Basics of Mechanical Engineering (BCME)- Unit-2.pdf

Suitable for JNTU- K, H Engineering graduates who gets quick introduction about Mechanical engineering subject

1. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)


UNIT II
Manufacturing Processes: Principles of Casting, Forming, joining processes, Machining,
Introduction to CNC machines, 3D printing, and Smart manufacturing.
Thermal Engineering – Working principle of Boilers, Otto cycle, Diesel cycle, Refrigeration
and air-conditioning cycles, IC engines, 2-Stroke and 4-Stroke engines, SI/CI Engines,
Components of Electric and Hybrid Vehicles.

Casting is a process in which a material such as metal or plastic in liquid form is poured into a mold and
allowed to become hard, in order to make parts or products. Casting is the most efficient way of making
complex metal shapes.


STEPS IN CASTING

2. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

3. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)




Advantages of Sand
casting
Disadvantages of Sand
casting
Simple production process Handmade process
Low cost Casting molds Low strength
Lower production costs Low dimensional accuracy
Wider material choice Rough surface quality
High complexity shapes More casting defects
Short lead time Unstable casting quality

4. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)






Casting properties
 Fluidity.
 Shrinkage. Shrinkage cavity. Shrinkage porosity.
 Surface quality.
 Resistance to cracks formation.





FORMING PROCESS
In metalworking, forming is the fashioning of metal parts and objects through
mechanical deformation; the workpiece is reshaped without adding or removing
material, and its mass remains unchanged.

 The two main types of metal forming are bulk forming and sheet forming. Forming
operates on the materials science principle of plastic deformation, where the
physical shape of a material is permanently deformed.
 Forming is also classified as cold forming, hot forming or warm forming. Hot
forming is the deformation carried out at temperatures above recrystallization
temperatures.

5. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)








The important property of a material in metal forming processes is
 elasticity. plasticity. ductility. brittleness.
Among the most commonly used metals are aluminum, steel, and brass, but also
copper, tin, lead, magnesium, zinc, and titanium. The selection of material for forming
depends on the method. Depending on the properties of the metal, it will be more or
less easily processed.

6. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)



JOINING PROCESS
Joining processes are characterized by their ability to fuse or “join” two or more
components for the purpose of creating a different object, such as a ready-to-sell
consumer product.
Welding is a process that uses "heat" and "electricity" to connect two pieces of metal, and the
type of welding metal will also affect the welding results and technical requirements; like
many professional skills, welding technology also has different levels of difficulty. First
understand the most common types of welding introduction, principle teaching, and skill
analysis.

7. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

8. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)



Soldering is a process used for joining metal parts to form a mechanical or
electrical bond. It typically uses a low melting point metal alloy (solder) which is
melted and applied to the metal parts to be joined and this bonds to the metal
parts and forms a connection when the solder solidifies.

Brazing, process for joining two pieces of metal that involves the application of
heat and the addition of a filler metal. This filler metal, which has a lower melting
point than the metals to be joined, is either pre-placed or fed into the joint as the
parts are heated.

Adhesive bonding is a process in which joining between two or more parts is
accomplished by the solidification or hardening of a non-metallic adhesive
material, placed between the faying surfaces of the parts.

The 5 Types of Adhesive Bonding Materials
 EPOXY. Generally, epoxies are hard and durable adhesives that successfully bond
many substrates. ...
 GLUE. ...
 SPRAY ADHESIVE. ...
 ADHESIVE FILM. ...
 ADHESIVE TAPE.


MACHINING PROCESS

The metal fabrication method called machining refers to the process of shaping metal by removing the
unwanted material from it. This process can be performed in a variety of ways. Many machining processes
exist, including drilling, turning, and milling.

9. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)





Introduction to CNC machines

Computer numerical control (CNC) is a manufacturing method that automates the
control, movement and precision of machine tools through the use of preprogrammed
computer software, which is embedded inside the tools. CNC is commonly used in
manufacturing for machining metal and plastic parts.
Components of a CNC system
 Central processing unit (CPU)
 Input devices.
 Machine control panel.
 Programmable logic controller (PLC)
 Servo-control unit.
 Display unit.

10. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)


 CNC Machining Can Be Repeated. The best benefit of CNC punching is that
once you set the design, you can make as many copies of it as your materials
will allow. ...
 Dental Equipment. ...
 Weapons. ...
 Construction. ...
 Transportation. ...
 Research And Development. ...
Five Types of CNC Machines
 CNC Milling Machine. As one of the most popular CNC machines, CNC mills
are primarily used for milling, drilling, and cutting operations. ...
 CNC Plasma Cutters. ...
 CNC Lathe Machines. ...
 CNC Laser Cutting Machines. ...
 CNC Drilling Machine.
M code is the machine control language that controls the overall program, often called
G code. While G(geometric code) commands describe positions, M(miscellaneous) code
directs the machine's actions.

11. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

12. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)



3D printing

3D printing, also known as additive manufacturing, is a method of creating a three dimensional object layer-by-
layer using a computer created design. 3D printing is an additive process whereby layers of material are built
up to create a 3D part.
3D printing is a process that uses computer-aided design, or CAD, to create objects layer by layer. 3D printing
is commonly used in manufacturing and automotive industries, where tools and parts are made using 3D
printers.

13. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

14. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)




Smart manufacturing

Smart manufacturing (SM) is a technology-driven approach that utilizes Internet-
connected machinery to monitor the production process. The goal of SM is to identify
opportunities for automating operations and use data analytics to improve manufacturing
performance.
All effective smart manufacturing platforms have four elements in common: data
integration, data analysis and visualization, adaptability and scalability, and good user
experience.
A smart factory can be created by reducing paper documents, aligning and integrating
IT solutions, planning in real-time, creating autonomous and interacting production areas
with a centralized data backbone.

15. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)





Thermal Engineering – Working principle of Boilers, Otto cycle, Diesel cycle, Refrigeration
and air-conditioning cycles, IC engines, 2-Stroke and 4-Stroke engines, SI/CI Engines,
Components of Electric and Hybrid Vehicles.

16. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)


Thermal engineering, a sub-category of mechanical engineering, is an important field
that studies the transfer of heat energy between two systems, transforming the heat
energy into another form of energy. Thermal engineers use their expertise in the
principles of thermodynamics to design heating and cooling systems.
The field teaches information in Fluid Mechanics, Thermodynamics, Heat transfer
and Mass Transfer, Refrigeration System Design, Power Plant, Steam Generators, CFD,
Solar Thermal Technology.
Applications
 Boiler design.
 Combustion engines.
 Cooling systems. Cooling of computer chips.
 Heat exchangers.
 HVAC.
 Process Fired Heaters.
 Refrigeration Systems.
 Compressed Air Systems.

Hot gases are produced by burning fuel in the furnace. These hot gases
are made to come in contact with the water vessel where the heat transfer
takes place between the water and the steam. Therefore, the basic principle
of the boiler is to convert water into steam by using heat energy.




A boiler is a closed vessel system that is typically used to produce hot water or steam.
There are basically two types of boilers available in the market, namely hot water
boilers and steam boilers. A hot water boiler is typically used to produce hot water for
domestic and commercial purposes, whereas the steam boiler is used to generate
steam. A steam boiler is usually used for industrial applications such as to generate the

17. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

driving force required for the movement of the wings of a motor or a turbine, to heat
or melt elements, etc. The combustion of fuels is generally used as the source of energy
to power the boilers. The advantages of using a boiler for various commercial and
domestic applications include high efficiency, low emission of toxic gases, even
distribution of heat, etc. Boilers can be used to perform various operations such as
cleaning, cooling, heating, sanitization, etc. Some of the boilers available in the market
are also used for humidification purposes and to generate power. A boiler serves to be
one of the most important and critical parts of a thermal power plant. Boilers are
generally used in railway engines, ships, power plants, hotels, offices, buildings,
greenhouses, and various other applications. Various factories and industries such as
food and beverage companies, pharmaceutical firms, textile plants, paper mills, metal
industries, sugar mills, etc. make use of boilers to carry out various operations. One of
the prime applications of boilers can also be seen in the health care and medicine
department. There are a variety of boilers are available in the market that can be
broadly categorized on the basis of the type of application, the portability requirement,
arrangement of the water circulation, position, output pressure value, and the type of
input fuel used.
Parts of boiler



The three main components of all boilers are the burner, combustion chamber and heat
exchanger.
 Burner. One of the most important parts of a boiler is the burner. ...
 Combustion Chamber. ...
 Heat exchanger. ...
 Aquastats. ...
 Backflow Valve. ...
 Circulator pumps. ...
 Controls. ...
 Deaerators/Condensers.

18. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)






IC engines, 2-Stroke and 4-Stroke engines, SI/CI Engines

An IC (Internal Combustion) engine is a heat engine that converts chemical energy
stored in the fuel into mechanical energy. It is used in vehicles, generators, and
various other applications. The working of an IC engine can be explained in the
following steps:
Intake stroke

19. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

The first stroke is called the intake stroke. In this stroke, the fuel-air mixture is drawn
into the engine cylinder through the open intake valve.
Compression stroke
The second stroke is called the compression stroke. In this stroke, the piston
compresses the fuel-air mixture inside the cylinder by moving upwards.
Power stroke
The third stroke is called the power stroke. In this stroke, the fuel-air mixture is ignited
by a spark plug or a high-pressure injector, causing an explosion that forces the piston
to move downward. This downward motion of the piston is the source of mechanical
energy.
Exhaust stroke
The fourth and final stroke is called the exhaust stroke. In this stroke, the exhaust
valve opens, and the piston moves upward, pushing the exhaust gases out of the engine
through the open exhaust valve.

20. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

21. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

22. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

23. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)





Otto cycle, Diesel cycle, Refrigeration and air-conditioning cycles

24. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)


The Otto cycle is a description of what happens to a gas as it is subjected to changes
of pressure, temperature, volume, addition of heat, and removal of heat. The gas that is
subjected to those changes is called the system(cylinder), It is the thermodynamic cycle
most commonly found in automobile engines.
The Otto Cycle, describes how heat engines turn gasoline into motion. Like
other thermodynamic cycles, this cycle turns chemical energy into thermal energy and
then into motion. The Otto cycle describes how internal combustion engines (that use
gasoline) work, like automobiles and lawn mowers.

The gas expands adiabatically as the piston moves from the top dead centre to the
bottom dead centre. Due to this expansion, the gas loses internal energy that is equal to
work. The volume changes with a ratio called the isentropic expansion ratio which is
equal to the compression ratio of Otto cycle.

Diesel cycle

In the Otto cycle, both intake and exhaust valves move up and down, while in the
Diesel cycle, only one valve moves up and one moves down. The Otto cycle and diesel
cycle are two main types of the cycle used for engines. Rudolf Diesel, 1913, German
thermal engineer who invented the internal-combustion engine that bears his name.
Diesel engines are also known as compression ignition piston engines. t is one of the
most frequent thermodynamic cycles that can be found in automotive engines. Diesel
engines are considered the direct applications of the diesel cycle.

25. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)




Refrigeration and air-conditioning cycles

Refrigeration, the process of removing heat from an enclosed space or from a
substance for the purpose of lowering the temperature. A refrigerator is a cyclic device,
which absorbs heat from a heat sink and reject heat to a heat source by consuming work.
The working fluid is called refrigerant, which usually undergoes phase changes in the
cycle.
Refrigeration is basic to the heating, ventilation and air conditioning industry. One of
the most important applications of refrigeration has been the preservation of perishable
food products, food processing, packaging, storing and transportation by storing them at
low temperatures.
Refrigerators work by causing the refrigerant circulating inside them to change from a
liquid into a gas. This process, called evaporation, cools the surrounding area and
produces the desired effect.
A refrigerant is a working fluid used in the refrigeration cycle of air conditioning
systems and heat pumps where in most cases they undergo a repeated phase transition
from a liquid to a gas and back again.

26. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)




The vapor-compression refrigeration is the most widely used cycle for refrigerators, air-
conditioners, and heat pumps.
The refrigeration cycle, sometimes called a heat pump cycle, is a means of routing heat
away from the area you want to cool. This is accomplished by manipulating the pressure
of the working refrigerant (air, water, synthetic refrigerants, etc.) through a cycle of
compression and expansion.
Merits
1. It helps to preserve food stuffs so that they maintain their natural, physical appearance
and nutritive value.
2. It has made possible the enjoyment of many foods throughout the year.
3. Daily shopping is no longer necessary. It saves steps, energy and time.
De-Merits
1. The advent of no frost or automatic de-frosting refrigerators and freezers have resulted
in a tendency to clean these less frequently. So it results in food spoilage.

27. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

2. If spills are not wiped up and foods not covered, their odours may be absorbed by
other foods in the compartment. As a result the original flavour may be altered.

AIR-CONDITIONING CYCLES

Air-conditioning is that process used to create and maintain certain temperature, relative
humidity and air purity conditions in indoor spaces. This process is typically applied to
maintain a level of personal comfort.
Air-conditioning is a system for controlling the temperature and humidity of air. If it gets
too hot, close the windows and turn on the air-conditioning. The vehicle's air-conditioning
system keeps the interior of the car cool in hot weather.
There are several types of air conditioners to choose from, including stand-alone
systems, like portable air conditioners or evaporative air conditioners, and split systems,
such as central air conditioners and ductless mini-split air conditioners, which have
components inside and outside the home.
All air conditioners use the same cycle of compression, condensation, expansion, and
evaporation in a closed circuit.

28. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)



APPLICATIONS
Air conditioning is required for
1. Providing thermal comfort to humans and other living beings – Comfort air
conditioning.
2. Providing conditions required for various products and processes in
industries – Industrial air conditioning.
3. Air conditioning systems for residences.
4. Commercial air conditioning system.
5. Air conditioning system for hospitals.
6. Laptop, mobile air conditioning systems.
Industrial air conditioning examples in 8 different industries
 Textile industries
 Printing industries
 Manufacturing of precision parts
 Semi-conductor industries
 Pharmaceutics
 Photographic materials
 Computer rooms
 Mines, power plants, etc.

Components of Electric and Hybrid Vehicles.

Electric Vehicle

An EV includes both a vehicle that can only be powered by an electric motor that draws
electricity from a battery (all-electric vehicle) and a vehicle that can be powered by an

29. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)

electric motor that draws electricity from a battery and by an internal combustion engine
(plug-in hybrid electric vehicle).
They employ 'fuel cell technology' to generate the electricity required to run the vehicle.
The chemical energy of the fuel is converted directly into electric energy.







HYBRID VEHICLES

A hybrid car uses more than one means of energy, combining a petrol or diesel engine
with an electric motor, and the two systems work with each other to move the vehicle.
This allows the car to burn less gasoline, achieving better fuel efficiency than a traditional
engine that solely uses fuel does.

30. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)


COMPONENTS OF HYBRID CARS

31. K Rajesh MTech (Mech), MTech (Cse), PGDE, PGDIPR (PhD)







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