UNIT-I-METAL CASTING PROCESSES -Manufact

Manufacturing is the process of converting raw materials into finished goods through various production methods. Historically, manufacturing occurred on a small scale through apprenticeships or putting-out systems, but the Industrial Revolution led to large-scale manufacturing using machines powered by steam engines

1. 20ME303-MANUFACTURING
PROCESS-I
Mr.C.DINESHBABU,M.E.,(Ph.D).,
AP/MECH,
KNCET.

3. What is “Manufacturing”?
❑“the process of converting Raw materials
into products.”
❑The word “manufacturing” is delivered from
the Latin manu factus, meaning made by
hand.
❑“the conversion of stuff into things” – (by
DeGramon, 1998)
❑“economic terms for making goods and
services available to satisfy customer” – (by
T. Black, 1991)

4. Types of Manufacturing
Manufacturing can be defined two ways:
▪Technology – This process to accomplish
manufacturing involve a combination of
machinery, tools, power and manual labor.
Manufacturing also includes the assembly of
multiple parts to make products.

7. SAND CASTING
Casting is one of the Processes used for making
components of complicated shapes in large quantity. It is
process of producing metal parts by pouring molten metal
into the mould cavity of the required shape and allowing the
metal to solidify.
SAND MOULDS
Mould is the cavity of the required shape made in
moulding sand or in other material
PATTERN
It is model of the required casting made in wood,
metal, plastics.

9. TYPES OF PATTERN
Solid Split Pattern
Loose Piece Pattern Match Plate

10. TYPES OF PATTERN
Sweep Pattern Skeleton Pattern
Segmental Pattern Shell Pattern

11. PATTERN MATERIALS
The following factors are to be considered for the selection of
pattern materials
•Design of casting
•Number of castings to be produced
•Degree of accuracy and surface finish required
•Shape, complexity and size of the castings
•Casting or moulding method adopted

12. PATTERN MATERIALS
1.0 WOOD
• Teak wood, white pine, rose wood are used.
• Metal spray coating upto 0.25mm thick, coating materials Zinc and
Aluminium to avoid moisture absorption and good surface finish

13. PATTERN MATERIALS
2.0 METAL
• Mostly used when larger number of castings.
• Cast iron, Brass, Aluminium are used.

14. PATTERN MATERIALS
3.0 PLASTER
• Plaster of paris or gypsum cement is used
• Plaster can be easily made into difficult shapes and easily
worked.
4.0 PLASTICS
• Plastics pattern is cast from a wooden pattern called master
pattern.
• Light weight but strong and not affected by moisture and
more resistant to wear.
•Poly acrylates, Poly ethylene, Poly Vinyle chloride etc.
•
5.0 WAX
It is used in investment castings. Paraffin wax, shellac wax
•It has good surface finish and high dimensional accuracy
•It is used for making small pattern only

15. PATTERN ALLOWANCES:
Patterns are not made into exact size of the castings to be
produced.
Patterns are made slightly larger than the required casting.
This extra size given on the pattern is called pattern
allowances.
Types of pattern allowances:
1. Shrinkage allowance
2. Machining or finish allowance
3. Draft or Taper allowance
4.Distortion or chamber allowance
5. Rapping or shake allowance

16. PATTERN ALLOWANCES
1.Shrinkage allowance
• The extra size provided on the pattern for metal shrinkage
is called shrinkage allowance.
2. Machining or Finish allowance
• The pattern is made larger than the required casting for
finishing purpose.
•This extra size given to the pattern for machining purpose is
called machining or finish allowance.

17. PATTERN ALLOWANCES
3.0 Draft or Taper allowance
4.0 Rapping or Shake allowance

18. PATTERN ALLOWANCES
5.0 Distortion or Camber allowance

19. TYPES OF MOULDING SAND
1.Green sand
• Moist state is known as green sand.
• 5 to 8% of water and 16 to 30 % of clay.
• soft, light and porous.
2.Dry Sand
• Prepared in dry stage.
• Used for large casting
• Mould does not cause defects which causes due to
moisture.
3.Facing Sand
• Used directly cover the surface of the pattern and
comes contact with molten metal.
• It contains Silica, Clay, Talc, Graphite etc..

20. TYPES OF MOULDING SAND
4.Loam Sand
• It consists of fine silica sand, fine refractories, clay,
graphite, fibre and water
• It used for bell, roller, pulley etc.
5.Backing sand
• It used for backup the facing sand and to fill the
whole volume of the mould box.
6.Parting sand
• It used when a casting is made up of two halves
with cope and drag. It is sprinkled over the pattern to
avoid sticking of green sand.

21. PROPERTIES OF MOULDING SAND
1. Porosity or Permeability
• It is a measure of moulding sand by which the sand
allows the steam and gases to pass through it,
otherwise casting defects such as blowholes will
occur.
• It depends on Quality and quantity of clays,
Moisture, Degree of compactness.
2. Plasticity or flowability:
•It should flows around and over the pattern,
uniformly fills the flask.
3. Adhesiveness
• It sticks or adheres to moulding boxes. It does not
fall out when the flasks are lifted and turned over.

22. PROPERTIES OF MOULDING
SAND
4.Strength or cohesiveness
• It should have sufficient strength so that the mould
does not collapse during lifting, shifting, turning,
pouring the molten metal.
5.Refractoriness
• It should resist high temperature of molten metal
and depends on purity of the sand, sizes.
6.Collapsibility
• It should collapse easily after the casting solidifies.

23. TESTING OF MOULDING SAND
•Moisture content test
•Clay content test
•Grain fineness test
•Permeability test
•Strength test
•Deformation and toughness test
•Hot strength test
•Refractoriness test
•Mould hardness test

24. TESTING OF MOULDING SAND
1.0 Moisture content test
a) Loss of weight after evaporation
20 to 50grms
Constant Temperature 100˚ /1 hour
Moisture content = W1 – W2
% of moisture content = (W1 – W2) x 100
W1

W1 – weight of sand before drying
W2 – after drying

25. b) Moisture teller method
•Water and Calcium carbide react the form
Acetylene gas which can be measured and this will
be proportional to moisture content.
•Pressure gauge to read directly the % of moisture
present in the Moulding sand.

26. TESTING OF MOULDING SAND
2.0 Clay content test
•Clay in moulding sand 50grams as particles
which is suspended in water, fail to settle the
rate of 1 inch/min.
•Clay consists ≤ 20micron/0.0008 inch in dia.
Clay content = W1 – W2,
W1 – weight of sand before drying,
W2 – after drying.
% of clay content = (W1 – W2)/W1 x 100

27. TESTING OF MOULDING SAND

3.0 Grain fineness test (MECHANICAL SHAKER)
•STANDARD MESHES MOUNTED BY MECHANICAL
SHAKER
6,12,20,30,40,50,70,100,140,200,270
•Series order from top to bottom.

28. TESTING OF MOULDING SAND
4.0 Strength test
Measure of holding power or bonding power.
Unit –kgf/cm2
a)Compressive strength
b)Shear strength
c)Tensile strength
d)Bending strength

29. TESTING OF MOULDING SAND
5.0 Permeability test
Tendency of sand which allows the escape of gases or air through it.
P=(2000×5.08)/(10×20.268×(1/6)=300.66
Permeability number = VH / APT
V = Volume of air (2000cc)
H = Height of the specimen = 5.08mm
A = Area of specimen = πd
2
/4 =20.268cm
2
T = Time taken by 2000cc
P = Pressure measured in manometer.

30. CORES
•A core is a body made of refractory material, which is
used for making cavity or a hole in casting.
•It’s shape is similar to the required cavity in the casting.
•Core Print is a projection provided on the casting
product. It forms a seat in the mould.

31. Core Making Materials
A core is made of core sand, binder and
additives
•Core sand consists of refractories such as
silica sand, zircon, olivine etc
•Binders contains of vegetable oil or mineral
oil, core flour, resins water, fire clay, urea.
•Additives are wood flour, coal powder,
graphite, cow dung.

32. CORE TYPES AND APPLICATIONS
•1.Core blowing machines:
•Basic principle is comprises of filling the core
sand into the core box by using compressed air.
•CLASSIFIED IN TO TWO TYPES:
•Small Bench Blowers:
•The cartridge is filled using hands.
•Core box and Cartridge are placed in the machine
for blowing, Right handle of the machine clamps the
box and the Left handle blows the core.
•Quite economical for core making shops having low
production.

33. CORE TYPES AND APPLICATIONS
•Large floor blowers:
•Floor model blowers possess stationary sand
magazine and automatic control.
•Main advantage being more automation oriented.
2.Core ramming machines
•Ramming core sands in the core boxes by machines
based on the principles of
(a)Squeezing
(b)Jolting
(c).Slinging

34. CORE TYPES AND APPLICATIONS
3. Core drawing machines:
•Core boxes have deep draws.
•After ramming sand in it, the core box is placed on
a core plate supported on the machine.
4.Core baking
•The main purpose of baking is to drive away the
moisture and harden the binder, thereby giving
strength to the core.

35. CORE TYPES AND APPLICATIONS
5. Continuous type ovens:
Mostly preferred for mass production.
Core carrying conveyors or chain move continuously
through the oven.
The continuous type ovens are generally used for
baking of small cores.

36. MOULDING MACHINES
•Moulding machines is used for mass production.
•Since the hand moulding is a slow process, only
making few casting.
•For more castings, Moulding is done by using
moulding machines.
a)Jolting Machine
•Raised about 80mm and suddenly dropped.
•The table will be operated pneumatically or
hydraulically
•The sudden dropping of table from a height makes
the sand pack evenly around the pattern.

37. Jolting Machine
•Mainly used for ramming horizontal surfaces on
the mould.
•Operation is noisy because of jolting.

38. Squeezing Machine
• The mould sand in the flask is squeezed between the
machine table and squeezer head.
•The mould board is clamped on the table. The flask
is placed on the mould board

39. Squeezing Machine
•The pattern is placed inside the flask. The sand is
filled up and leveled.
•The table is raised by the table lift mechanism against
the squeezer head.
•The pattern enters the sand frame and packs the
sand tightly.
•After squeezing the flask, the table comes down to the
starting position.

40. Sand Slinger
•The slinger has an impeller which can be
rotated with different speeds
•Impeller rotates, it throws a stream of sand at
greater velocity into the flask

41. Sand Slinger
•The slinger can be moved to pack the sand uniformly
around the pattern.
•The density of sand is controlled by the speed of
the impeller.
•The ramming will be uniform with good strength.
• It is used for large and medium size moulds.

42. MELTING FURNACES
1.0 CUPOLA FURNACE

44. L,

45. BLAST FURNACE
• Furnace used for melting metal ore, usually
iron ore.
•The combustion material and ore are supplied
from the top while air flow.
•supplied from the bottom of the chamber so
that the chemical reaction takes place.
•Used for melting iron to produce pig iron
which is the raw material for wrought
and cast iron.

46. BLAST FURNACE
•Very high temperature is developed inside the
furnace by forcing a blast of heated air.
• Its height is about 30 m and interior
diameter is of 8 m.
•The nature of reaction takes place inside the
furnace
Fe2O3 +3CO → 2Fe + 3C02
CaCO3 →CaO + CO2
•The largest blast furnaces produce around
60,000 tonnes of the iron per week.

47. c. Induction Furnace

48. Induction Furnace
•It consists of a refractory crucible which is
placed in an induction furnace and
centrally located on the refractory lining at
the bottom of shell.
•The crucible is surrounded by water- cooled
copper coil tubing.
•Insulation is provided between coil and
crucible.
•The furnace is mounted on two pedestals.
• It is used to tilt the furnace for pouring
the molten metal.

49. Induction Furnace
Advantages:
1. It gives excellent uniformity of the melt
composition.
2. There is no need of electrodes and simple
construction.
Applications:
• It is used to melt alloy tool steels and low
carbon alloys in small quantity.

50. SPECIAL CASTING PROCESSES
1.0 SHELL MOULD CASTING

51. SHELL MOULD CASTING
Advantages:
•1. A high accuracy castings with tolerances of +0.002 to
0.005 mm/mm is possible.
•2. Good surface finish can be obtained.
•3.Complex parts can be made by this method.
Applications:
•1. It is used for making brake drums and bushings.
•2. Cams, cam shaft, piston and piston rings can be
made.
• 3. It is used for making small pulleys, motor housing,
fan blades etc.
•4. Air compressor reservoir and cylinders,
crankcases, conveyor, rollers etc., can

52. 2.0 INVESTMENT CASTING

53. INVESTMENT CASTING
Advantages:
1. Complex shapes can be cast accurately.
2. Surface finish is very good.
3. High accuracy can be maintained.
4.Number of casting can be made at a time.
Applications:
1.Production of nozzles, buckets, vanes and blades for
gas turbine.
2.Making parts for aerospace industry such as
aircraft engines, frames and fuel
3.This process is applied in costume jewellery.

54. 4.0 PRESSURE DIE CASTING
a. HOT CHAMBER DIE CASTING

55. b. COLD CHAMBER DIE CASTING

56. •Advantages:
1. Very accurate castings of can be produced with the
dimensional tolerance range of + 0.03 to 0.25 mm.
2. Castings with very good surface finish can be made.
3. Rate of production (700 castings per hour) is high.
4. There is no possibility of sand inclusions.
•APPLICATIONS:
1. Household equipment such as washing machine parts, vacuum
cleaner body, fan case, store parts etc.
2. Automobile parts such as fuel pump, carburetor body, horn,
wiper and crank case.
3. Components for telephones, television sets, speakers,
microphones, record players and so on
4. Toys, such as pistols, electric trains, model aircraft's etc.

57. 5.0 CENTRIFUGAL CASTING

58. CO
2 PROCESS

59. 7.0 CO
2 PROCESS
• Pure dry silica sand mixed with sodium silicate liquid use
as a binder for making core.
• NaSiO3 + CO2----------- NaCO3 + SiO2
• Moisture should not exceed 3%.
• CO
2 gas is passed through the core for 30 sec at a pressure
of 140 KN/m
2
.
• CO
2 react with sodium silicate and forms sodium
carbonate and silica gell.
• Silica gell binds the sand grains together to provide
strength and hardness to the core.

60. DEFECTS IN CASTINGS