INTRODUCTION:
Manufacturing
processes can be broadly divided into two groups and they are primary
manufacturing processes and secondary manufacturing processes. The former ones
provide basic shape and size to the material as per designer’s requirement. Casting,
forming, powder metallurgy are such processes to name a few. Secondary
manufacturing processes provide the final shape and size with tighter control
on dimension, surface characteristics etc. Material removal processes are
mainly the secondary manufacturing processes.
Material
removal processes once again can be divided into mainly two groups and they are
“Conventional Machining Processes” and “Non-Traditional Manufacturing
Processes”.
Examples
of conventional machining processes are turning, boring, milling, shaping,
broaching, slotting, grinding etc. Similarly, Abrasive Jet Machining (AJM),
Ultrasonic Machining (USM), Water Jet and Abrasive Water Jet Machining (WJM and
AWJM), Electro-discharge Machining (EDM) are some of the Non Traditional Machining
(NTM) Processes.
Conventional Machining VS.
Non-Conventional Machining:
Conventional machining usually involves
changing the shape of a work piece using an implement made of a harder
material. Using conventional methods to machine hard metals and alloys means
increased demand of time and energy and therefore increases in costs; in some
cases conventional machining may not be feasible.
Conventional machining also costs in
terms of tool wear and in loss of quality in the product owing to induced residual
stresses during manufacture. With ever increasing demand for manufactured goods
of hard alloys and metals, such as Inconel 718 or titanium, more interest has
gravitated to non-conventional machining methods.
Conventional machining can be defined as
a process using mechanical (motion) energy.
Non-conventional machining utilizes
other forms of energy.
The three main forms of energy used in
non-conventional machining processes are as follows:
• Thermal energy
• Chemical energy
• Electrical energy
Comparison
|
Conventional Manufacturing
Processes
1.
Generally
macroscopic chip formation by shear deformation.
2.
There
may be a physical tool present. for example a cutting tool in a Lathe
Machine,
3.
Cutting
tool is harder than work piece at room temperature as well as under machining
conditions
4.
Material
removal takes place due to application of cutting forces – energy domain can
be classified as mechanical
5.
Conventional
machining involves the direct contact of tool and work –piece
6.
Lower
accuracy and surface finish.
7.
Suitable
for every type of material economically
8.
Tool
life is less due to high surface contact and wear.
9.
Higher
waste of material due to high wear.
10.
Noisy
operation mostly cause sound pollutions
11.
Lower capital cost
12.
Easy
set-up of equipment.
13.
Skilled
or un-skilled operator may required
14.
Generally
they are manual to operate.
15.
They cannot
be used to produce prototype parts very efficiently and economically.
|
Non-Conventional Manufacturing
Processes
1.
Material
removal may occur with chip formation or even no chip formation may take
place. For example in AJM, chips are of microscopic size and in case of
Electrochemical machining material removal occurs due to electrochemical
dissolution at atomic level
2.
There
may not be a physical tool present. For example in laser jet machining,
machining is carried out by laser beam. However in Electrochemical Machining
there is a physical tool that is very much required for machining.
3.
There
may not be a physical tool present. For example in laser jet machining,
machining is carried out by laser beam. However in Electrochemical Machining
there is a physical tool that is very much required for machining.
4.
Mostly
NTM processes do not necessarily use mechanical energy to provide material
removal. They use different energy domains to provide machining. For example,
in USM, AJM, WJM mechanical energy is used to machine material, whereas in
ECM electrochemical dissolution constitutes material removal.
5.
Whereas
unconventional machining does not require the direct contact of tool and work
piece.
6.
Higher
accuracy and surface finish.
7.
Not
Suitable for every type of material economically
8.
Tool
life is more
9.
Lower
waste of material due to low or no wear.
10.
Quieter operation mostly no sound pollutions are produced.
11.
Higher capital cost
12.
Complex
set-up equipment.
13.
Skilled
operator required.
14.
Generally
they are fully automated process.
15.
Can be used
to produce prototype parts very efficiently And economically.
|
