel sets for the Indian Railways. The spare capacity
available is profitably utilised to meet the domestic demands for non-railway
customers and exports. RWF strives to build successful and lasting
relationships with its customers by consistently exceeding their expectations.
Customer focus and quality remain their watchwords. The plant is certified to
ISO-9001: 2008 and ISO-14001: 2004 standards by M/s. IRQS. It is also certified
to confirm to the Quality Assurance Program of Association of American
Railroads (AAR) in respect of manufacture of new wheels and axles.
All products are subjected to stage and final inspection, starting from the
chemical composition of the molten metal till the final inspection. This includes
micro/macro properties of the material, Magnetic Particle Testing, Ultrasonic
Testing, Hardness, warpage, dimensional parameters, surface finish etc.
All the products are accompanied with a Quality Assurance Certificate and carry
a warranty of one year from shipment. RWF has the full capability to design and
manufacture any size of wheels, axles and wheel sets to suit individual
customer’s special requirements.
About the New logo
The new RWF emblem consists of a circular shell divided into two
parts. The top half is in green to represent productivity and energy,
featuring a Wheel / Axle combination symbol prominently. The bottom
half is blue in colour to represent sky infinity, opportunity and
confidence, featuring a modern diesel-hauled freight train rolling on
the wheel/axle units of type of manufacture by RWF.
The circular shield has a thick yellow border bearing the full
name of unit-in Hindi on top and in English at the bottom. The golden
yellow colour represents optimism and auspiciousness. Below the
shield is a symmetrical, three-fold ribbon with the central base in red-
representing passion and courage. On the red base is written “1984” in
bold white letters, marking the years of commencement of the unit.
The ribbon curls upwards on the other side, which is in blue-once
gain evoking the sky, infinity, opportunity and confidence. On the curl
on the either side is written the unit’s slogan in Hindi and English on
the left and right respectively.
In all, the new RWF emblem is configured along the line of
traditional heraldic symbols, invoking the finest traditions of valour
and honour.
The new RWF emblem consists of a circular shell divided into two
parts. The top half is in green to represent productivity and energy,
featuring a Wheel / Axle combination symbol prominently. The bottom
half is blue in colour to represent sky infinity, opportunity and
confidence, featuring a modern diesel-hauled freight train rolling on
the wheel/axle units of type of manufacture by RWF.
The circular shield has a thick yellow border bearing the full
name of unit-in Hindi on top and in English at the bottom. The golden
yellow colour represents optimism and auspiciousness. Below the
shield is a symmetrical, three-fold ribbon with the central base in red-
representing passion and courage. On the red base is written “1984” in
bold white letters, marking the years of commencement of the unit.
The ribbon curls upwards on the other side, which is in blue-once
gain evoking the sky, infinity, opportunity and confidence. On the curl
on the either side is written the unit’s slogan in Hindi and English on
the left and right respectively.
In all, the new RWF emblem is configured along the line of
traditional heraldic symbols, invoking the finest traditions of valour
and honour.
WHEEL SHOP
This is a sub unit of RWF which manufactures rail wheels by means of Controlled
Pressure Pouring Technique. These wheels are later assembled to axels and are
used to carry loads at high speeds.
At RWF the wheel shop is divided into 3 parts:-
Melting shop
Casting shop
Final processing shop
Controlled Pressure Pouring Technique
It is a method of accurately and automatically controlling the rate at which
molten metal is introduced into a mould during a pressure casting operation.
The basic idea of pressure casting is to force molten metal, against the force of
gravity, from a container through a pouring tube and mould gate into a casting
cavity of a mould by the application of pneumatic pressure fluid, such as
compressed air or other gas, against the metal in the container.
Because the rate of flow of the metal, against the force of gravity, from the
container or tank to the mould is dependent upon the application of super-
atmospheric fluid pressure upon the metal in the tank, accurate control of the
applied pressure is highly essential to a successful pressure casting operation.
Pressure Pouring Technique. These wheels are later assembled to axels and are
used to carry loads at high speeds.
At RWF the wheel shop is divided into 3 parts:-
Melting shop
Casting shop
Final processing shop
Controlled Pressure Pouring Technique
It is a method of accurately and automatically controlling the rate at which
molten metal is introduced into a mould during a pressure casting operation.
The basic idea of pressure casting is to force molten metal, against the force of
gravity, from a container through a pouring tube and mould gate into a casting
cavity of a mould by the application of pneumatic pressure fluid, such as
compressed air or other gas, against the metal in the container.
Because the rate of flow of the metal, against the force of gravity, from the
container or tank to the mould is dependent upon the application of super-
atmospheric fluid pressure upon the metal in the tank, accurate control of the
applied pressure is highly essential to a successful pressure casting operation.
Steel Melting shop
The wheel shop needs molten metal to carry out the casting process, the raw
materials used is scrap materials. It is melted in the furnace and used for casting.
Scrap management
The scrap used at RWF is used wheels and axles, used pieces of metal from
bogies and railway tracks. This scrap is picked with the help of electromagnetic
crane and dumped into the crucible.
Charging of furnace
The furnace is filled with scrap materials along with charge. Charge is an
additional material added to impart special properties. It is of 2 types
Ferrous charge
Ferrous charge consists of railway full wheels and scrap material like old used
wheels, axles, bogie compartments and rail tracks. Recently off cuts of plates
and sheets from ICF are also available. Condemned rails cut to 300 mm length
max are also used. Ferrous scrap should be free of dirt material and oil/grease,
rubber items. Oil/grease and rubber items contain high sulphur. Hence adequate
caution should be given before using scrap from diesel sheds and diesel POH shops.
Cast iron scraps (high Phosphorous and Sulphur) and springs (having high
Chromium) should be taken out from LMS.
Non-Ferrous charge
calcined lime 1000 to 1100 kg
graphite powder 150 to 230 kg
dolomite 200 kg
The electric arc furnace has an inbuilt transformer which steps down the input
power (11000 Volts/**) to (440 Volts / 25000 A). The furnace requires a large
amount of current to melt the scrap.
Re-carburising of metal:
Keep the required quantity of graphite powder ready in small quantities, filled in
gunny bag; maintain the bath temperature around 1640 Celsius minimum.
Lower the electrode column into the molten bath, such that the electrode is just
inside the bath. Introduce the graphite powder into the molten bath, near the
electrode column through the slag door.
The wheel shop needs molten metal to carry out the casting process, the raw
materials used is scrap materials. It is melted in the furnace and used for casting.
Scrap management
The scrap used at RWF is used wheels and axles, used pieces of metal from
bogies and railway tracks. This scrap is picked with the help of electromagnetic
crane and dumped into the crucible.
Charging of furnace
The furnace is filled with scrap materials along with charge. Charge is an
additional material added to impart special properties. It is of 2 types
Ferrous charge
Ferrous charge consists of railway full wheels and scrap material like old used
wheels, axles, bogie compartments and rail tracks. Recently off cuts of plates
and sheets from ICF are also available. Condemned rails cut to 300 mm length
max are also used. Ferrous scrap should be free of dirt material and oil/grease,
rubber items. Oil/grease and rubber items contain high sulphur. Hence adequate
caution should be given before using scrap from diesel sheds and diesel POH shops.
Cast iron scraps (high Phosphorous and Sulphur) and springs (having high
Chromium) should be taken out from LMS.
Non-Ferrous charge
calcined lime 1000 to 1100 kg
graphite powder 150 to 230 kg
dolomite 200 kg
The electric arc furnace has an inbuilt transformer which steps down the input
power (11000 Volts/**) to (440 Volts / 25000 A). The furnace requires a large
amount of current to melt the scrap.
Re-carburising of metal:
Keep the required quantity of graphite powder ready in small quantities, filled in
gunny bag; maintain the bath temperature around 1640 Celsius minimum.
Lower the electrode column into the molten bath, such that the electrode is just
inside the bath. Introduce the graphite powder into the molten bath, near the
electrode column through the slag door.
Push the cake fallen on door inside the furnace metal bath by rabble. Put on the
powder in whichever tap is required. After 3-4 minutes of arcing, mix the bath
thoroughly using metallic rabbles. Insure that the bath is uniform and no graphite
powder is floating on the top of the bath. Take the sample with the slag pre coated
spoon from deep inside the bath. After 3-4 min take one more sample in the similar
way.
Decarburising of metal:
The temperature of the metal must be maintained around 1630-1640 Celsius.
Coat the front end of oxygen pipe with furnace slag. Insert the slag coated
oxygen lancing pipe into the bath through the slag door and blow the bath with
oxygen at 5-6kg/cm depending on the carbon to be reduced. After the oxygen
blowing add 10-15kg of Ferro silicon to take care of high oxidised metal, when
necessary. Add 30-40kgs of Ferro manganese or silicon manganese to raise
manganese level in the bath and to take care of extra oxygen in the metal. Put on
power. Mix the bath thoroughly with the rabble. After 3-4 min of arcing, take the
sample from deep inside the bath for test. Again after 3-4 min take another
check sample. The ladles are then taken into JMP from where the metal is
poured into the cope and drag assembly for casting.
Electric arc furnace
An electric arc furnace (EAF) is a furnace that heats charged material by means of
an electric arc. Industrial arc furnaces range in size from small units of
approximately one ton capacity (used in foundries for producing cast
iron products) up to about 400 ton units used for secondary steelmaking. Arc
furnaces used in research laboratories and by dentists may have a capacity of
only a few dozen grams. Industrial electric arc furnace temperatures can be up to
1,800 °C (3,272 °F), while laboratory units can exceed 3,000 °C (5,432 °F).
Arc furnaces differ from induction furnaces in that the charge material is directly
exposed to an electric arc, and the current in the furnace terminals passes
through the charged material.
powder in whichever tap is required. After 3-4 minutes of arcing, mix the bath
thoroughly using metallic rabbles. Insure that the bath is uniform and no graphite
powder is floating on the top of the bath. Take the sample with the slag pre coated
spoon from deep inside the bath. After 3-4 min take one more sample in the similar
way.
Decarburising of metal:
The temperature of the metal must be maintained around 1630-1640 Celsius.
Coat the front end of oxygen pipe with furnace slag. Insert the slag coated
oxygen lancing pipe into the bath through the slag door and blow the bath with
oxygen at 5-6kg/cm depending on the carbon to be reduced. After the oxygen
blowing add 10-15kg of Ferro silicon to take care of high oxidised metal, when
necessary. Add 30-40kgs of Ferro manganese or silicon manganese to raise
manganese level in the bath and to take care of extra oxygen in the metal. Put on
power. Mix the bath thoroughly with the rabble. After 3-4 min of arcing, take the
sample from deep inside the bath for test. Again after 3-4 min take another
check sample. The ladles are then taken into JMP from where the metal is
poured into the cope and drag assembly for casting.
Electric arc furnace
An electric arc furnace (EAF) is a furnace that heats charged material by means of
an electric arc. Industrial arc furnaces range in size from small units of
approximately one ton capacity (used in foundries for producing cast
iron products) up to about 400 ton units used for secondary steelmaking. Arc
furnaces used in research laboratories and by dentists may have a capacity of
only a few dozen grams. Industrial electric arc furnace temperatures can be up to
1,800 °C (3,272 °F), while laboratory units can exceed 3,000 °C (5,432 °F).
Arc furnaces differ from induction furnaces in that the charge material is directly
exposed to an electric arc, and the current in the furnace terminals passes
through the charged material.
Construction
A schematic cross section through an EAF. Three electrodes (yellow), molten
bath (gold), tapping spout at left, refractory brick movable roof, brick shell and a
refractory lined bowl-shaped hearth.
An electric arc furnace used for steelmaking consists of a refractory-lined vessel,
usually water-cooled in larger sizes, covered with a retractable roof, and through
which one or more graphite electrodes enter the furnace. The furnace is
primarily split into three sections:
the shell, which consists of the sidewalls and lower steel "bowl";
the hearth, which consists of the refractory that lines the lower bowl;
The roof, which may be refractory-lined or water-cooled, and can be shaped
as a section of a sphere, or as a frustum (conical section). The roof also
supports the refractory delta in its centre, through which one or
more graphite electrodes enter.
The hearth may be hemispherical in shape, or in an eccentric bottom tapping
furnace (see below), the hearth has the shape of a halved egg. In modern
meltshops, the furnace is often raised off the ground floor, so that ladles and slag
pots can easily be maneuvered under either end of the furnace. Separate from
the furnace structure is the electrode support and electrical system, and the
tilting platform on which the furnace rests. Two configurations are possible: the
electrode supports and the roof tilt with the furnace, or are fixed to the raised
platform.
A schematic cross section through an EAF. Three electrodes (yellow), molten
bath (gold), tapping spout at left, refractory brick movable roof, brick shell and a
refractory lined bowl-shaped hearth.
An electric arc furnace used for steelmaking consists of a refractory-lined vessel,
usually water-cooled in larger sizes, covered with a retractable roof, and through
which one or more graphite electrodes enter the furnace. The furnace is
primarily split into three sections:
the shell, which consists of the sidewalls and lower steel "bowl";
the hearth, which consists of the refractory that lines the lower bowl;
The roof, which may be refractory-lined or water-cooled, and can be shaped
as a section of a sphere, or as a frustum (conical section). The roof also
supports the refractory delta in its centre, through which one or
more graphite electrodes enter.
The hearth may be hemispherical in shape, or in an eccentric bottom tapping
furnace (see below), the hearth has the shape of a halved egg. In modern
meltshops, the furnace is often raised off the ground floor, so that ladles and slag
pots can easily be maneuvered under either end of the furnace. Separate from
the furnace structure is the electrode support and electrical system, and the
tilting platform on which the furnace rests. Two configurations are possible: the
electrode supports and the roof tilt with the furnace, or are fixed to the raised
platform.
The roof of an arc furnace removed, showing the three electrodes
A typical alternating current furnace is powered by a three-phase electrical
supply and therefore has three electrodes. Electrodes are round in section, and
typically in segments with threaded couplings, so that as the electrodes wear,
new segments can be added. The arc forms between the charged material and
the electrode, the charge is heated both by current passing through the charge
and by the radiant energy evolved by the arc. The electrodes are automatically
raised and lowered by a positioning system, which may use either
electric winch hoists or hydraulic cylinders. The regulating system maintains
approximately constant current and power input during the melting of the
charge, even though scrap may move under the electrodes as it melts. The mast
arms holding the electrodes can either carry heavy busbars (which may be
hollow water-cooled copper pipes carrying current to the electrode clamps) or
be "hot arms", where the whole arm carries the current, increasing efficiency.
Hot arms can be made from copper-clad steel or aluminium. Since the electrodes
move up and down automatically for regulation of the arc, and are raised to
allow removal of the furnace roof, large water-cooled cables connect the bus
tubes/arms with the transformer located adjacent to the furnace. To protect the
transformer from heat, it is installed in a vault and is itself cooled via pumped oil
exchanging heat with the plant's water-cooling systems, as the electrical
conditions for arc-furnace steelmaking are extremely stressful on the
transformer.
The furnace is built on a tilting platform so that the liquid steel can be poured
into another vessel for transport. The operation of tilting the furnace to pour
molten steel is called "tapping". Originally, all steelmaking furnaces had a tapping
spout closed with refractory that washed out when the furnace was tilted, but
often modern furnaces have an eccentric bottom tap-hole (EBT) to reduce
inclusion of nitrogen andslag in the liquid steel. These furnaces have a taphole
that passes vertically through the hearth and shell, and is set off-centre in the
narrow "nose" of the egg-shaped hearth. It is filled with refractory sand, such
as olivine, when it is closed off. Modern plants may have two shells with a single
set of electrodes that can be transferred between the two; one shell preheats
scrap while the other shell is utilised for meltdown. Other DC-based furnaces
A typical alternating current furnace is powered by a three-phase electrical
supply and therefore has three electrodes. Electrodes are round in section, and
typically in segments with threaded couplings, so that as the electrodes wear,
new segments can be added. The arc forms between the charged material and
the electrode, the charge is heated both by current passing through the charge
and by the radiant energy evolved by the arc. The electrodes are automatically
raised and lowered by a positioning system, which may use either
electric winch hoists or hydraulic cylinders. The regulating system maintains
approximately constant current and power input during the melting of the
charge, even though scrap may move under the electrodes as it melts. The mast
arms holding the electrodes can either carry heavy busbars (which may be
hollow water-cooled copper pipes carrying current to the electrode clamps) or
be "hot arms", where the whole arm carries the current, increasing efficiency.
Hot arms can be made from copper-clad steel or aluminium. Since the electrodes
move up and down automatically for regulation of the arc, and are raised to
allow removal of the furnace roof, large water-cooled cables connect the bus
tubes/arms with the transformer located adjacent to the furnace. To protect the
transformer from heat, it is installed in a vault and is itself cooled via pumped oil
exchanging heat with the plant's water-cooling systems, as the electrical
conditions for arc-furnace steelmaking are extremely stressful on the
transformer.
The furnace is built on a tilting platform so that the liquid steel can be poured
into another vessel for transport. The operation of tilting the furnace to pour
molten steel is called "tapping". Originally, all steelmaking furnaces had a tapping
spout closed with refractory that washed out when the furnace was tilted, but
often modern furnaces have an eccentric bottom tap-hole (EBT) to reduce
inclusion of nitrogen andslag in the liquid steel. These furnaces have a taphole
that passes vertically through the hearth and shell, and is set off-centre in the
narrow "nose" of the egg-shaped hearth. It is filled with refractory sand, such
as olivine, when it is closed off. Modern plants may have two shells with a single
set of electrodes that can be transferred between the two; one shell preheats
scrap while the other shell is utilised for meltdown. Other DC-based furnaces
have a similar arrangement, but have electrodes for each shell and one set of
electronics.
AC furnaces usually exhibit a pattern of hot and cold-spots around the hearth
perimeter, with the cold-spots located between the electrodes. Modern furnaces
mount oxygen-fuel burners in the sidewall and use them to provide chemical
energy to the cold-spots, making the heating of the steel more uniform.
Additional chemical energy is provided by injecting oxygen and carbon into the
furnace; historically this was done through lances in the slag door, now this is
mainly done through multiple wall-mounted injection units that combine the
oxygen-fuel burners and the oxygen or carbon injection systems into one unit.
A mid-sized modern steelmaking furnace would have a transformer rated about
60,000,000 volt-amperes (60 MVA), with a secondary voltage between 400 and
900 volts and a secondary current in excess of 44,000 amperes. In a modern shop
such a furnace would be expected to produce a quantity of 80 metric tonnes of
liquid steel in approximately 50 minutes from charging with cold scrap to tapping
the furnace. In comparison, basic oxygen furnaces can have a capacity of 150–
300 tonnes per batch, or "heat", and can produce a heat in 30–40 minutes.
Enormous variations exist in furnace design details and operation, depending on
the end product and local conditions, as well as ongoing research to improve
furnace efficiency. The largest scrap-only furnace (in terms of tapping weight and
transformer rating) is a DC furnace operated by Tokyo Steel in Japan, with a tap
weight of 420 metric tonnes and fed by eight 32MVA transformers for 256MVA
total power.
To produce a ton of steel in an electric arc furnace requires approximately
400 kilowatt-hours per short ton or about 440 kWh per metric tonne; the
theoretical minimum amount of energy required to melt a tonne of scrap steel is
300 kWh (melting point 1520°C/2768°F). Therefore, a 300-tonne, 300 MVA EAF
will require approximately 132 MWh of energy to melt the steel, and a "power-
on time" (the time that steel is being melted with an arc) of approximately 37
minutes. Electric arc steelmaking is only economical where there is plentiful
electricity, with a well-developed electrical grid. In many locations, mills operate
during off-peak hours when utilities have surplus power generating capacity and
the price of electricity is less.
Electrodes
There are 3 non consumable graphite electrodes used in one electric arc
furnace.
They are connected to 3 phase power supply (6.6 kV)
There should be a 6-7 inches gap between the electrodes and scrap to
ensure proper arcing.
If the gap between the electrodes and scrap is large, proper arcing will not
take place. And if the gap is very small, the air between the electrodes and
electronics.
AC furnaces usually exhibit a pattern of hot and cold-spots around the hearth
perimeter, with the cold-spots located between the electrodes. Modern furnaces
mount oxygen-fuel burners in the sidewall and use them to provide chemical
energy to the cold-spots, making the heating of the steel more uniform.
Additional chemical energy is provided by injecting oxygen and carbon into the
furnace; historically this was done through lances in the slag door, now this is
mainly done through multiple wall-mounted injection units that combine the
oxygen-fuel burners and the oxygen or carbon injection systems into one unit.
A mid-sized modern steelmaking furnace would have a transformer rated about
60,000,000 volt-amperes (60 MVA), with a secondary voltage between 400 and
900 volts and a secondary current in excess of 44,000 amperes. In a modern shop
such a furnace would be expected to produce a quantity of 80 metric tonnes of
liquid steel in approximately 50 minutes from charging with cold scrap to tapping
the furnace. In comparison, basic oxygen furnaces can have a capacity of 150–
300 tonnes per batch, or "heat", and can produce a heat in 30–40 minutes.
Enormous variations exist in furnace design details and operation, depending on
the end product and local conditions, as well as ongoing research to improve
furnace efficiency. The largest scrap-only furnace (in terms of tapping weight and
transformer rating) is a DC furnace operated by Tokyo Steel in Japan, with a tap
weight of 420 metric tonnes and fed by eight 32MVA transformers for 256MVA
total power.
To produce a ton of steel in an electric arc furnace requires approximately
400 kilowatt-hours per short ton or about 440 kWh per metric tonne; the
theoretical minimum amount of energy required to melt a tonne of scrap steel is
300 kWh (melting point 1520°C/2768°F). Therefore, a 300-tonne, 300 MVA EAF
will require approximately 132 MWh of energy to melt the steel, and a "power-
on time" (the time that steel is being melted with an arc) of approximately 37
minutes. Electric arc steelmaking is only economical where there is plentiful
electricity, with a well-developed electrical grid. In many locations, mills operate
during off-peak hours when utilities have surplus power generating capacity and
the price of electricity is less.
Electrodes
There are 3 non consumable graphite electrodes used in one electric arc
furnace.
They are connected to 3 phase power supply (6.6 kV)
There should be a 6-7 inches gap between the electrodes and scrap to
ensure proper arcing.
If the gap between the electrodes and scrap is large, proper arcing will not
take place. And if the gap is very small, the air between the electrodes and
the scrap may get ionized and current will directly flow into the metal
without creating an arc.
Melting operation
The following operations take place during the smelting process.
The initial arcing of the furnace is started on low tap. This is carried out for
one minute.
The electrodes are adjusted, clamped and cleaned with a blast of
compressed air.
Over adjusting and under adjusting should be avoided to control the gap
between the electrodes and scrap.
VCB is closed and arced for 3-4 mins till the electrodes bore and go down.
Initial arcing is with longer arcs so that the outer scrap will melt fast. To
achieve this, the rheostat is adjusted in such a way that the load on
individual electrodes ranges from 19000 – 21000 A.
Lancing is done by inserting a long lancing pipe in the furnace through the
slag door. Oxygen is injected into the furnace for oxy-assisted melting.
When the scrap starts melting, carbon in the charge reacts with oxygen to
form CO and tries to escape from the furnace. If excess O2 is supplied CO
reacts with O2 to form CO2
4-5 degree angle is provided to the furnace for easy collapsing of scrap.
There should not be over tilting of furnace since this may cause electrode
breakage at the time of scrap collapse or may burn the side panels.
Sharp cracking sound indicated healthy melting of the metal.
First sample is taken at 1540-1560
o
C. By this time majority of the scrap
would’ve collapsed and side walls would have been exposed. To prevent
side wall refractory erosion shorter arc lengths are used. The furnace
current is increased by changing to lower taps and temperature of the
bath is raised.
All the slag metal jam should be cleared from the door before tilting the
Furnace for removal of slag. Only slag should be removed and not metal.
When metal comes out from the slag door, it will give continuous sparks.
While observing the slag flow through safety glasses, metal sparks cannot
be seen. Hence, slag metal flow should be observed once in between
without the safety goggles, so that metal flow through the door can be
identifies and stopped.
Temperature is checked. When the temperature is 1660-1670 C, the tap is
changed to 8 or 9.
without creating an arc.
Melting operation
The following operations take place during the smelting process.
The initial arcing of the furnace is started on low tap. This is carried out for
one minute.
The electrodes are adjusted, clamped and cleaned with a blast of
compressed air.
Over adjusting and under adjusting should be avoided to control the gap
between the electrodes and scrap.
VCB is closed and arced for 3-4 mins till the electrodes bore and go down.
Initial arcing is with longer arcs so that the outer scrap will melt fast. To
achieve this, the rheostat is adjusted in such a way that the load on
individual electrodes ranges from 19000 – 21000 A.
Lancing is done by inserting a long lancing pipe in the furnace through the
slag door. Oxygen is injected into the furnace for oxy-assisted melting.
When the scrap starts melting, carbon in the charge reacts with oxygen to
form CO and tries to escape from the furnace. If excess O2 is supplied CO
reacts with O2 to form CO2
4-5 degree angle is provided to the furnace for easy collapsing of scrap.
There should not be over tilting of furnace since this may cause electrode
breakage at the time of scrap collapse or may burn the side panels.
Sharp cracking sound indicated healthy melting of the metal.
First sample is taken at 1540-1560
o
C. By this time majority of the scrap
would’ve collapsed and side walls would have been exposed. To prevent
side wall refractory erosion shorter arc lengths are used. The furnace
current is increased by changing to lower taps and temperature of the
bath is raised.
All the slag metal jam should be cleared from the door before tilting the
Furnace for removal of slag. Only slag should be removed and not metal.
When metal comes out from the slag door, it will give continuous sparks.
While observing the slag flow through safety glasses, metal sparks cannot
be seen. Hence, slag metal flow should be observed once in between
without the safety goggles, so that metal flow through the door can be
identifies and stopped.
Temperature is checked. When the temperature is 1660-1670 C, the tap is
changed to 8 or 9.
Ladle is lifted from LPH (ladle pre heat station). Ladle lift should be so timed that
ladle with molten metal arrives JMP just before the previous heat pouring is
completed.
Ladle lip is prepared at slag off station (SOS).
Depending on the analysis of check sample Ferro-Silicon, Silicon -
Manganese and Graphite granules are added to ladle in metal stream.
Level the furnace, remove the roof mast lock pin, raise the electrode and
then raise the roof of the furnace.
Charge approximately 900 to 1200kgs of calcined lime and 200 to 250 kgs
of calcined petroleum coke / graphite powder.
Charge scraps wheels or metal cakes/skull or risers with the help of
magnet (2-2.5MT approximately)
The electrodes are lowered down. On supplying the necessary current and
voltage, an arc is produced between the electrode and the charge
material.
The gap between the electrode and charge is maintained by regulating the
movement of electrodes so that the arc remains between them and bums
continuously melting the charge material. The flux melts and forms a slag
that floats on the surface of the liquid metal. The slag prevents oxidation,
refines the metal and protects the furnace roof from excessive heat.
After the liquid metal has been achieved the desired temperature, the
electrodes are raised to extinguish the arc and the furnace is tilted
backwards to remove the slag. After 45-55minutes of arcing, start
emptying the scrap through slag door with oxygen lancing pipe. Spread
dolomite over the cleaned slag door. Clear slag door scrap. Remove full
slag before the temperature is 1630 degree Celsius. If the slag is sluggish,
shovel 25-30kgs of fluorspar on the slag.
Temperature must be controlled so that the maximum slag is removed by
1650 degree Celsius. Allow only a thin layer of slag on the metal surface.
Care must be taken not to remove the metal through slag door throughout
the slagging operation. Keep the slag doors clean by removing the slag
metal jam using pipe or a rod.
After almost all first slag is removed add Ferro-manganese at around 1650
degree Celsius and 150kgs of reducing slag mixture into the furnace to
make the slag reducing.
ladle with molten metal arrives JMP just before the previous heat pouring is
completed.
Ladle lip is prepared at slag off station (SOS).
Depending on the analysis of check sample Ferro-Silicon, Silicon -
Manganese and Graphite granules are added to ladle in metal stream.
Level the furnace, remove the roof mast lock pin, raise the electrode and
then raise the roof of the furnace.
Charge approximately 900 to 1200kgs of calcined lime and 200 to 250 kgs
of calcined petroleum coke / graphite powder.
Charge scraps wheels or metal cakes/skull or risers with the help of
magnet (2-2.5MT approximately)
The electrodes are lowered down. On supplying the necessary current and
voltage, an arc is produced between the electrode and the charge
material.
The gap between the electrode and charge is maintained by regulating the
movement of electrodes so that the arc remains between them and bums
continuously melting the charge material. The flux melts and forms a slag
that floats on the surface of the liquid metal. The slag prevents oxidation,
refines the metal and protects the furnace roof from excessive heat.
After the liquid metal has been achieved the desired temperature, the
electrodes are raised to extinguish the arc and the furnace is tilted
backwards to remove the slag. After 45-55minutes of arcing, start
emptying the scrap through slag door with oxygen lancing pipe. Spread
dolomite over the cleaned slag door. Clear slag door scrap. Remove full
slag before the temperature is 1630 degree Celsius. If the slag is sluggish,
shovel 25-30kgs of fluorspar on the slag.
Temperature must be controlled so that the maximum slag is removed by
1650 degree Celsius. Allow only a thin layer of slag on the metal surface.
Care must be taken not to remove the metal through slag door throughout
the slagging operation. Keep the slag doors clean by removing the slag
metal jam using pipe or a rod.
After almost all first slag is removed add Ferro-manganese at around 1650
degree Celsius and 150kgs of reducing slag mixture into the furnace to
make the slag reducing.
Mass Spectrometry
Mass Spectrometry is an analytic technique that utilizes the degree of deflection
of charged particles by a magnetic field to find the relative masses of molecular
ions and fragments.2 It is a powerful method because it provides a great deal of
information and can be conducted on tiny samples. Mass spectrometry has a
number of applications in organic chemistry, including:
Determining molecular mass
Finding out the structure of an unknown substance
Verifying the identity and purity of a known substance
Providing data on isotopic abundance
Step 1: The sample is vaporized, and then ionized by being bombarded by a
beam of highenergy electrons (usually at 70 eV). The electron beam knocks out
an electron from the molecule of the injected sample, creating a molecular ion
(which is also a radical cation because it has an unpaired electron and a positive
charge). Losing an electron weakens the bond, while the collision gives it extra
kinetic energy. These factors make it more likely for the molecular ion to break
into fragments as it travels through the mass spectrometer.
Step 2: There is a pair of oppositely charged plates in the ionization chamber.
The positively charged one causes the positively charged radical cation to
accelerate into an analyzer tube.
Step 3: The analyzer tube is surrounded by a curved magnetic field, which causes
the path of the radical cation to be deflected in proportion to its mass-to-charge
Mass Spectrometry is an analytic technique that utilizes the degree of deflection
of charged particles by a magnetic field to find the relative masses of molecular
ions and fragments.2 It is a powerful method because it provides a great deal of
information and can be conducted on tiny samples. Mass spectrometry has a
number of applications in organic chemistry, including:
Determining molecular mass
Finding out the structure of an unknown substance
Verifying the identity and purity of a known substance
Providing data on isotopic abundance
Step 1: The sample is vaporized, and then ionized by being bombarded by a
beam of highenergy electrons (usually at 70 eV). The electron beam knocks out
an electron from the molecule of the injected sample, creating a molecular ion
(which is also a radical cation because it has an unpaired electron and a positive
charge). Losing an electron weakens the bond, while the collision gives it extra
kinetic energy. These factors make it more likely for the molecular ion to break
into fragments as it travels through the mass spectrometer.
Step 2: There is a pair of oppositely charged plates in the ionization chamber.
The positively charged one causes the positively charged radical cation to
accelerate into an analyzer tube.
Step 3: The analyzer tube is surrounded by a curved magnetic field, which causes
the path of the radical cation to be deflected in proportion to its mass-to-charge
ratio (m/z). The flight path of the ion depends on its molecular mass, its charge,
and the strength of the magnetic field. Thus, at a given magnetic field strength,
ions of only one specific mass collide with the detector and are recorded.
Step 4: The strength of the magnetic field is varied in increments to produce a
mass spectrum, which is a plot of m/z (on the x axis) against relative abundance
(on the y axis). If we assume that all ions have a charge of +1, then the peaks give
the mass ratios and their heights give the proportions of ions of different masses.
General block diagram of Mass Spectrometer
Mass Spectroscopy is used in RWF to determine the composition of the elements
in the given sample of the metal. When the metal is melted in the furnace,
various additives such as Ferro Manganese, Graphite powder and silico
manganese are added to vary the composition of different elements such as C,
Mn and Si. Various samples are taken at each stage and hence sent to
Spectroscopy lab for elemental analysis.
1
st
sample – it is taken just after arcing and melting starts. Most of the impurities
are removed in the form of slag.
2
nd
sample – it is taken lancing process is over. After this Ferro Manganese and
limestone and calcined lime is added.
3
rd
sample – it is taken after all the additions are done. This is also called Pretap
Sample.
4
th
sample – it is also called Check sample. S and P should be in control. Excess
percentage of these elements results in cracks. Silicon (Si) is added to the laddle.
During this stage the temperature of the molten metal is around 1700 deg C.
Killing of steel is done to completely deoxidize by the addition of an agent before
casting, so that there is practically no evolution of gas during solidification. They
are characterized by a high degree of chemical homogeneity and freedom from
and the strength of the magnetic field. Thus, at a given magnetic field strength,
ions of only one specific mass collide with the detector and are recorded.
Step 4: The strength of the magnetic field is varied in increments to produce a
mass spectrum, which is a plot of m/z (on the x axis) against relative abundance
(on the y axis). If we assume that all ions have a charge of +1, then the peaks give
the mass ratios and their heights give the proportions of ions of different masses.
General block diagram of Mass Spectrometer
Mass Spectroscopy is used in RWF to determine the composition of the elements
in the given sample of the metal. When the metal is melted in the furnace,
various additives such as Ferro Manganese, Graphite powder and silico
manganese are added to vary the composition of different elements such as C,
Mn and Si. Various samples are taken at each stage and hence sent to
Spectroscopy lab for elemental analysis.
1
st
sample – it is taken just after arcing and melting starts. Most of the impurities
are removed in the form of slag.
2
nd
sample – it is taken lancing process is over. After this Ferro Manganese and
limestone and calcined lime is added.
3
rd
sample – it is taken after all the additions are done. This is also called Pretap
Sample.
4
th
sample – it is also called Check sample. S and P should be in control. Excess
percentage of these elements results in cracks. Silicon (Si) is added to the laddle.
During this stage the temperature of the molten metal is around 1700 deg C.
Killing of steel is done to completely deoxidize by the addition of an agent before
casting, so that there is practically no evolution of gas during solidification. They
are characterized by a high degree of chemical homogeneity and freedom from
gas porosity. For this purpose, Aluminium Stars (Al) are added to ensure all the
gasses escapes out.
5
th
sample – It is called the final sample. This is taken just before the casting
process.
RWF manufactures wheels for coach and wagon.
Wagon wheels – they are meant for goods train and hence carry large amount of
loads. Here speed is limited and hence high strength is required. To achieve this
Carbon percentage is slightly increased which imparts high hardness.
Coach wheels – they are meant to carry passengers and hence here speed is
criteria. Trains like Rajdhani and Duronto, travel at high speeds and carry
passengers so total load is acting on the wheel is comparatively low but flexibility
is the criteria here. To achieve this low carbon content is maintained which
imparts high fatigue strength and better flexibility.
The following table shows the chemical composition of 2 wheels
% Composition of Metals Coach wheels Wagon wheels
Carbon 0.47 – 0.57 0.57 – 0.67
Manganese 0.6 – 0.8 0.6 – 0.8
Silicon 0.7 0.7
Phosphorus 0.03 0.03
Sulphur 0.03 0.03
Chromium 0.15 0.15
Nickel 0.25 0.25
Vanadium Not Specified Not Specified
Molybdenum 0.06 0.06
Cr + Ni + Mo 0.06 0.06
P + S - -
Copper 0.25 0.25
Aluminum Not Specified Not Specified
Titanium Not Specified Not Specified
Niobium Not Specified Not Specified
Hydrogen 3 ppm 3 ppm
Nitrogen 0.007 0.007
Brinell Hardness Number BHN 255 – 321 255 – 321
gasses escapes out.
5
th
sample – It is called the final sample. This is taken just before the casting
process.
RWF manufactures wheels for coach and wagon.
Wagon wheels – they are meant for goods train and hence carry large amount of
loads. Here speed is limited and hence high strength is required. To achieve this
Carbon percentage is slightly increased which imparts high hardness.
Coach wheels – they are meant to carry passengers and hence here speed is
criteria. Trains like Rajdhani and Duronto, travel at high speeds and carry
passengers so total load is acting on the wheel is comparatively low but flexibility
is the criteria here. To achieve this low carbon content is maintained which
imparts high fatigue strength and better flexibility.
The following table shows the chemical composition of 2 wheels
% Composition of Metals Coach wheels Wagon wheels
Carbon 0.47 – 0.57 0.57 – 0.67
Manganese 0.6 – 0.8 0.6 – 0.8
Silicon 0.7 0.7
Phosphorus 0.03 0.03
Sulphur 0.03 0.03
Chromium 0.15 0.15
Nickel 0.25 0.25
Vanadium Not Specified Not Specified
Molybdenum 0.06 0.06
Cr + Ni + Mo 0.06 0.06
P + S - -
Copper 0.25 0.25
Aluminum Not Specified Not Specified
Titanium Not Specified Not Specified
Niobium Not Specified Not Specified
Hydrogen 3 ppm 3 ppm
Nitrogen 0.007 0.007
Brinell Hardness Number BHN 255 – 321 255 – 321
Procedure
The samples are brought from the furnace and are first polished to achieve a
good and smooth surface finish. The samples from every heat is brought and
analyzed in the ARL Metal analyzer.
The ARL 3460 Metals Analyzer is an optical emission spectrometer offering fast,
accurate metals analysis for a variety of applications in laboratories or on the
production floors of various companies analyzing, handling, processing or
producing metals and metallic products, including foundries, metal processors,
metals producers, contract, development or institutional laboratories and
enterprises involved in the recycling of metals. Configured and calibrated in the
factory to meet customer specific requirements, the ARL 3460 Metals Analyzer is
routinely deployed in analyzing nitrogen and oxygen in steels or oxygen in
copper.
Stability, accuracy, precision and low detection limits.
Robustness and reliability.
Continuous enhancement programs allow new features to be incorporated into
the system as they became available.
Easy integration to increase productivity.
Flexible and powerful Thermo Scientific™ OXSAS™ Analytical Software.
Key to Metals database.
Low operating cost, offers cost reduction compared to other techniques.
Simple one-click routine analysis launch and full traceability.
Features access to recent analyses for on-screen comparison. Simple graphic
user interface and a triple navigation style including grids and tree views.
The machine heats the surface of the metal using electrodes. There is argon
atmosphere created in the region to prevent oxidation. It is heated to plasma
stage and hence the atoms of each element are excited to higher state. When
they return to the lower ground state, they tend to release energy. This energy
has a particular intensity and wavelength.
Intensity of this radiation determines % composition.
Wavelength determines the type of element.
The samples are brought from the furnace and are first polished to achieve a
good and smooth surface finish. The samples from every heat is brought and
analyzed in the ARL Metal analyzer.
The ARL 3460 Metals Analyzer is an optical emission spectrometer offering fast,
accurate metals analysis for a variety of applications in laboratories or on the
production floors of various companies analyzing, handling, processing or
producing metals and metallic products, including foundries, metal processors,
metals producers, contract, development or institutional laboratories and
enterprises involved in the recycling of metals. Configured and calibrated in the
factory to meet customer specific requirements, the ARL 3460 Metals Analyzer is
routinely deployed in analyzing nitrogen and oxygen in steels or oxygen in
copper.
Stability, accuracy, precision and low detection limits.
Robustness and reliability.
Continuous enhancement programs allow new features to be incorporated into
the system as they became available.
Easy integration to increase productivity.
Flexible and powerful Thermo Scientific™ OXSAS™ Analytical Software.
Key to Metals database.
Low operating cost, offers cost reduction compared to other techniques.
Simple one-click routine analysis launch and full traceability.
Features access to recent analyses for on-screen comparison. Simple graphic
user interface and a triple navigation style including grids and tree views.
The machine heats the surface of the metal using electrodes. There is argon
atmosphere created in the region to prevent oxidation. It is heated to plasma
stage and hence the atoms of each element are excited to higher state. When
they return to the lower ground state, they tend to release energy. This energy
has a particular intensity and wavelength.
Intensity of this radiation determines % composition.
Wavelength determines the type of element.
The percentage of Hydrogen is determined by RH-402 hydrogen determinator.
This machine determines the percentage of hydrogen in the given sample.
This machine determines the percentage of hydrogen in the given sample.
Steel Pouring Shop
Tapping of molten metal
• The temperature is checked twice before tapping the heat.
• In the normal conditions, without ladle delay, 1690-1695 C temperature is
considered for tapping (when the ladle preparation is over in ten minutes time
and final analysis is received within ten minutes)
• O2 is used to open the tap hole from the tap hole inside. If the tap hole does
not open in time, oxygen pipe is used for tap hole opening from the slag door
side.
• While tapping, care is required to see that only metal comes out of the tap
hole initially and not with the slag. This can be done by tilting the furnace till the
metal level is above the tap hole.
Once the slag is taken out and the chemical composition of the molten metal is
tested and is same as required lift the ladle from John Mohr Pit (JMP) with the
help of crane and pours the molten metal to the ladle from the furnace.
Insulation powder is thrown into ladles to prevent radiation loss of liquid
metal.
Excess molten metal which cannot be poured into the ladle may be
emptied into pigging pot or dirt floor.
In case of viscous slag, one operator must push the slag with the steel
rabble and the second operator must take the sample
Ladle Preheating
Ladle pre-heaters are provided with micro-control values and feedback system
for proper temperature control. The temperature is to be set manually, fuel flow
control is automatic. Total preheating cycle is 21 hrs. An improperly heated ladle
will show tendencies of spilling. The spilling can also be due to inadequate
elimination of moisture. Hence, preheating cycle prescribed is followed
meticulously. Ladle is kept on preheated with proper planning so that the ladle is
ready by the time the working ladle becomes condemnable. After completion of
above cycle, if ladle is not taken for use, the temperature is brought down to
1000 C till 2 hours before usage. Before using the ladle the temperature is raised
to 1200 C.
Procedure
• After pouring is over, ladle is covered with dummy cover and kept at JMP
home position till it is removed from the tank to avoid thermal shock to the
Tapping of molten metal
• The temperature is checked twice before tapping the heat.
• In the normal conditions, without ladle delay, 1690-1695 C temperature is
considered for tapping (when the ladle preparation is over in ten minutes time
and final analysis is received within ten minutes)
• O2 is used to open the tap hole from the tap hole inside. If the tap hole does
not open in time, oxygen pipe is used for tap hole opening from the slag door
side.
• While tapping, care is required to see that only metal comes out of the tap
hole initially and not with the slag. This can be done by tilting the furnace till the
metal level is above the tap hole.
Once the slag is taken out and the chemical composition of the molten metal is
tested and is same as required lift the ladle from John Mohr Pit (JMP) with the
help of crane and pours the molten metal to the ladle from the furnace.
Insulation powder is thrown into ladles to prevent radiation loss of liquid
metal.
Excess molten metal which cannot be poured into the ladle may be
emptied into pigging pot or dirt floor.
In case of viscous slag, one operator must push the slag with the steel
rabble and the second operator must take the sample
Ladle Preheating
Ladle pre-heaters are provided with micro-control values and feedback system
for proper temperature control. The temperature is to be set manually, fuel flow
control is automatic. Total preheating cycle is 21 hrs. An improperly heated ladle
will show tendencies of spilling. The spilling can also be due to inadequate
elimination of moisture. Hence, preheating cycle prescribed is followed
meticulously. Ladle is kept on preheated with proper planning so that the ladle is
ready by the time the working ladle becomes condemnable. After completion of
above cycle, if ladle is not taken for use, the temperature is brought down to
1000 C till 2 hours before usage. Before using the ladle the temperature is raised
to 1200 C.
Procedure
• After pouring is over, ladle is covered with dummy cover and kept at JMP
home position till it is removed from the tank to avoid thermal shock to the
brick and a heavy radiation loss and solidification of liquid metal.
• The ladle is lifted from the pit, 12 to 14 minutes before the heat is ready. Ladle
lifting time should be so synchronized that ladle with full metal comes to JMP as
soon as previous heat is just poured. Hence ideally ladle may be lifted when 17-
18 wheels is cast from the previous heat.
• The number of wheels poured is checked to assess the quantity of liquid metal
available in the ladle to be used for tapping.
• The ladle sidewall should be inspected thoroughly after lowering the ladle at
the SOS. In case of every wide opening in the brick joints at the lower side wall
ladle should be condemned.
• Ladle should be centred properly at the tapping station so that the metal
stream strikes the centre of the ladle. Metal stream directed onto sides’ wall
may cause sidewall erosion and sidewall punctures.
• After slag off, the lip portion is covered with ramming mass and then with the
raw dolomite, the slag metal jam below the lip and below the stiffener ring
should be cleaned before the ladle is sent to moulding room.
MOULDING SHOP
In this part of the wheel shop the molten metal is poured into the mould box
consisting of the cope and drag assembly, later the caste wheel is separated
from cope and drag assembly and is made to undergo certain heat treatment
process.
Cast Wheel Processing
CASTING
The casting process begins with pouring of molten metal into cope-drag
assembly, a small period of air cooling and finally separating the cope and drag
assembly to obtain the casted wheel
1. Laddle placement
Ladle is placed in the John Mohr Tank by SMS. It is targeted to time the
tapping so that ladle can be placed in John Mohr Tank at home position. If
pouring pit is already free by the time ladle comes, ladle is placed in John
Mohr Tank in pouring position.
2. Measurement of Temperature at John Mohr Tank
The casting process followed in RWF is critically dependent on time and
temperature. The casting should be complete within a narrow band of
metal temperature in shortest time possible. The metal temperature is
last taken in John Mohr Tank with disposable Thermo Couple tips.
- An ideal temperature band in JMP is 1600 C
• The ladle is lifted from the pit, 12 to 14 minutes before the heat is ready. Ladle
lifting time should be so synchronized that ladle with full metal comes to JMP as
soon as previous heat is just poured. Hence ideally ladle may be lifted when 17-
18 wheels is cast from the previous heat.
• The number of wheels poured is checked to assess the quantity of liquid metal
available in the ladle to be used for tapping.
• The ladle sidewall should be inspected thoroughly after lowering the ladle at
the SOS. In case of every wide opening in the brick joints at the lower side wall
ladle should be condemned.
• Ladle should be centred properly at the tapping station so that the metal
stream strikes the centre of the ladle. Metal stream directed onto sides’ wall
may cause sidewall erosion and sidewall punctures.
• After slag off, the lip portion is covered with ramming mass and then with the
raw dolomite, the slag metal jam below the lip and below the stiffener ring
should be cleaned before the ladle is sent to moulding room.
MOULDING SHOP
In this part of the wheel shop the molten metal is poured into the mould box
consisting of the cope and drag assembly, later the caste wheel is separated
from cope and drag assembly and is made to undergo certain heat treatment
process.
Cast Wheel Processing
CASTING
The casting process begins with pouring of molten metal into cope-drag
assembly, a small period of air cooling and finally separating the cope and drag
assembly to obtain the casted wheel
1. Laddle placement
Ladle is placed in the John Mohr Tank by SMS. It is targeted to time the
tapping so that ladle can be placed in John Mohr Tank at home position. If
pouring pit is already free by the time ladle comes, ladle is placed in John
Mohr Tank in pouring position.
2. Measurement of Temperature at John Mohr Tank
The casting process followed in RWF is critically dependent on time and
temperature. The casting should be complete within a narrow band of
metal temperature in shortest time possible. The metal temperature is
last taken in John Mohr Tank with disposable Thermo Couple tips.
- An ideal temperature band in JMP is 1600 C
- Aluminium stars are plunged at temperature ≤ 1610 C
- If measured temperature is above 1610 C, metal is allowed to cool down
till temperature come below 1610 C. To facilitate cooling, the slag layer is
broken and dispersed towards ladle wall.
- The lancer is calibrated to give correct result.
- Slag is displaced with a rabble before dipping the TC tips
1) Two samples are taken, one for Hydrogen and another for final chemical
analysis.
2) Immediately after Aluminium starts are plunged, the JMP is covered.
- The tube is fully dipped in the metal and taken up by approx. half its length.
- 15 to 20 kg of dry sand is sprayed on the metal towards ladle side wall
through pneumatic sand dispenser.
- Sand is added to neutralize basic slag which has property to attach Alumina
present in ladle brick. Addition of sand reduces side wall erosion.
- If incoming metal temperature is <1600 C, 100kg Ladle Insulating Material
is added instead of 50 kg as mentioned above.
- While adding sand and Ladle Insulating Material, the tube is continuously
and gently raised and lowered. This is to avoid metal chilling within tube and
also to acclimatise the tube to high temperature metal.
3) Now the cover is lowered and clamped, hoist released and pouring crane comes
to the pouring station.
4) Pouring crane has two main functions, mould movements and metal
pouring. The Northern operator puts a hot asbestos gasket on the pouring
point.
- The asbestos gaskets should be moisture free. The holed edges of the gasket
should be smoothly cut and without any loose ends or burrs. The gasket should
have uniform thickness.
- Double gasket is used on isolated occasions when metal penetration under
gasket is observed due to tube sink age or to avoid run out in case of any
mould centring problem. For such occasions, pre-heated asbestos gaskets are
kept near pouring station.
5) Mould is gently kept on the pouring point. Following activities take place:
- High Pressure clamps (2 nos.) hold the moulds and pouring starts.
- Southern operator puts the sensor rod on stopper pipe.
6) As soon as the metal touches stopper head, pouring rate changes to control
rate.
- The southern operator takes out the sensor rod. - When metal touches probe,
immediately the centre plunger comes down closing the in gate opening.
- Exhaust opens and pouring is completed.
- Low pressure clamps come down, High pressure clamps go up.
- B frame lifts the mould and carries it to PC
- If measured temperature is above 1610 C, metal is allowed to cool down
till temperature come below 1610 C. To facilitate cooling, the slag layer is
broken and dispersed towards ladle wall.
- The lancer is calibrated to give correct result.
- Slag is displaced with a rabble before dipping the TC tips
1) Two samples are taken, one for Hydrogen and another for final chemical
analysis.
2) Immediately after Aluminium starts are plunged, the JMP is covered.
- The tube is fully dipped in the metal and taken up by approx. half its length.
- 15 to 20 kg of dry sand is sprayed on the metal towards ladle side wall
through pneumatic sand dispenser.
- Sand is added to neutralize basic slag which has property to attach Alumina
present in ladle brick. Addition of sand reduces side wall erosion.
- If incoming metal temperature is <1600 C, 100kg Ladle Insulating Material
is added instead of 50 kg as mentioned above.
- While adding sand and Ladle Insulating Material, the tube is continuously
and gently raised and lowered. This is to avoid metal chilling within tube and
also to acclimatise the tube to high temperature metal.
3) Now the cover is lowered and clamped, hoist released and pouring crane comes
to the pouring station.
4) Pouring crane has two main functions, mould movements and metal
pouring. The Northern operator puts a hot asbestos gasket on the pouring
point.
- The asbestos gaskets should be moisture free. The holed edges of the gasket
should be smoothly cut and without any loose ends or burrs. The gasket should
have uniform thickness.
- Double gasket is used on isolated occasions when metal penetration under
gasket is observed due to tube sink age or to avoid run out in case of any
mould centring problem. For such occasions, pre-heated asbestos gaskets are
kept near pouring station.
5) Mould is gently kept on the pouring point. Following activities take place:
- High Pressure clamps (2 nos.) hold the moulds and pouring starts.
- Southern operator puts the sensor rod on stopper pipe.
6) As soon as the metal touches stopper head, pouring rate changes to control
rate.
- The southern operator takes out the sensor rod. - When metal touches probe,
immediately the centre plunger comes down closing the in gate opening.
- Exhaust opens and pouring is completed.
- Low pressure clamps come down, High pressure clamps go up.
- B frame lifts the mould and carries it to PC
-3A. Simultaneously, a frame picks up and brings it to the pouring point.
Different steps in Pouring and Moulding:
Once the drag comes to respective close down position, the operator does the
following:
Cleans the drag with blowing air at 25-30 psi pressure.
Inspects the drag for any apex damage, oil drop on drag surface,
excessive damage of ignite sleeve, availability/condition of four no.
springs on drag retaining ring. If necessary he decides to bypass the
drag.
The cope is picked up with close down crane, cleaned with
compressed air and very delicately kept on the drag fully.
To ensure sound casting, at least 50 mm metal is left within tube. Hence
towards the completion of pouring, a dip rod is inserted to estimate the metal
left. Keeping in mind the thumb rule of 1 wheel = 50 mm of metal, the pouring
supervisor decides no. of balance.
Once pouring is complete, the tube opening is immediately covered with a 20
mm thick circular plate cover kept on two asbestos gaskets. This is to block any
air entry inside tube which may oxidize metal deposition available in the tube.
JMP cover along with tube is taken out and kept in holding furnace.
Aluminium Plunging in Ladle:
Aluminium plunging is done in the ladle when the metal temperature is less than
1610 C. This is primarily to take care of the residual gases in the liquid metal. To
achieve this, aluminium stars are added
Mould splitting:
Initially the splitting time is set based on the average of the previous heat.
Vacant hot wheel kiln is selected.
When the set splitting time is completed for a particular mould, the
indicator light glows.
Then the splitter crane is lowered, cope clamped and lifted gently. In case
the wheel is sticking to the cope, splitter crane is moved up and down over
the drag gently a number of times.
If the wheel is released, the cope is released to the cope line. If risers do
not come out with cope during splitting i.e., remain with wheel, they are
broken with scissors or otherwise broken with rods manually.
If sticking risers could not be broken, the wheel is removed out of line and
transferred to the area specified. If the wheel is sticking to the drags due
Different steps in Pouring and Moulding:
Once the drag comes to respective close down position, the operator does the
following:
Cleans the drag with blowing air at 25-30 psi pressure.
Inspects the drag for any apex damage, oil drop on drag surface,
excessive damage of ignite sleeve, availability/condition of four no.
springs on drag retaining ring. If necessary he decides to bypass the
drag.
The cope is picked up with close down crane, cleaned with
compressed air and very delicately kept on the drag fully.
To ensure sound casting, at least 50 mm metal is left within tube. Hence
towards the completion of pouring, a dip rod is inserted to estimate the metal
left. Keeping in mind the thumb rule of 1 wheel = 50 mm of metal, the pouring
supervisor decides no. of balance.
Once pouring is complete, the tube opening is immediately covered with a 20
mm thick circular plate cover kept on two asbestos gaskets. This is to block any
air entry inside tube which may oxidize metal deposition available in the tube.
JMP cover along with tube is taken out and kept in holding furnace.
Aluminium Plunging in Ladle:
Aluminium plunging is done in the ladle when the metal temperature is less than
1610 C. This is primarily to take care of the residual gases in the liquid metal. To
achieve this, aluminium stars are added
Mould splitting:
Initially the splitting time is set based on the average of the previous heat.
Vacant hot wheel kiln is selected.
When the set splitting time is completed for a particular mould, the
indicator light glows.
Then the splitter crane is lowered, cope clamped and lifted gently. In case
the wheel is sticking to the cope, splitter crane is moved up and down over
the drag gently a number of times.
If the wheel is released, the cope is released to the cope line. If risers do
not come out with cope during splitting i.e., remain with wheel, they are
broken with scissors or otherwise broken with rods manually.
If sticking risers could not be broken, the wheel is removed out of line and
transferred to the area specified. If the wheel is sticking to the drags due
to run back metal or overflow, it is by-passed and removed from the line
along with the wheel.
The splitting time is fine-tuned so that there is no dripping and
simultaneously the risers come out with copes.
Wheels short poured, run back, with fin, with pokers, heavy laps and with
slag/refractory inclusion etc., are removed.
Hot Wheel Kiln
There are three hot wheel kilns each having a capacity to hold 33 wheels hot
wheel kilns ensures controlled cooling of the wheels. The wheel temperature
after splitting is between 900 to C and after hot wheels kilns should be
between 450 to 575 C. The approximate traverse time through the kiln is 50 mins.
Sprue Wash:
After the controlled air cooling the wheel coming out of the kiln is at a
temperature of about 400-600 degree Celsius. It contains a little part of the
runner and riser which is not removed during splitting. The part must be
removed before the further cleaning of the wheel.
- There are three sprue wash stations and one chipping station.
- The ideal temperature at sprue wash is 425 C to 550 C. The hot wheel
kiln damper opening/closing should be adjusted accordingly.
- 25 mm dia copper coated graphite electrode is used for Sprue wash. The
electrode is required to be held correctly into the jaws of the holder. A
gap of 6” to 8” should be maintained between the holder jaws and arcing
point.
- Cracks can appear in sprue area of wheel if wheel is too hot or too cold.
Optimum temperature before sprue wash is 425C to 550C.
- If, wheel temperature is less than 380 C at sprue wash because of delay,
the wheel is off loaded. After hub cutting the wheel is sprue ground.
At the last sprue wash station, after the sprue wash is over, the stopper pipe
is cut and the wheel is discharged.
The station has a pneumatically activated arm having serration cut in and also
having a wire brush to dislodged and clean the deposited metal. After the
chipping operator completes the last wheel of any heat and that wheel is hub
stamped, he switches off the power to hub stamping. The hub cutting operator now
changes the heat no. in the hub stamping machine.
- Eventually Sprue wash stations will be replaced with sprue grinding
machines because of a no. of advantages like:
along with the wheel.
The splitting time is fine-tuned so that there is no dripping and
simultaneously the risers come out with copes.
Wheels short poured, run back, with fin, with pokers, heavy laps and with
slag/refractory inclusion etc., are removed.
Hot Wheel Kiln
There are three hot wheel kilns each having a capacity to hold 33 wheels hot
wheel kilns ensures controlled cooling of the wheels. The wheel temperature
after splitting is between 900 to C and after hot wheels kilns should be
between 450 to 575 C. The approximate traverse time through the kiln is 50 mins.
Sprue Wash:
After the controlled air cooling the wheel coming out of the kiln is at a
temperature of about 400-600 degree Celsius. It contains a little part of the
runner and riser which is not removed during splitting. The part must be
removed before the further cleaning of the wheel.
- There are three sprue wash stations and one chipping station.
- The ideal temperature at sprue wash is 425 C to 550 C. The hot wheel
kiln damper opening/closing should be adjusted accordingly.
- 25 mm dia copper coated graphite electrode is used for Sprue wash. The
electrode is required to be held correctly into the jaws of the holder. A
gap of 6” to 8” should be maintained between the holder jaws and arcing
point.
- Cracks can appear in sprue area of wheel if wheel is too hot or too cold.
Optimum temperature before sprue wash is 425C to 550C.
- If, wheel temperature is less than 380 C at sprue wash because of delay,
the wheel is off loaded. After hub cutting the wheel is sprue ground.
At the last sprue wash station, after the sprue wash is over, the stopper pipe
is cut and the wheel is discharged.
The station has a pneumatically activated arm having serration cut in and also
having a wire brush to dislodged and clean the deposited metal. After the
chipping operator completes the last wheel of any heat and that wheel is hub
stamped, he switches off the power to hub stamping. The hub cutting operator now
changes the heat no. in the hub stamping machine.
- Eventually Sprue wash stations will be replaced with sprue grinding
machines because of a no. of advantages like:
Better surface finish
Less environmental hardness.
More automation.
Less wheel defect and fewer wheels off load for machining.
Hub Stamping
After chipping the wheel is made horizontal with drag side up and released on the
conveyer. In the hub stamping, heat no. is hot punched on the back hub. Depth of
punching is normally 1.5 mm.
Hub Cutting
The center portion of the wheel, where the axle fits in, need to be bored in order
to remove the casted portion from the wheel. This is done by up cutting process.
The hole is initially bored for a diameter lesser than required during this
process using Hub Cutting Machine. Hence the process is also called Hub cutting
process.
- Hub cutting is done in four nos. hub cutters available. Hub cutters 1 & 2 are
mechanical type. The diameter of bore is adjusted through the cam provided.
- Hub cutter 3 & 4 are CNC type.
- Wheel temperature before hub cutting should be above 265 C. If due to any
reason wheel becomes cold, the wheel is offloaded without hub cutting.
- Before hub cutting, the pilot hole is thoroughly cleaned up to the end of dome
on cope side.
- The top face of back hub is cleaned with a wire brush to take out spray material
and blown with compressed air.
- Wheel is centred properly with the centring device of the machine before
starting hub cutting.
- The torch flame is adjusted to have a blue flame.
- After the pilot hole is heated, cutting operation is started by opening the high
pressure oxygen.
- This hole is initially cleaned using pneumatic air, so that the hub cutting
process can be begun from this portion.
- The oxy-acetylene gas flame is first directed to the pilot hole and then moved
along the radius and finally moved in a circular shape.
- Hence the circular hub which is being cut falls after the arc completes a circle of
required radius.
The nozzle of the machine need to be regularly changed to prevent hub not falling
situation i.e., if insufficient flame is supplied for cutting due to defects in the
nozzle, the hub is not completely cut through the whole depth of the wheel.
Less environmental hardness.
More automation.
Less wheel defect and fewer wheels off load for machining.
Hub Stamping
After chipping the wheel is made horizontal with drag side up and released on the
conveyer. In the hub stamping, heat no. is hot punched on the back hub. Depth of
punching is normally 1.5 mm.
Hub Cutting
The center portion of the wheel, where the axle fits in, need to be bored in order
to remove the casted portion from the wheel. This is done by up cutting process.
The hole is initially bored for a diameter lesser than required during this
process using Hub Cutting Machine. Hence the process is also called Hub cutting
process.
- Hub cutting is done in four nos. hub cutters available. Hub cutters 1 & 2 are
mechanical type. The diameter of bore is adjusted through the cam provided.
- Hub cutter 3 & 4 are CNC type.
- Wheel temperature before hub cutting should be above 265 C. If due to any
reason wheel becomes cold, the wheel is offloaded without hub cutting.
- Before hub cutting, the pilot hole is thoroughly cleaned up to the end of dome
on cope side.
- The top face of back hub is cleaned with a wire brush to take out spray material
and blown with compressed air.
- Wheel is centred properly with the centring device of the machine before
starting hub cutting.
- The torch flame is adjusted to have a blue flame.
- After the pilot hole is heated, cutting operation is started by opening the high
pressure oxygen.
- This hole is initially cleaned using pneumatic air, so that the hub cutting
process can be begun from this portion.
- The oxy-acetylene gas flame is first directed to the pilot hole and then moved
along the radius and finally moved in a circular shape.
- Hence the circular hub which is being cut falls after the arc completes a circle of
required radius.
The nozzle of the machine need to be regularly changed to prevent hub not falling
situation i.e., if insufficient flame is supplied for cutting due to defects in the
nozzle, the hub is not completely cut through the whole depth of the wheel.
Hence, the cut portion will not fall after complete circular path of the flame. The
distance of 8-12mm must be maintained between the nozzle tip and the back hub
face for proper cutting action.
- The machines are provided with automatic cut off of cutting oxygen
pressure as soon as cutting is over. Automatic cut off is very important to avoid
any gouging of the bore.
- If any hub does not fall, sledge hammer is used to dislodge it. Some of wheels
whose hub does not fall off are off loaded. In such cases nozzle performance,
gas pressures, cutting oxygen pressure, cutting speed and quality of flame are
checked.
Heat treatment of wheels
It is done:
- To eliminate residual stresses that is present in the axle during forging and
subsequent cooling.
- To homogenize the structure of the metal of forging.
- To impart, to the axle that degree of hardness, this makes it most easy to
machine.
- To improve strength, toughness and other mechanical properties of the axle.
Metallic materials consist of a microstructure of small crystals called "grains"
or crystallites. The nature of the grains (i.e. Grain size and composition) is one
of the most effective factors that can determine the overall mechanical behavior
of the metal.
Heat treatment provides an efficient way to manipulate the properties of the
metal by controlling the rate of diffusion and the rate of cooling within the
microstructure. Heat treating is often used to alter the mechanical properties
of an alloy, manipulating properties such as the hardness, strength, toughness,
ductility, and elasticity.
The solidification of wheel in mould blank is a non-uniform process in terms of
chemical composition and rate of solidification.
Normalising:
The first process in heat treatment is normalising. In normalising the wheel is
heated beyond upper critical temperature and soaked at that temperature.
Normalizing is a technique used to provide uniformity in grain size and
composition throughout an alloy. The term is often used for ferrous alloys that
have been austenitized and then cooled in open air. Normalizing not only
produces pearlite, but also bainite sometimes martensite, which gives harder
and strongersteel, but with less dificuty for the same composition than full
distance of 8-12mm must be maintained between the nozzle tip and the back hub
face for proper cutting action.
- The machines are provided with automatic cut off of cutting oxygen
pressure as soon as cutting is over. Automatic cut off is very important to avoid
any gouging of the bore.
- If any hub does not fall, sledge hammer is used to dislodge it. Some of wheels
whose hub does not fall off are off loaded. In such cases nozzle performance,
gas pressures, cutting oxygen pressure, cutting speed and quality of flame are
checked.
Heat treatment of wheels
It is done:
- To eliminate residual stresses that is present in the axle during forging and
subsequent cooling.
- To homogenize the structure of the metal of forging.
- To impart, to the axle that degree of hardness, this makes it most easy to
machine.
- To improve strength, toughness and other mechanical properties of the axle.
Metallic materials consist of a microstructure of small crystals called "grains"
or crystallites. The nature of the grains (i.e. Grain size and composition) is one
of the most effective factors that can determine the overall mechanical behavior
of the metal.
Heat treatment provides an efficient way to manipulate the properties of the
metal by controlling the rate of diffusion and the rate of cooling within the
microstructure. Heat treating is often used to alter the mechanical properties
of an alloy, manipulating properties such as the hardness, strength, toughness,
ductility, and elasticity.
The solidification of wheel in mould blank is a non-uniform process in terms of
chemical composition and rate of solidification.
Normalising:
The first process in heat treatment is normalising. In normalising the wheel is
heated beyond upper critical temperature and soaked at that temperature.
Normalizing is a technique used to provide uniformity in grain size and
composition throughout an alloy. The term is often used for ferrous alloys that
have been austenitized and then cooled in open air. Normalizing not only
produces pearlite, but also bainite sometimes martensite, which gives harder
and strongersteel, but with less dificuty for the same composition than full
annealing.
Normalising is done in a rotary hearth diesel fired furnace. The furnace has two
rows of 48 pedestals each and can hold 90 wheels at a time.
There are seven zones in the furnace. The location wise zone and set
temperature are set accordingly
The wheels are loaded on each pedestal through the charging machine
either in auto mode or in manual mode. Wheels should be placed on the
pedestals properly.
Following time limit is followed:
• Any wheel should be soaked at requisite temperature.
• Total hold up of the wheel in the soaking should not be more than 105
minutes including the time of break down. If hold up time is more than 105
minutes, the wheel is off loaded.
• In case of problem in quencher, discharging machine or draw furnace the
wheels can be held upto one hour in Normalizing Furnace in addition to its
normal time of 90 minutes. In case the delay is more than one hour, the wheels
should be removed from the furnace and should be stacked separately for re-
heat treatment with marking of RHT and heat number.
Rim Quenching
Quenching is a process of cooling a metal at a rapid rate. This is most often
done to produce a martensite transformation. In ferrous alloys, this will often
produce a harder metal, while non-ferrous alloys will usually become softer
than normal.
To harden by quenching, a metal (usually steel or cast iron) must be heated
above the upper critical temperature and then quickly cooled. Depending on
the alloy and other considerations (such as concern for maximum hardness vs.
cracking and distortion), cooling may be done with forced air or other gases,
(such as nitrogen).
- During this process hot wheel discharged from NF is held drag side up in the
quenching station and high pressure water is impinged on the wheel rim.
- On exposure to cold water i.e., getting quenched the rim suddenly cools, but
the plate remains hot.
- Subsequently, the plate and hub are subjected to slow cooling and on
shrinking during cooling, the plate and hub squeeze the already cold rim
towards the centre; thereby residual compressive stress is imparted on wheel
rim.
- The bulk stress condition is assessed through saw cutting test as a destructive
test in Met. Lab.
- There are six rim quenchers. Any rim quenchers is selected automatically
Normalising is done in a rotary hearth diesel fired furnace. The furnace has two
rows of 48 pedestals each and can hold 90 wheels at a time.
There are seven zones in the furnace. The location wise zone and set
temperature are set accordingly
The wheels are loaded on each pedestal through the charging machine
either in auto mode or in manual mode. Wheels should be placed on the
pedestals properly.
Following time limit is followed:
• Any wheel should be soaked at requisite temperature.
• Total hold up of the wheel in the soaking should not be more than 105
minutes including the time of break down. If hold up time is more than 105
minutes, the wheel is off loaded.
• In case of problem in quencher, discharging machine or draw furnace the
wheels can be held upto one hour in Normalizing Furnace in addition to its
normal time of 90 minutes. In case the delay is more than one hour, the wheels
should be removed from the furnace and should be stacked separately for re-
heat treatment with marking of RHT and heat number.
Rim Quenching
Quenching is a process of cooling a metal at a rapid rate. This is most often
done to produce a martensite transformation. In ferrous alloys, this will often
produce a harder metal, while non-ferrous alloys will usually become softer
than normal.
To harden by quenching, a metal (usually steel or cast iron) must be heated
above the upper critical temperature and then quickly cooled. Depending on
the alloy and other considerations (such as concern for maximum hardness vs.
cracking and distortion), cooling may be done with forced air or other gases,
(such as nitrogen).
- During this process hot wheel discharged from NF is held drag side up in the
quenching station and high pressure water is impinged on the wheel rim.
- On exposure to cold water i.e., getting quenched the rim suddenly cools, but
the plate remains hot.
- Subsequently, the plate and hub are subjected to slow cooling and on
shrinking during cooling, the plate and hub squeeze the already cold rim
towards the centre; thereby residual compressive stress is imparted on wheel
rim.
- The bulk stress condition is assessed through saw cutting test as a destructive
test in Met. Lab.
- There are six rim quenchers. Any rim quenchers is selected automatically
depending on its availability.
Each rim quencher has a rotary ring of 16 nozzles. Nozzles are kept at two levels
(low and high) with respect to wheel and nozzle slit opening has three positions
45 vertical and horizontal.
TEMPERING
Untempered martensitic steel, while very hard, is too brittle to be useful for most
applications. A method for alleviating this problem is called tempering. Most
applications require that quenched parts be tempered.
Tempering consists of heating steel below the lower critical temperature, (often
from 400 to 1105 ˚F or 205 to 595 ˚C, depending on the desired results), to
impart some toughness. Higher tempering temperatures, (may be up to 1,300 ˚F
or 700 ˚C, depending on the alloy and application), are sometimes used to impart
further ductility, although some yield strength is lost.
Tempering may also be performed on normalized steels. Other methods of
tempering consist of quenching to a specific temperature, which is above the
martensite start temperature, and then holding it there until pure bainite can
form or internal stresses can be relieved. These include austempering and
martempering.
After rim quenching, the wheel goes to Draw Furnace for tempering. Through the
process of tempering, wheel is toughened at the expense of its hardness. Typically
as quenched hardness is 350-400 BHN. On tempering it reduces to a band of 280-
340 BHN.
- In this process the wheel is soaked at a temperature of 500-520 C for 120
mins. Wheels are moved in hooks which travel through the length of the DF.
- At any time DF holds 80 wheels i.e., the productivity is 1 wheel in 1.5 min.
- DF has eight zones and each zone id maintained at 500-520 C.
HUB QUENCHING
On discharge from Draw Furnace, the wheel goes through hub cooling. There
are three coolers and every wheel is cooled in all the stations. Hub cooling is
done to ensure a favourable residual stress pattern in the hub (mildly
compressive stress).
Following parameters are maintained during hub cooling
Waterpressure: 2.5 kgf/cm Water Temperature: 18 to 27 C
Time for cooling: a) BOX N: 45 sec at each station. b) BGC: 40 sec. at each station.
Each rim quencher has a rotary ring of 16 nozzles. Nozzles are kept at two levels
(low and high) with respect to wheel and nozzle slit opening has three positions
45 vertical and horizontal.
TEMPERING
Untempered martensitic steel, while very hard, is too brittle to be useful for most
applications. A method for alleviating this problem is called tempering. Most
applications require that quenched parts be tempered.
Tempering consists of heating steel below the lower critical temperature, (often
from 400 to 1105 ˚F or 205 to 595 ˚C, depending on the desired results), to
impart some toughness. Higher tempering temperatures, (may be up to 1,300 ˚F
or 700 ˚C, depending on the alloy and application), are sometimes used to impart
further ductility, although some yield strength is lost.
Tempering may also be performed on normalized steels. Other methods of
tempering consist of quenching to a specific temperature, which is above the
martensite start temperature, and then holding it there until pure bainite can
form or internal stresses can be relieved. These include austempering and
martempering.
After rim quenching, the wheel goes to Draw Furnace for tempering. Through the
process of tempering, wheel is toughened at the expense of its hardness. Typically
as quenched hardness is 350-400 BHN. On tempering it reduces to a band of 280-
340 BHN.
- In this process the wheel is soaked at a temperature of 500-520 C for 120
mins. Wheels are moved in hooks which travel through the length of the DF.
- At any time DF holds 80 wheels i.e., the productivity is 1 wheel in 1.5 min.
- DF has eight zones and each zone id maintained at 500-520 C.
HUB QUENCHING
On discharge from Draw Furnace, the wheel goes through hub cooling. There
are three coolers and every wheel is cooled in all the stations. Hub cooling is
done to ensure a favourable residual stress pattern in the hub (mildly
compressive stress).
Following parameters are maintained during hub cooling
Waterpressure: 2.5 kgf/cm Water Temperature: 18 to 27 C
Time for cooling: a) BOX N: 45 sec at each station. b) BGC: 40 sec. at each station.
Longer time in hub cooling decreases the closure value.
After hub cooling, wheels are off loaded and stacked in yard for air cooling.
After 12 hours of processing wheels are later processed at WFPS.
During the assembly of the wheels with axels there are chances of crack
formations in the hub portion. Hence this portion needs to be hardened.
- This hardening of the hub portion is done by Quenching Process.
- High pressure jet of water is sprayed only on the interior of the hub during
this process.
- Hence the hub portion becomes harder after this process and the chance of
crack portion is totally reduced.
The wheel after hub quenching has a rough surface and is air cooled. The
wheel need not be air cooled separately, they are sent into storage yard after
hub quenching. Wheels are taken from storage yard as and when required and
are subjected to further cleaning and finishing process.
WHEEL FINAL PROCESSING SHOP
Wheel is processed is Wheel Final Processing Shop (WFPS) formerly known as
Cleaning Shop. Wheels having been air cooled for 12 hours are picked up from
wheel yard and loaded in WFPS.
The Wheel coming out of the casting shop has a rough, uneven surface these
wheels need to be cleaned and finished before its usage. These cleaning,
finishing and certain tests are conducted in this cleaning shop.
The following major operations are carried out at the Wheel Final Process Shop:
• Apex Grinding and Plate Chipping.
• Wheel Cleaning Machine.
• Magna Glow Inspection.
• Ultrasonic Inspection.
• Hardness Tester (BHN).
• Warp age Testing.
• Wheel Penning.
• Hub Boring Machine.
• Final Inspection.
First operation on the wheel is apex grinding. Here any fin at apex of the flange
which is the parting like between cope and drag, is ground. For this purpose wheel
is given 1.25 rotations, time required is 45 secs. The surface of the wheel may
After hub cooling, wheels are off loaded and stacked in yard for air cooling.
After 12 hours of processing wheels are later processed at WFPS.
During the assembly of the wheels with axels there are chances of crack
formations in the hub portion. Hence this portion needs to be hardened.
- This hardening of the hub portion is done by Quenching Process.
- High pressure jet of water is sprayed only on the interior of the hub during
this process.
- Hence the hub portion becomes harder after this process and the chance of
crack portion is totally reduced.
The wheel after hub quenching has a rough surface and is air cooled. The
wheel need not be air cooled separately, they are sent into storage yard after
hub quenching. Wheels are taken from storage yard as and when required and
are subjected to further cleaning and finishing process.
WHEEL FINAL PROCESSING SHOP
Wheel is processed is Wheel Final Processing Shop (WFPS) formerly known as
Cleaning Shop. Wheels having been air cooled for 12 hours are picked up from
wheel yard and loaded in WFPS.
The Wheel coming out of the casting shop has a rough, uneven surface these
wheels need to be cleaned and finished before its usage. These cleaning,
finishing and certain tests are conducted in this cleaning shop.
The following major operations are carried out at the Wheel Final Process Shop:
• Apex Grinding and Plate Chipping.
• Wheel Cleaning Machine.
• Magna Glow Inspection.
• Ultrasonic Inspection.
• Hardness Tester (BHN).
• Warp age Testing.
• Wheel Penning.
• Hub Boring Machine.
• Final Inspection.
First operation on the wheel is apex grinding. Here any fin at apex of the flange
which is the parting like between cope and drag, is ground. For this purpose wheel
is given 1.25 rotations, time required is 45 secs. The surface of the wheel may
contain dirt, ashes and even dust particles formed during storing; also the
wheels contain scales formed during heat treatment process. This unwanted
dust must be removed In order to obtain a clean surfaced wheel. Steel blasting is
the first process carried out in the cleaning shop. In this process, tiny spherical
metal shots with high velocity are made to strike the surface of the wheel.
Next the wheel moves on to wheel cleaning machine. Here high velocity steel
shots are impinged on the rotating wheel. Three root-blasting units blast the
shots; one each towards cope side, drag side and thread. Thorough cleaning of
wheels off any scale, spray coating and corrosion product is ensured here.
Due to the impact of these particles the surface dust present on the wheel gets
removed due to the abrasive action. Hence the surface cleaned wheel is
obtained after this steel blasting process.
After this steel blasting, the wheel is made to undergo two tests namely Ultra
Sonic test and Magna glow test. Only those wheels passed in these test are sent
to further processing and the wheels with defects are sent back to machining
accordingly. The rejected wheels are sent to scrap yard and is recycled.
Now the wheel moves to dark room for non-destructive testing (NDT) through
magna glow, ultrasonic and BHN testing followed by warpage testing.
Wheels having minor defects on plate like crack, inclusions of slag, refractory,
sand, graphite, asbestos or spray which can be easily removed through surface
grinding are sent to grinding like. If grinding operation up to a depth of 3 mm is
not likely to remove the defect, the wheel is marked for machining. The wheels
are sent for magna glow testing again. Then wheels pass through war page
stations to penning machine.
PEENING:
Wheel is penned on the plate area; both cope and drag sides to improve fatigue
life. Through shot peening, the skin of wheel plate is stretched beyond yield and
thereby residual compressive stress is imparted on skin layer. Two nos. roto blast
units one each on cope and drag side similar to those of cleaning machines are
used.
HUB BORING:
Now the wheel is taken up for hub boring. This is the rough boring operation
carried out on the wheel before it is sent into assembly shop. During hub
cutting, the centre hole generated is of a smaller diameter when compared to
the required diameter.
This hole need to be enlarged for the axle to fit in. This hole enlarging is done
wheels contain scales formed during heat treatment process. This unwanted
dust must be removed In order to obtain a clean surfaced wheel. Steel blasting is
the first process carried out in the cleaning shop. In this process, tiny spherical
metal shots with high velocity are made to strike the surface of the wheel.
Next the wheel moves on to wheel cleaning machine. Here high velocity steel
shots are impinged on the rotating wheel. Three root-blasting units blast the
shots; one each towards cope side, drag side and thread. Thorough cleaning of
wheels off any scale, spray coating and corrosion product is ensured here.
Due to the impact of these particles the surface dust present on the wheel gets
removed due to the abrasive action. Hence the surface cleaned wheel is
obtained after this steel blasting process.
After this steel blasting, the wheel is made to undergo two tests namely Ultra
Sonic test and Magna glow test. Only those wheels passed in these test are sent
to further processing and the wheels with defects are sent back to machining
accordingly. The rejected wheels are sent to scrap yard and is recycled.
Now the wheel moves to dark room for non-destructive testing (NDT) through
magna glow, ultrasonic and BHN testing followed by warpage testing.
Wheels having minor defects on plate like crack, inclusions of slag, refractory,
sand, graphite, asbestos or spray which can be easily removed through surface
grinding are sent to grinding like. If grinding operation up to a depth of 3 mm is
not likely to remove the defect, the wheel is marked for machining. The wheels
are sent for magna glow testing again. Then wheels pass through war page
stations to penning machine.
PEENING:
Wheel is penned on the plate area; both cope and drag sides to improve fatigue
life. Through shot peening, the skin of wheel plate is stretched beyond yield and
thereby residual compressive stress is imparted on skin layer. Two nos. roto blast
units one each on cope and drag side similar to those of cleaning machines are
used.
HUB BORING:
Now the wheel is taken up for hub boring. This is the rough boring operation
carried out on the wheel before it is sent into assembly shop. During hub
cutting, the centre hole generated is of a smaller diameter when compared to
the required diameter.
This hole need to be enlarged for the axle to fit in. This hole enlarging is done
by the boring process.
- A square shaped carbide tool is used for this operation
- The hole of 5-10 mm lesser than the axle wheel seat diameter is produced
during this process.
- The hole produced has a rough surface finish.
- BOX N wheel is bored to 205 mm dia and BGC wheel is bored to 168 mm dia.
WARPAGING:
The wheels during casting and heat treatment process remains at high
temperature. Wheels are kept horizontally on war page stations back side up.
Four nos. laser transducers check the war page at back flange. During this high
temperature there are chances of wheel undergoing a little bending. But this
bending of wheels above certain limits is undesirable for the working of the
wheel.
The War paging process includes the balancing of the wheels from which the
defects relating to the shape of the wheels can be detected. If the detected
defects in the shape like bending of wheels etc. are more than the limiting value,
wheels are rejected. Permissible war page is 1 mm.
- A square shaped carbide tool is used for this operation
- The hole of 5-10 mm lesser than the axle wheel seat diameter is produced
during this process.
- The hole produced has a rough surface finish.
- BOX N wheel is bored to 205 mm dia and BGC wheel is bored to 168 mm dia.
WARPAGING:
The wheels during casting and heat treatment process remains at high
temperature. Wheels are kept horizontally on war page stations back side up.
Four nos. laser transducers check the war page at back flange. During this high
temperature there are chances of wheel undergoing a little bending. But this
bending of wheels above certain limits is undesirable for the working of the
wheel.
The War paging process includes the balancing of the wheels from which the
defects relating to the shape of the wheels can be detected. If the detected
defects in the shape like bending of wheels etc. are more than the limiting value,
wheels are rejected. Permissible war page is 1 mm.
AXLE SHOP
The second unit of RWF is axle shop where the railway axles are produced.
An axle is a cylindrical rod on which the wheels of locomotives are seated and
hence helps to maintain the distance between the 2 wheels.
RWF buys high-quality vacuum degassed steel blooms from large-scale
steelmakers. Axles are manufactured from billets cut from the blooms. These
blooms are forged in a precision long-forging machine supplied from M/s GFM,
Austria. The billets are heated in a rotary hearth furnace to forging
temperatures. Billets then forged in axles on a special purpose long forging
machine. The forged axles are gas cut to required length. The axles are heat
treated through various heat treatment processes. The physical properties are
confirmed before machining of the axles. The forged axles are machined on
various machines. The operations include end machining, rough turning, finish
turning, machining centers, grinding and burnishing.
The railway axle is a long thick cylindrical rod made up of alloy steel and weighs
about 500 kg, The axles mainly consists of 4 parts namely Body Wheel seat, Dust
guard and Journal. Major portion of the axle is the body whose length is fixed
and is equal the distance to be maintained between two parallel wheels. Hence
the length of the body which is the centre portion of the axle varies for different
types of axle.
The portion of the axle where the wheels of the train is fixed is the wheel seat.
The diameter and the length of the wheel seat are completely based on the
diameter of the bore in the wheel and its thickness. The curved portion in
between the wheel seat and the journal is the dust guard. The two ends of the
axle are after the dust guard is called the journal.
The journal is the main portion which is required in a perfect smooth finished
surface state. The bearings of the train wheels occupy this place. In RWF the
axle shop is divided into three portions where different operations are
performed on the axle.
The three portions are
1) Forging Shop
2) Machining Shop
3) Assembly Shop
- The blooms are cut and are given the shape of axle by forging and later heat
treated in the forging shop.
- The axles to the required dimensions are machined in the machining shop.
Certain tests done to check cracks.
- The finished axles are assembled along with wheels in the assembly shop.
An axle is a cylindrical rod on which the wheels of locomotives are seated and
hence helps to maintain the distance between the 2 wheels.
RWF buys high-quality vacuum degassed steel blooms from large-scale
steelmakers. Axles are manufactured from billets cut from the blooms. These
blooms are forged in a precision long-forging machine supplied from M/s GFM,
Austria. The billets are heated in a rotary hearth furnace to forging
temperatures. Billets then forged in axles on a special purpose long forging
machine. The forged axles are gas cut to required length. The axles are heat
treated through various heat treatment processes. The physical properties are
confirmed before machining of the axles. The forged axles are machined on
various machines. The operations include end machining, rough turning, finish
turning, machining centers, grinding and burnishing.
The railway axle is a long thick cylindrical rod made up of alloy steel and weighs
about 500 kg, The axles mainly consists of 4 parts namely Body Wheel seat, Dust
guard and Journal. Major portion of the axle is the body whose length is fixed
and is equal the distance to be maintained between two parallel wheels. Hence
the length of the body which is the centre portion of the axle varies for different
types of axle.
The portion of the axle where the wheels of the train is fixed is the wheel seat.
The diameter and the length of the wheel seat are completely based on the
diameter of the bore in the wheel and its thickness. The curved portion in
between the wheel seat and the journal is the dust guard. The two ends of the
axle are after the dust guard is called the journal.
The journal is the main portion which is required in a perfect smooth finished
surface state. The bearings of the train wheels occupy this place. In RWF the
axle shop is divided into three portions where different operations are
performed on the axle.
The three portions are
1) Forging Shop
2) Machining Shop
3) Assembly Shop
- The blooms are cut and are given the shape of axle by forging and later heat
treated in the forging shop.
- The axles to the required dimensions are machined in the machining shop.
Certain tests done to check cracks.
- The finished axles are assembled along with wheels in the assembly shop.
FORGING SHOP
Forging is a manufacturing process involving the shaping of metal using localized
compressive forces. Forging is often classified according to the temperature at
which it is performed: "cold", "warm", or "hot" forging. Forged parts can range in
weight from less than a kilogram to 580 metric tons. Forged parts usually require
further processing to achieve a finished part. Today, forging is a major world-
wide industry that has significantly contributed to the development of the
manufacturing cycles.
Forging can produce a piece that is stronger than an equivalent cast or machined
part. As the metal is shaped during the forging process, its internal grain deforms
to follow the general shape of the part. As a result, the grain is continuous
throughout the part, giving rise to a piece with improved strength characteristics.
In RWF the axle are produced by forging process. Here the long blooms are cut
into small piece called billets which are later given the shape of the axle by
forging.
Forging, because of its inherent improvement in the grain size and introduction
of uninterrupted grain flow in the finished Component has the following
advantages:
Greater toughness and strength
Reduction of weight of the finished part.
Saving in the material.
Elimination internal defects, such as cracks, porosity, blow holes etc.
Ability to with stand unpredictable loads during service.
Minimum machining to be done for the work piece.
There are many different kinds of forging processes available; however they
can be grouped into three main classes.
Drawn out: length increases, cross-section decreases
Upset: length decreases, cross-section increases
Squeezed in closed compression dies: produces multidirectional flow
Bloom
Forging is a manufacturing process involving the shaping of metal using localized
compressive forces. Forging is often classified according to the temperature at
which it is performed: "cold", "warm", or "hot" forging. Forged parts can range in
weight from less than a kilogram to 580 metric tons. Forged parts usually require
further processing to achieve a finished part. Today, forging is a major world-
wide industry that has significantly contributed to the development of the
manufacturing cycles.
Forging can produce a piece that is stronger than an equivalent cast or machined
part. As the metal is shaped during the forging process, its internal grain deforms
to follow the general shape of the part. As a result, the grain is continuous
throughout the part, giving rise to a piece with improved strength characteristics.
In RWF the axle are produced by forging process. Here the long blooms are cut
into small piece called billets which are later given the shape of the axle by
forging.
Forging, because of its inherent improvement in the grain size and introduction
of uninterrupted grain flow in the finished Component has the following
advantages:
Greater toughness and strength
Reduction of weight of the finished part.
Saving in the material.
Elimination internal defects, such as cracks, porosity, blow holes etc.
Ability to with stand unpredictable loads during service.
Minimum machining to be done for the work piece.
There are many different kinds of forging processes available; however they
can be grouped into three main classes.
Drawn out: length increases, cross-section decreases
Upset: length decreases, cross-section increases
Squeezed in closed compression dies: produces multidirectional flow
Bloom
Cutting
RWF makes axles for locomotives, coaches, wagons, crane & EMUs. Axle
blooms are procured from market. To avoid wastage, blooms are procured in
multiple length of unit billet length for each type of axle.
The long bar with square cross section called Blooms are cut into small length
pieces called Billets by Gas cutting. The fuel used is Oxygen + LPG Gas (Propane
gas). The gas flame with a pressure of about 10 bars is directed on the work
piece and cutting action is performed. The cutting is based on length to weight
ratio.
Heating
Blooms are heated in Rotary Hearth Furnace before being fed into forging
machine. Rotary Hearth Furnace is a two shell structure, one outer and another
inner. It is of oil fired type.
The billets after being cut must be heated so that it can be forged. The Rotary
Health Furnace having four zones namely Pre-heating zone, heating zone,
soaking zone 1 and soaking zone 2 is used for heating the billets to a
temperature of about 1185 - 1200 degree Celsius. The billet first enters the pre-
heating zone where the heating process begins. Further it moves to the heating
zone. In the soaking zone 1 and 2 is the spread to the core of the work piece. The
fuel used is High Speed Diesel (HSD). The pressure inside the RHF is set to 10 bars.
The temperature of the flue gas coming out of RHF is around 600 degree Celsius.
The hearth carrying billets rotates in all the 4 zones. The capacity of the hearth is
80 billets.
The furnace is fitted with 20 burners, fume extraction system, water troughs,
measuring instruments etc. Gas fumes extracted from the furnace is used to
preheat the incoming air in recuperator unit. Billets are charged and discharged
with charging and discharging the machine.
RWF makes axles for locomotives, coaches, wagons, crane & EMUs. Axle
blooms are procured from market. To avoid wastage, blooms are procured in
multiple length of unit billet length for each type of axle.
The long bar with square cross section called Blooms are cut into small length
pieces called Billets by Gas cutting. The fuel used is Oxygen + LPG Gas (Propane
gas). The gas flame with a pressure of about 10 bars is directed on the work
piece and cutting action is performed. The cutting is based on length to weight
ratio.
Heating
Blooms are heated in Rotary Hearth Furnace before being fed into forging
machine. Rotary Hearth Furnace is a two shell structure, one outer and another
inner. It is of oil fired type.
The billets after being cut must be heated so that it can be forged. The Rotary
Health Furnace having four zones namely Pre-heating zone, heating zone,
soaking zone 1 and soaking zone 2 is used for heating the billets to a
temperature of about 1185 - 1200 degree Celsius. The billet first enters the pre-
heating zone where the heating process begins. Further it moves to the heating
zone. In the soaking zone 1 and 2 is the spread to the core of the work piece. The
fuel used is High Speed Diesel (HSD). The pressure inside the RHF is set to 10 bars.
The temperature of the flue gas coming out of RHF is around 600 degree Celsius.
The hearth carrying billets rotates in all the 4 zones. The capacity of the hearth is
80 billets.
The furnace is fitted with 20 burners, fume extraction system, water troughs,
measuring instruments etc. Gas fumes extracted from the furnace is used to
preheat the incoming air in recuperator unit. Billets are charged and discharged
with charging and discharging the machine.
Forging
Axle is forged in Long Forging Machine. The LFM is a multiple head power
hammer operating on the “Swaging principle”. Swaging is a special type of
forging in which metal is formed by rapid succession of hammer blows. It is one
of the most economical methods ever employed to point tubing, rod, and wire
for redraw- and to size, shape, reduce, taper and bond or for metal parts, hot or
cold. Metal is formed- not machined- so there are no wasteful chips. Swaging
actually improves grain structure giving the part greater strength and an
unusually fine finish.
Axle is forged in Long Forging Machine. The LFM is a multiple head power
hammer operating on the “Swaging principle”. Swaging is a special type of
forging in which metal is formed by rapid succession of hammer blows. It is one
of the most economical methods ever employed to point tubing, rod, and wire
for redraw- and to size, shape, reduce, taper and bond or for metal parts, hot or
cold. Metal is formed- not machined- so there are no wasteful chips. Swaging
actually improves grain structure giving the part greater strength and an
unusually fine finish.
Forging is the process that involves deforming of hot metal piece to a desired
shape using compressive forces. The force may be impact type, like a blow from
a hammer or a squeeze type, like that of Hydraulic press. For forging, the work
piece is heated to a proper temperature so that it gains required plastic
properties before deformation. The hammers operate through power and the
pressure; is applied using hydraulics.
During operation the temperature of the billet will be around 1180- 1200 degree
Celsius and at this temperature it is forged into the required axle shape. The
hammers are made of special steel alloy and hence water is sprayed during
operation so that the hammer does not wear out. Heated billet at 1200 C is
taken out from Rotary Hearth Furnace and passed on to Long Forging Machine
through the conveyor system.
- The billet is then handed over to the Long Forging Machine by means of a
loading machine.
- The billet is held between the jaws of chuck and in brought into the forging
box and the forging starts.
- The programmed sequence of operation is carried out.
- Each type of axle has a different programmed sequence.
- The hot billet rotates during forging operation.
- Air mixed with water in the form of jet is sprayed on the hammers to keep
them cool as well as to blow out the scaled formed on the forging billets.
- The forging ratio is 2:1.
- The forging is over; the axle is unloaded from the long forging machine.
Machining Shop
END CUTTING
While forging the metal, the top layer of axle ends flows along the surface of
the axle and gets collected at the ends in the forms of fish tail and as a result
piping is formed. To eliminate this tailed structure piping and in order to
maintain the exact length of the axle, the ends of the axle are cropped using an
oxygen + high propane type end cutting machine. Approximately 58 kgs of
metal is taken out in this cutting. The forged axles arrive from the conveyor of
the Forging Machine to feed roller conveyor of the cutting equipment. The axles
are driven with this conveyor exactly into the location of the position indicators
or pointers. The axle positioned in this manner is kept below the cutting
equipment with the axle lifting device. The end cutting machine consists of two
gas torch whose centre distance can be adjusted depending up on the actual
axle length. The required oxy- acetylene gas at high pressure is used to cut the
axle which is still at a higher temperature (1000 C). During operation, the two
torches are fixed to a centre distance equal to the sum of required length,
shrinkage length) and the torch thickness and cutting performed. The high
shape using compressive forces. The force may be impact type, like a blow from
a hammer or a squeeze type, like that of Hydraulic press. For forging, the work
piece is heated to a proper temperature so that it gains required plastic
properties before deformation. The hammers operate through power and the
pressure; is applied using hydraulics.
During operation the temperature of the billet will be around 1180- 1200 degree
Celsius and at this temperature it is forged into the required axle shape. The
hammers are made of special steel alloy and hence water is sprayed during
operation so that the hammer does not wear out. Heated billet at 1200 C is
taken out from Rotary Hearth Furnace and passed on to Long Forging Machine
through the conveyor system.
- The billet is then handed over to the Long Forging Machine by means of a
loading machine.
- The billet is held between the jaws of chuck and in brought into the forging
box and the forging starts.
- The programmed sequence of operation is carried out.
- Each type of axle has a different programmed sequence.
- The hot billet rotates during forging operation.
- Air mixed with water in the form of jet is sprayed on the hammers to keep
them cool as well as to blow out the scaled formed on the forging billets.
- The forging ratio is 2:1.
- The forging is over; the axle is unloaded from the long forging machine.
Machining Shop
END CUTTING
While forging the metal, the top layer of axle ends flows along the surface of
the axle and gets collected at the ends in the forms of fish tail and as a result
piping is formed. To eliminate this tailed structure piping and in order to
maintain the exact length of the axle, the ends of the axle are cropped using an
oxygen + high propane type end cutting machine. Approximately 58 kgs of
metal is taken out in this cutting. The forged axles arrive from the conveyor of
the Forging Machine to feed roller conveyor of the cutting equipment. The axles
are driven with this conveyor exactly into the location of the position indicators
or pointers. The axle positioned in this manner is kept below the cutting
equipment with the axle lifting device. The end cutting machine consists of two
gas torch whose centre distance can be adjusted depending up on the actual
axle length. The required oxy- acetylene gas at high pressure is used to cut the
axle which is still at a higher temperature (1000 C). During operation, the two
torches are fixed to a centre distance equal to the sum of required length,
shrinkage length) and the torch thickness and cutting performed. The high
pressure gas flame is brought near the work piece which is held by stands.
Water is not used as the work piece is still in red hot condition and spraying may
results in the formation of cracks. Once the excess material is cut off axle is then
sent for stamping operation.
STAMPING
After end cutting the axle is taken to stamping machine. In this process the
stamping machine punches stamps the axle with numbers which includes
different coding .Following details are stamped.
RWF 14 A 1234
RWF => Manufacturers code
2014=> Year of manufacture
A=> Manufacturers series A to Z
1234=> Serial number.
The time required for stamping is 2 min approx.
COOLING:
After end cutting and stamping the axle is still at high temperature. In order to
do further processing and enhance the properties of the axle, it must be
cooled. Air cooling helps the axle to loose heat by radiation. There are two
conveyor type cooling beds, having a capacity to hold 30 axles each.
A hand over equipment takes the axle from cooling bed and positions in the
Normalizing furnace. The conveyor swivels 90 C on pivotal movement and
hands over the axle to the Normalizing furnace.
AXLE QUENCHING:
Not all types of axles require quenching. Only a few types of diesel axles are
quenched in quenching agent (polymer oil) and this is called Polymer Quenching.
The axles requiring quenching are brought in a batch of 5 axle to the quench
elevator. The elevator then carries the axles to the quenching tank and brings
back the axles after dipping them in the polymer quench ant for pre-
determined duration, generally 30 min.
Quenching is defined as sudden cooling of heated steel (metal) by dipping in cooling
agent or spraying cooling agent in order to obtain the work piece in a stable state
which induces certain properties like hardness etc to the work piece material. A
mixture of polymer oil and water in the ratio 1:20 is used as quenching agent in
forging shop of RWF.
Water is not used as the work piece is still in red hot condition and spraying may
results in the formation of cracks. Once the excess material is cut off axle is then
sent for stamping operation.
STAMPING
After end cutting the axle is taken to stamping machine. In this process the
stamping machine punches stamps the axle with numbers which includes
different coding .Following details are stamped.
RWF 14 A 1234
RWF => Manufacturers code
2014=> Year of manufacture
A=> Manufacturers series A to Z
1234=> Serial number.
The time required for stamping is 2 min approx.
COOLING:
After end cutting and stamping the axle is still at high temperature. In order to
do further processing and enhance the properties of the axle, it must be
cooled. Air cooling helps the axle to loose heat by radiation. There are two
conveyor type cooling beds, having a capacity to hold 30 axles each.
A hand over equipment takes the axle from cooling bed and positions in the
Normalizing furnace. The conveyor swivels 90 C on pivotal movement and
hands over the axle to the Normalizing furnace.
AXLE QUENCHING:
Not all types of axles require quenching. Only a few types of diesel axles are
quenched in quenching agent (polymer oil) and this is called Polymer Quenching.
The axles requiring quenching are brought in a batch of 5 axle to the quench
elevator. The elevator then carries the axles to the quenching tank and brings
back the axles after dipping them in the polymer quench ant for pre-
determined duration, generally 30 min.
Quenching is defined as sudden cooling of heated steel (metal) by dipping in cooling
agent or spraying cooling agent in order to obtain the work piece in a stable state
which induces certain properties like hardness etc to the work piece material. A
mixture of polymer oil and water in the ratio 1:20 is used as quenching agent in
forging shop of RWF.
INTERMEDIATE COOLING:
Normalised/quenched axle is air cooled on intermediate cooling bed (ICB) from
860 C to 300 C before being fed into tempering furnace. ICB is a hydraulically
operated walking beam conveyor system, having two fixed beams and one
moving beam.
TEMPERING
Axle from Intermediate cooling bed goes to tempering done at a temperature
of 650 C. Tempering has a capacity to hold 118 axle. The axle movement is
similar to that of normalizing furnace. It is necessary to return towards
equilibrium after quench hardening, by heating the steel to a temperature
below the critical temperature. This is tempering. Tempering also reduces the
internal stresses in the axles which may have induced during heating, forging
or quenching.
Machining Shop
The axle coming out of Forging Chamber are of dimension greater than
required, only rough shape and have very rough surface. These axles cannot be
used directly. Hence in order to obtain exact dimensional, required shape and
a perfect surface finish machining has to be carried out.
Machining is any of various processes in which a piece of raw material is cut into a
desired final shape and size by a controlled material-removal process.
The many processes that have this common theme, controlled material
removal, are today collectively known as subtractive manufacturing, in
distinction from processes of controlled material addition, which are known as
additive manufacturing. Exactly what the "controlled" part of the definition
implies can vary, but it almost always implies the use of machine tools (in
addition to just power tools and hand tools).
Metal cutting is a process of removing a layer of material from the metal blank
by means of a tool, which is harder than the metal being cut. The layer of metal
is removed is called as chip and this removal is due to plastic deformation or
controlled fracture in the metal blank.
Normalised/quenched axle is air cooled on intermediate cooling bed (ICB) from
860 C to 300 C before being fed into tempering furnace. ICB is a hydraulically
operated walking beam conveyor system, having two fixed beams and one
moving beam.
TEMPERING
Axle from Intermediate cooling bed goes to tempering done at a temperature
of 650 C. Tempering has a capacity to hold 118 axle. The axle movement is
similar to that of normalizing furnace. It is necessary to return towards
equilibrium after quench hardening, by heating the steel to a temperature
below the critical temperature. This is tempering. Tempering also reduces the
internal stresses in the axles which may have induced during heating, forging
or quenching.
Machining Shop
The axle coming out of Forging Chamber are of dimension greater than
required, only rough shape and have very rough surface. These axles cannot be
used directly. Hence in order to obtain exact dimensional, required shape and
a perfect surface finish machining has to be carried out.
Machining is any of various processes in which a piece of raw material is cut into a
desired final shape and size by a controlled material-removal process.
The many processes that have this common theme, controlled material
removal, are today collectively known as subtractive manufacturing, in
distinction from processes of controlled material addition, which are known as
additive manufacturing. Exactly what the "controlled" part of the definition
implies can vary, but it almost always implies the use of machine tools (in
addition to just power tools and hand tools).
Metal cutting is a process of removing a layer of material from the metal blank
by means of a tool, which is harder than the metal being cut. The layer of metal
is removed is called as chip and this removal is due to plastic deformation or
controlled fracture in the metal blank.
Cutting Tool and Chip Formation:
A cutting tool (or cutter) is any tool that is used to remove material from the
work piece by means of shear deformation. Cutting may be accomplished by
single-point or multipoint tools.
Single-point tools are used in turning, shaping, plaining and similar operations,
and remove material by means of one cutting edge. Milling and drilling tools are
often multipoint tools. Grinding tools are also multipoint tools. Each grain of
abrasive functions as a microscopic single-point cutting edge (although of high
negative rake angle), and shears a tiny chip.
Coolants:
During metal cutting extensive heat is generated due to the friction between
the tool and work piece Also, as the chips slides up the tool face, heat is
generated due to friction at the contact points between chip and tool face. The
excessive heat thus generated can damage the microstructure of both the
cutting tool and the work piece. In order to reduce the effect of friction or heat
generated, Cutting fluids are used.
Cutting fluid is a type of coolant and lubricant designed specifically for
metalworking and machining processes. There are various kinds of cutting
fluids, which include oils, oil-water emulsions, pastes, gels, aerosols (mists),
and air or other gases. They may be made from petroleum distillates, animal
fats, plant oils, water and air, or other raw ingredients. Depending on context
and on which type of cutting fluid is being considered, it may be referred to as
cutting fluid, cutting oil, cutting compound, coolant, or lubricant.
CNC Machine:
Numerical control (NC) is the automation of machine tools that are operated
by precisely programmed commands encoded on a storage medium, as
opposed to controlled manually via hand wheels or levers, or mechanically
automated via cams alone. Most NC today is computer numerical control
(CNC), in which computers play an integral part of the control.
A cutting tool (or cutter) is any tool that is used to remove material from the
work piece by means of shear deformation. Cutting may be accomplished by
single-point or multipoint tools.
Single-point tools are used in turning, shaping, plaining and similar operations,
and remove material by means of one cutting edge. Milling and drilling tools are
often multipoint tools. Grinding tools are also multipoint tools. Each grain of
abrasive functions as a microscopic single-point cutting edge (although of high
negative rake angle), and shears a tiny chip.
Coolants:
During metal cutting extensive heat is generated due to the friction between
the tool and work piece Also, as the chips slides up the tool face, heat is
generated due to friction at the contact points between chip and tool face. The
excessive heat thus generated can damage the microstructure of both the
cutting tool and the work piece. In order to reduce the effect of friction or heat
generated, Cutting fluids are used.
Cutting fluid is a type of coolant and lubricant designed specifically for
metalworking and machining processes. There are various kinds of cutting
fluids, which include oils, oil-water emulsions, pastes, gels, aerosols (mists),
and air or other gases. They may be made from petroleum distillates, animal
fats, plant oils, water and air, or other raw ingredients. Depending on context
and on which type of cutting fluid is being considered, it may be referred to as
cutting fluid, cutting oil, cutting compound, coolant, or lubricant.
CNC Machine:
Numerical control (NC) is the automation of machine tools that are operated
by precisely programmed commands encoded on a storage medium, as
opposed to controlled manually via hand wheels or levers, or mechanically
automated via cams alone. Most NC today is computer numerical control
(CNC), in which computers play an integral part of the control.
CNC Station 1 : End Milling, Centring & Cup Turning:
The rough surface axle coming from the forging shop is sent to the
machining shop where in the first station End milling, Centring and Cup
turning operations are carried out.
- The forged axle after undergoing various heat treatment process will have
excess length and this must be cut to the required length with little amount
of tolerance which is left for further machining.
- This excess material is removed by milling operation. The excess material is
removed at the ends of the axle hence called as end milling.
Milling is a manufacturing process in which excess material from the work
piece is removed by a rotating multi point cutting tool called milling cutter.
The multipoint milling tool consists of number of inserts which does the
actual cutting job. During operation the stationary work piece is brought near
to the high speed rotating milling cutter rotating at 350 rpm which removes
the excess material.
The inserts used for milling are made up of Carbide and have 4 cutting edges.
Centring is producing a centre hole in the axle in order to hold the work piece
for further machining processes.
Centring is followed by cup turning where the excess material is
removed and given surface finish at the ends. Both the centring and cup
turning tool are made of High Speed Steel. The speed, feed and depth
of cut depends on the type of the axle to be machined.
After this an Ultrasonic test is done to detect the vertical cracks.
CNC Station 2 -Rough Turning
After the completion of the End Milling, Centring and Cup Turning and the UV
Test, the axle comes to Station 2 where Rough Turning takes place. Turning is a
machining process where the external surface of the Work piece is machined
by means of a Stationary Traversing Tool and the work piece being rotated.The
forged axle has scales and excess material on its surface, in order to remove
this excess material the rough turning operation is done.The exact shape of the
axle is obtained in this process and the surface is being very rough after the
machining as the name indicates. During operation the axle is fixed between
the chucks and made to rotate at a very high speed. The tool having 8 cutting
The rough surface axle coming from the forging shop is sent to the
machining shop where in the first station End milling, Centring and Cup
turning operations are carried out.
- The forged axle after undergoing various heat treatment process will have
excess length and this must be cut to the required length with little amount
of tolerance which is left for further machining.
- This excess material is removed by milling operation. The excess material is
removed at the ends of the axle hence called as end milling.
Milling is a manufacturing process in which excess material from the work
piece is removed by a rotating multi point cutting tool called milling cutter.
The multipoint milling tool consists of number of inserts which does the
actual cutting job. During operation the stationary work piece is brought near
to the high speed rotating milling cutter rotating at 350 rpm which removes
the excess material.
The inserts used for milling are made up of Carbide and have 4 cutting edges.
Centring is producing a centre hole in the axle in order to hold the work piece
for further machining processes.
Centring is followed by cup turning where the excess material is
removed and given surface finish at the ends. Both the centring and cup
turning tool are made of High Speed Steel. The speed, feed and depth
of cut depends on the type of the axle to be machined.
After this an Ultrasonic test is done to detect the vertical cracks.
CNC Station 2 -Rough Turning
After the completion of the End Milling, Centring and Cup Turning and the UV
Test, the axle comes to Station 2 where Rough Turning takes place. Turning is a
machining process where the external surface of the Work piece is machined
by means of a Stationary Traversing Tool and the work piece being rotated.The
forged axle has scales and excess material on its surface, in order to remove
this excess material the rough turning operation is done.The exact shape of the
axle is obtained in this process and the surface is being very rough after the
machining as the name indicates. During operation the axle is fixed between
the chucks and made to rotate at a very high speed. The tool having 8 cutting
edged is fed against this rotating axle which removes the excess material in the
form of chips. The material is removed from both the edged simultaneously i.e.
the turning operation makes use of 2 tool at the same time in order to reduce
the time of operation. In Rail Wheel Factory (RWF) axle machining shop rough
turning is done by both CNC lathes and conventional lathe. In the CNC lathe
the feed, the motion of the tool spindle/holder for each type of axle is
programmed and fed into the computer which guides the cutting operation.
Various parameters like length of the axle, feed, diameter of the axle, speed of
rotation etc can be adjusted and altered by the operator as and when
required. A tracer placed in the carriage traces the template, tool carriage and
hence the tool moves along the same shape, hence the required shape is
obtained on the axle. Each parameter like feed, speed, carriage movement etc
can be controlled by the operator. The process can also be automated and can
be stopped and adjusted at any point of time.
CNC STATION 3 – Drilling, Reaming & Tapping
After rough turning of the axle, threaded holes are drilled at the two ends
surfaces in order to fix the bearing to the axle.
Drilling:
Drilling is a machining operation of producing a cylindrical hole in a solid
work piece by means of a revolving tool called the Drill bit. Drill bit is also
called as twist drill since it has sharp twisted edges formed around a cylindrical
body. In operation, the drill bit is held in the chuck of the machine and rotated
by a spindle at high speed. With the help of the hand wheel or by automatic
means, the drill bit is forced to move against the rigidly clamped work piece.
The hole is generated by the sharp cutting edges of the rotating drill bit while
the excess material removed (chips) gets curled and escapes through the
helical grooves provided in the drill bit. Since the cutting action takes place
inside the work piece, lot of heat is generated: this may cause damage to the
form of chips. The material is removed from both the edged simultaneously i.e.
the turning operation makes use of 2 tool at the same time in order to reduce
the time of operation. In Rail Wheel Factory (RWF) axle machining shop rough
turning is done by both CNC lathes and conventional lathe. In the CNC lathe
the feed, the motion of the tool spindle/holder for each type of axle is
programmed and fed into the computer which guides the cutting operation.
Various parameters like length of the axle, feed, diameter of the axle, speed of
rotation etc can be adjusted and altered by the operator as and when
required. A tracer placed in the carriage traces the template, tool carriage and
hence the tool moves along the same shape, hence the required shape is
obtained on the axle. Each parameter like feed, speed, carriage movement etc
can be controlled by the operator. The process can also be automated and can
be stopped and adjusted at any point of time.
CNC STATION 3 – Drilling, Reaming & Tapping
After rough turning of the axle, threaded holes are drilled at the two ends
surfaces in order to fix the bearing to the axle.
Drilling:
Drilling is a machining operation of producing a cylindrical hole in a solid
work piece by means of a revolving tool called the Drill bit. Drill bit is also
called as twist drill since it has sharp twisted edges formed around a cylindrical
body. In operation, the drill bit is held in the chuck of the machine and rotated
by a spindle at high speed. With the help of the hand wheel or by automatic
means, the drill bit is forced to move against the rigidly clamped work piece.
The hole is generated by the sharp cutting edges of the rotating drill bit while
the excess material removed (chips) gets curled and escapes through the
helical grooves provided in the drill bit. Since the cutting action takes place
inside the work piece, lot of heat is generated: this may cause damage to the
tool as well as the work piece. Hence coolant is used to reduce the heat. Both
the ends are drilled at the same time.
Reaming
Reaming is the operation of finishing a previously drilled hole to bring it to
an exact size and to improve the surface finish of the hole. The operation is
earned out using a multi tooth revolving tool caller Reamer, which consists of a
set of parallel straight or helical cutting edges along the length of the cylindrical
tool. This operation is carried out at a speed lower than drilling in order to obtain a
good surface finish.
Tapping
Tapping is the operation of producing internal threads in a previously
drilled hole by means of a tool called tap. The tap has threads cut on its periphery
and is hardened to improve its properties. The threads cut on the tap form the
replica of the threads to be produced in the work piece. To generate a specific
size thread in the work piece, a hole with diameter smaller than the size of the
tap is first drilled using twist drill. To perform the tapping operation, the tool is
held rigidly in the spindle and is rotated at a speed less than drilling operation. The
rotating tap is fed slowly in the hole of the work piece to cut the material and
produce threads.
Operations are carried out simultaneously on both sides. A continuous supply
of coolant is required in order to reduce the heat production and wash away
the chips.
CNC Station 4-Smooth Turning:
The roughly finished axle in the previous station is now given a good
surface finish by turning operation. A six edged carbide tool is fixed in the
the ends are drilled at the same time.
Reaming
Reaming is the operation of finishing a previously drilled hole to bring it to
an exact size and to improve the surface finish of the hole. The operation is
earned out using a multi tooth revolving tool caller Reamer, which consists of a
set of parallel straight or helical cutting edges along the length of the cylindrical
tool. This operation is carried out at a speed lower than drilling in order to obtain a
good surface finish.
Tapping
Tapping is the operation of producing internal threads in a previously
drilled hole by means of a tool called tap. The tap has threads cut on its periphery
and is hardened to improve its properties. The threads cut on the tap form the
replica of the threads to be produced in the work piece. To generate a specific
size thread in the work piece, a hole with diameter smaller than the size of the
tap is first drilled using twist drill. To perform the tapping operation, the tool is
held rigidly in the spindle and is rotated at a speed less than drilling operation. The
rotating tap is fed slowly in the hole of the work piece to cut the material and
produce threads.
Operations are carried out simultaneously on both sides. A continuous supply
of coolant is required in order to reduce the heat production and wash away
the chips.
CNC Station 4-Smooth Turning:
The roughly finished axle in the previous station is now given a good
surface finish by turning operation. A six edged carbide tool is fixed in the
tool holder and is fed against the rotating work piece. The feed given is
very less in order to obtain the perfect finish. The axle dimensions are
same as required dimensions, with tolerance of about 3-5 microns. These
operations give finishing to the body of axle, while the dust guard and the
journal are finished by the Grinding.
Station 5-Grinding:
The journal is the most important part of the axle since this bearing is seated
on it. Hence the journal is given a perfect finish. This is done by grinding. Here
Centre less Grinding is done. The shape of the grinding wheel is same as that of
the axles, dust guard and journals shape. Hence for different axles different
grinding wheel must be used. Two wheels are kept on both the ends to finish
both the sides of the axles. They operate one after the other. In operation the
work piece comes near to the wheel and gets fixed. Now the high speed
grinding wheel approaches the axle due to which very fine material layer is
removed from the work piece due to the action of abrasive particles fixed on
the grinding wheel. In the same manner the other side of the axle is also
finished.
very less in order to obtain the perfect finish. The axle dimensions are
same as required dimensions, with tolerance of about 3-5 microns. These
operations give finishing to the body of axle, while the dust guard and the
journal are finished by the Grinding.
Station 5-Grinding:
The journal is the most important part of the axle since this bearing is seated
on it. Hence the journal is given a perfect finish. This is done by grinding. Here
Centre less Grinding is done. The shape of the grinding wheel is same as that of
the axles, dust guard and journals shape. Hence for different axles different
grinding wheel must be used. Two wheels are kept on both the ends to finish
both the sides of the axles. They operate one after the other. In operation the
work piece comes near to the wheel and gets fixed. Now the high speed
grinding wheel approaches the axle due to which very fine material layer is
removed from the work piece due to the action of abrasive particles fixed on
the grinding wheel. In the same manner the other side of the axle is also
finished.
Ultra Sonic Testing for wheels and axles:
Principle: the velocity of Ultra Sonic Waves (high frequency sound waves)
varies in different medium.
In axle machine shop the Ultra Sonic Waves are made to pass through the
axle/wheel. The velocity of these waves varies in different metal medium. When
the waves are sent, if they come across metallic and non- metallic inclusions
the velocity varies which can be detected through a computer connected to
the ultra-sonic testing machine. While propagating, if the waves come in
contact with the cracks, they reflect without passing through them this
change in wave signal is detected on the computer. The ultra-sonic testing
is done twice in the axle machine Shop. First when axle comes out of
STATION 1. Here the waves are sent in horizontal direction from two end
surfaces so that internal vertical cracks can be detected. Here the axial cracks
are detected.
Second Ultra Sonic Test is done when the axle is out of smooth turning. Here the
waves are sent in vertical direction along the whole length so that internal
horizontal cracks can be detected. It is called Radial Ultrasonic Testing as the
radial cracks are detected.
Advantages
• Sensitive to both surface and subsurface discontinuities.
• Depth of penetration for flaw detection or measurement is
superior to other methods.
• Only single-sided access is needed when pulse-echo
technique is used.
• High accuracy in determining reflector position and
estimating size and shape.
• Detailed images can be produced with automated systems.
• Has other use such as thickness measurements.
Principle: the velocity of Ultra Sonic Waves (high frequency sound waves)
varies in different medium.
In axle machine shop the Ultra Sonic Waves are made to pass through the
axle/wheel. The velocity of these waves varies in different metal medium. When
the waves are sent, if they come across metallic and non- metallic inclusions
the velocity varies which can be detected through a computer connected to
the ultra-sonic testing machine. While propagating, if the waves come in
contact with the cracks, they reflect without passing through them this
change in wave signal is detected on the computer. The ultra-sonic testing
is done twice in the axle machine Shop. First when axle comes out of
STATION 1. Here the waves are sent in horizontal direction from two end
surfaces so that internal vertical cracks can be detected. Here the axial cracks
are detected.
Second Ultra Sonic Test is done when the axle is out of smooth turning. Here the
waves are sent in vertical direction along the whole length so that internal
horizontal cracks can be detected. It is called Radial Ultrasonic Testing as the
radial cracks are detected.
Advantages
• Sensitive to both surface and subsurface discontinuities.
• Depth of penetration for flaw detection or measurement is
superior to other methods.
• Only single-sided access is needed when pulse-echo
technique is used.
• High accuracy in determining reflector position and
estimating size and shape.
• Detailed images can be produced with automated systems.
• Has other use such as thickness measurements.
Magnetic Particle Testing for wheels and axles:
This test is done to a completely finished axle/wheels just before it enters
the assembly shop where assembling of wheel and axle takes place. This
test is mainly to detect surface cracks. In this test, magnetic particle
powder is mixed in oil and is poured on the body of the axle/wheel which
is held in place by the chucks. DC current is used and the axle/wheel acts
as a permanent magnet until the current flows through. Then Ultra Violet
rays are incident on the axle/wheel. If no surfaces Cracks are present then
UV rays are reflected back else green light is affected. The axle/wheel with
cracks are rejected or else sent to heat treatment depending up on the
size of the crack.
Advantages
• Rapid Flaw Detection: Ideal for quickly locating surface and sub-surface
flaws and discontinuities in ferromagnetic material like Iron, Nickel,
Cobalt, and related alloys.
• Highly Adaptable: Ideal for inspection of irregular parts.
• As Forged or As Welded: Less preparation of inspected material as
sullied surface area is less important than other NDT methods. Inspection
of material in "as is" condition saving cost of cleaning and preparation.
• Economical: Less expensive application than other NDT methods.
• Highly portable: magnetic particle testing can be performed almost
anywhere
This test is done to a completely finished axle/wheels just before it enters
the assembly shop where assembling of wheel and axle takes place. This
test is mainly to detect surface cracks. In this test, magnetic particle
powder is mixed in oil and is poured on the body of the axle/wheel which
is held in place by the chucks. DC current is used and the axle/wheel acts
as a permanent magnet until the current flows through. Then Ultra Violet
rays are incident on the axle/wheel. If no surfaces Cracks are present then
UV rays are reflected back else green light is affected. The axle/wheel with
cracks are rejected or else sent to heat treatment depending up on the
size of the crack.
Advantages
• Rapid Flaw Detection: Ideal for quickly locating surface and sub-surface
flaws and discontinuities in ferromagnetic material like Iron, Nickel,
Cobalt, and related alloys.
• Highly Adaptable: Ideal for inspection of irregular parts.
• As Forged or As Welded: Less preparation of inspected material as
sullied surface area is less important than other NDT methods. Inspection
of material in "as is" condition saving cost of cleaning and preparation.
• Economical: Less expensive application than other NDT methods.
• Highly portable: magnetic particle testing can be performed almost
anywhere
ASSEMBLY
SHOP
SHOP
Assembly
The assembly of wheel sets is done on a highly automated wheel assembly
complex. The wheel seat size of the axles is measured on an automated measuring
unit and the dimensions are transferred to two wheel borers. Paired wheels are
custom bored as per the wheel seat size to get correct interference fit. The wheels
are then pressed on axle in a 300 T Wheel press. In assembly shop, the wheel seat
diameter is sent to a Measuring Station where it is exactly measured to each axle
and wheel for the particular axle is centre bored to the measured axle’s wheel
seat diameter by the vertical boring machine using octagon shaped tool. After the
smooth surface finish boring operation the two wheels for one particular axle are
sent for pressing.
The two wheels are hydraulically pressed on a Mounting Press, so that the
two wheels sit on the wheel seat of the axle by using pressing machine one wheel
after the other. This combination of two wheels and an axle is called Wheel Set.
The pressure to be applied on the wheel for pressing each wheel varies on
different properties. Castor oil is applied on the axle during pressing in order to
reduce the pressure on the axle. The pressure applied is recorded in the form of a
graph. The wheel sets obtained is measure by various gauges (e.g. Offset gauge).
In case the distance between wheels is to be altered or any other minor
corrections need to be done is corrected by damping machine. Once the wheel set
is inspected, it is painted to prevent the surface of the axle from rusting and the
journal is covered and then transported to place where rest of the body parts of
the train is manufactured.
The assembly of wheel sets is done on a highly automated wheel assembly
complex. The wheel seat size of the axles is measured on an automated measuring
unit and the dimensions are transferred to two wheel borers. Paired wheels are
custom bored as per the wheel seat size to get correct interference fit. The wheels
are then pressed on axle in a 300 T Wheel press. In assembly shop, the wheel seat
diameter is sent to a Measuring Station where it is exactly measured to each axle
and wheel for the particular axle is centre bored to the measured axle’s wheel
seat diameter by the vertical boring machine using octagon shaped tool. After the
smooth surface finish boring operation the two wheels for one particular axle are
sent for pressing.
The two wheels are hydraulically pressed on a Mounting Press, so that the
two wheels sit on the wheel seat of the axle by using pressing machine one wheel
after the other. This combination of two wheels and an axle is called Wheel Set.
The pressure to be applied on the wheel for pressing each wheel varies on
different properties. Castor oil is applied on the axle during pressing in order to
reduce the pressure on the axle. The pressure applied is recorded in the form of a
graph. The wheel sets obtained is measure by various gauges (e.g. Offset gauge).
In case the distance between wheels is to be altered or any other minor
corrections need to be done is corrected by damping machine. Once the wheel set
is inspected, it is painted to prevent the surface of the axle from rusting and the
journal is covered and then transported to place where rest of the body parts of
the train is manufactured.
PROGRAMABLE LOGIC CONTROLLER’S.
A PLC is an industrial computer control system that continuously monitors
the state of input devices and makes decisions based upon a custom
program to control the state of output devices.
Almost any production line, machine function, or process can be greatly
enhanced using this type of control System. However, the biggest benefit
in using a PLC is the ability to change and replicate the operation or
process while collecting and communicating vital information. Another
advantage of a PLC system is that it is modular. That is, you can mix and
match the types of Input and Output devices to best suit your application.
What is Inside A PLC?
The Central Processing Unit, the CPU, contains an internal program that tells
the PLC how to perform the following functions:
A PLC is an industrial computer control system that continuously monitors
the state of input devices and makes decisions based upon a custom
program to control the state of output devices.
Almost any production line, machine function, or process can be greatly
enhanced using this type of control System. However, the biggest benefit
in using a PLC is the ability to change and replicate the operation or
process while collecting and communicating vital information. Another
advantage of a PLC system is that it is modular. That is, you can mix and
match the types of Input and Output devices to best suit your application.
What is Inside A PLC?
The Central Processing Unit, the CPU, contains an internal program that tells
the PLC how to perform the following functions:
Execute the Control Instructions contained in the User's Programs. This
program is stored in "nonvolatile" memory, meaning that the program
will not be lost if power is removed.
Communicate with other devices, which can include I/O Devices,
Programming Devices, Networks, and even other PLCs.
Perform Housekeeping activities such as Communications, Internal
How PLC works
Basics of a PLC function are continual scanning of a program. The scanning
process involves three basic steps.
Step 1: Testing input status
First the PLC checks each of its input with intention to see which one has status
on or off. In other words it checks whether a switch or a sensor etc., is
activated or not. The information that the processor thus obtains through this
step is stored in memory in order to be used in the following steps.
Step 2: Programming execution
Here a PLC executes a program instruction by instruction based on the
program and based on the status of the input has obtained in the preceding step,
and appropriate action is taken. The action might be activation of certain
outputs and the results can be put off and stored in memory to be retrieved later
in the following steps.
Step 3: Checking and Correction of output status
Finally, a PLC checks up output signals and adjust it has needed. Changes are
performed based on the input status that had been read during the first step
and based on the result of the program execution in step two – following
execution of step three PLC returns a beginning of the cycle and continually
repeats these steps.
program is stored in "nonvolatile" memory, meaning that the program
will not be lost if power is removed.
Communicate with other devices, which can include I/O Devices,
Programming Devices, Networks, and even other PLCs.
Perform Housekeeping activities such as Communications, Internal
How PLC works
Basics of a PLC function are continual scanning of a program. The scanning
process involves three basic steps.
Step 1: Testing input status
First the PLC checks each of its input with intention to see which one has status
on or off. In other words it checks whether a switch or a sensor etc., is
activated or not. The information that the processor thus obtains through this
step is stored in memory in order to be used in the following steps.
Step 2: Programming execution
Here a PLC executes a program instruction by instruction based on the
program and based on the status of the input has obtained in the preceding step,
and appropriate action is taken. The action might be activation of certain
outputs and the results can be put off and stored in memory to be retrieved later
in the following steps.
Step 3: Checking and Correction of output status
Finally, a PLC checks up output signals and adjust it has needed. Changes are
performed based on the input status that had been read during the first step
and based on the result of the program execution in step two – following
execution of step three PLC returns a beginning of the cycle and continually
repeats these steps.
PLC Advantages and Disadvantages
Flexibility: One single Programmable Logic Controller can easily run many
machines.
Correcting Errors: In old days, with wired relay-type panels, any program
alterations required time for rewiring of panels and devices. With PLC
control any change in circuit design or sequence is as simple as retyping the
logic. Correcting errors in PLC is extremely short and cost effective.
Low Cost: Prices of Programmable Logic Controllers vary from few
hundreds to few thousands. This is nothing compared to the prices of the
contact and coils and timers that you would pay to match the same things.
Add to that the installation cost, the shipping cost and so on.
Testing: A Programmable Logic Control program can be tested and
evaluated in a lab. The program can be tested, validated and corrected
saving very valuable time.
Visual observation: When running a PLC program a visual operation can be
seen on the screen. Hence troubleshooting a circuit is really quick, easy and
simple.
Flexibility: One single Programmable Logic Controller can easily run many
machines.
Correcting Errors: In old days, with wired relay-type panels, any program
alterations required time for rewiring of panels and devices. With PLC
control any change in circuit design or sequence is as simple as retyping the
logic. Correcting errors in PLC is extremely short and cost effective.
Low Cost: Prices of Programmable Logic Controllers vary from few
hundreds to few thousands. This is nothing compared to the prices of the
contact and coils and timers that you would pay to match the same things.
Add to that the installation cost, the shipping cost and so on.
Testing: A Programmable Logic Control program can be tested and
evaluated in a lab. The program can be tested, validated and corrected
saving very valuable time.
Visual observation: When running a PLC program a visual operation can be
seen on the screen. Hence troubleshooting a circuit is really quick, easy and
simple.
Bibilography
RWF Website www.rwf.indianrailways.gov.in
www.spacersandwashers.com
https://www.wikipedia.org/
https://www.elsevier.com/journals/title/a
RWF Website www.rwf.indianrailways.gov.in
www.spacersandwashers.com
https://www.wikipedia.org/
https://www.elsevier.com/journals/title/a
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