Non-Traditional Machining Processes

Introduction: [1]

Traditional machining processes: [1] [2]

Traditional machining processes are defined as a group of processes in which desired shape,
size and surface finish are obtained by removing excess material in form of chips with the
help of comparatively harder wedge shaped device known as cutting tool by utilising
mechanical energy only.

Traditional, also termed conventional, machining requires the following: [1]

 In order to obtain desired shape, size and surface finish of the work piece, excess
material is removed in form of chips.
 There should have a wedge shaped device known as cutting tool which is harder
than the work piece to be machined.

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 This tool should be penetrated in the work piece to a certain depth.

 Moreover, a relative motion between the tool and work piece is responsible for
forming or generating the required shape.
The absence of any of these elements in any machining process such as the absence of tool-
work piece contact or relative motion makes the process a non-traditional one.

Non-traditional machining processes: [1] [2]

Non-traditional machining processes are defined as a group of processes in which desired
shape, size and surface finish are obtained by removing excess material with the help of
various techniques involving mechanical, thermal, electrical or chemical energy or
combinations of these energies but do not use a sharp cutting tools as it needs to be used
for traditional machining processes.

Classification of non-traditional machining processes: [3]

Sl. Mechanics of
Energy Type Energy source Process
No. material removal
Mechanical motion Conventional
01 Plastic shear
of tool / job machining
Abrasive jet machining
02 Mechanical
Mechanical / fluid (AJM)
Erosion
motion Ultrasonic machining
03
(USM)
Electrochemical
04 Electrochemical Ion displacement Electric current
machining (ECM)
Mechanical and Plastic shear and Electric current and Electrochemical
05
electrochemical ion displacement mechanical motion grinding (ECG)
Corrosive Chemical machining
06 Chemical Corrosive agent
reaction (CHM)
Electric discharge
07 Electric spark
machining (EDM)
High speed Electron beam
08
electrons machining (EBM)
Fusion and Laser beam machining
09 Thermal Powerful radiation
vaporization (LBM)
Ion beam machining
10
(IBM)
Ionized substance
Plasma arc machining
11
(PAM)
Table: Traditional and non-traditional machining process [3]

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Reasons for using Non-traditional Machining (NTM) Processes: [4][5]

Now a day for the value addition to the raw material the conventional machining process is not up to
mark in different aspects such as accuracy, repeatability, surface finish, tolerance etc. Another thing is
the working with very hard material is not possible by conventional process. There are such more
reasons for which there is need of the Non-Traditional Manufacturing Processes.
 Very hard material can be machined easily.
 The accuracy and surface finish are very high.
 Complex surfaces in three dimensions can be produced.
 Intricate shaped blind hole can be made.
 Deep hole with very small hole diameter.
 NTM is generally automatic machining processes.
 Very small amount material removal at atomic level is possible.
 Surface produced are of good quality.
 Generally, no need of subsequent finishing operation.

Advantages of Non-traditional Machining (NTM) Processes: [2]

 Complex geometries beyond simple planar or cylindrical features can be machined.
 Parts with extreme surface-finish and tight tolerance requirements can be obtained.
 Delicate components that cannot withstand large cutting forces can be machined.
 Parts can be machined without producing burrs or inducing residual stresses.
 Brittle materials or materials with very high hardness can be easily machined.
 Microelectronic or integrated circuits can be mass-produced.

Limitations of Non-traditional Machining (NTM) Processes: [2]

 Individual non-traditional machining processes having specific applications and
limitations, any non-traditional machining process cannot be used universally for any
kind of machining operation.
 In non-traditional machining processes the specific energy consumption (ie. energy
consumption per unit volume material removal per unit time) is generally much
higher than that of traditional machining processes.
 The cost of installation and maintenance of the equipments related to non-
traditional machining are high enough.
 Highly skilled and knowledgeable operators are required to operate such
equipments.

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Comparison of non-traditional and traditional machining process: [1] [2] [3] [4]
Sl. No. Non-traditional machining processes Traditional machining processes
Processes involving mechanical, Generally processes involving
01 thermal, electrical or chemical energy mechanical energy only.
or combinations of these.
In most of the processes, In all processes, conventional chip
02 conventional chip formation does not formation takes place during material
take place during material removal. removal.
In most of the processes, there is no In all processes, there is physical contact
03 physical contact between tool and between tool and work piece during
work piece during material removal. material removal.
Tool material may or may not be Tool material must be harder than work
04
harder than work piece material. piece material.
Complex surfaces with difficult Machining of complex surfaces with
05 geometry can be machined easily. difficult geometry is really difficult, in
many cases it become impossible.
Parts with extreme surface-finish and Machining of Parts with extreme
tight tolerance can be obtained easily. surface-finish and tight tolerance is
06
really difficult, in many cases it become
impossible.
Brittle materials or materials with Machining of such material is really
07 very high hardness can be easily difficult, in many cases it become
machined. impossible.
Delicate components that cannot Machining of such material is
08 withstand large cutting forces can be impossible.
machined.
Parts can be machined without Machining products without producing
producing burrs or inducing residual burrs is very difficult and inducing
09
stresses. residual stresses is an evident limitation
of traditional machining processes.
Micromachining is possible in such Micromachining is not possible in such
10
processes. processes.
Specific energy consumption is high. Specific energy consumption is
11
comparatively low.
The cost of installation and The cost of installation and
maintenance of the equipments maintenance of the equipments related
12
related to non-traditional machining to traditional machining are
are high enough. comparatively low.
Highly skilled and knowledgeable Comparatively less skilled operators
13 operators are required to operate may operate such equipments.
such equipments.

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Reference:
1. Advanced Machining Processes, Non-traditional and Hybrid Machining Processes,
by Hassan El-Hofy, Production Engineering Department, Alexandria University,
Egypt, published by McGraw-Hill, ISBN: 0-07-145334-2.
2. DeGarmo’s Materials and Processes in Manufacturing (Eleventh Edition), by J T.
Black, Auburn University-Emeritus and Ronald A. Kohser, Missouri University of
Science & Technology, published by John Wiley & Sons, Inc. ISBN-13 978-0-470-
92467-9.
3. Manufacturing Science (Second Edition), by Amitabha Ghosh, formerly Professor of
Mechanical Engineering, IIT, Kanpur and Asok Kumar Mallik, formerly Professor of
Mechanical Engineering, IIT, Kanpur, published by East-West Press Private Limited,
New Delhi, ISBN: 978-81-7671-063-3.
4. Manufacturing Technology, Metal Cutting and Machine Tools (Volume: 2), Third
Edition, by P. N. Rao, Professor, Department of Technology, University of Northern
Lowa, Cedar Falls, USA, published by McGraw-Hill, ISBN(13): 978-1-25-902956-1,
ISBN(10): 1-25-902956-5.
5. Non-conventional machining, Module: 9, Version: 2 ME by IIT Kharagpur.
https://nptel.ac.in/content/storage2/courses/112105127/pdf/LM-35.pdf.

MCQs on introduction of NTM:

1. Different classifications of Non-traditional machining based on source of energy are _______.
a) Mechanical
b) Thermal
c) Chemical and electro-chemical
d) All of the mentioned
2. Non-Traditional machining can also be called as ________.
a) Contact Machining
b) Non-contact machining
c) Partial contact machining
d) Half contact machining
3. Which of the following is a non-traditional process of machining?
a) Milling
b) EDM
c) Drilling
d) None of the mentioned
4. Surface defects that may be occurred during thermal machining are ________.
a) Micro cracking
b) Heat affected zones
c) Thermal distortion
d) All of the mentioned
5. Which of the following non-traditional process comes under mechanical machining?
a) USM
b) EDM
c) LBM
d) PAM

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6. In chemical machining is material removal takes by?

a) Chemical reaction
b) Erosion
c) Electron migration
d) None of the mentioned
7. The mechanics of material removal in traditional machining is __________.
a) Erosion
b) Plastic shear
c) Ion displacement
d) Fusion and vaporization
8. Which of the following is comes under traditional machining?
a) Electrochemical grinding
b) Grinding
c) Electric discharge machining
d) Chemical machining
9. In traditional machining, which component is made of relatively harder material?
a) Tool
b) Work piece
c) Holding device
d) None of the mentioned
10. Which of the following process comes under thermal machining?
a) USM
b) EDM
c) LBM
d) ECM

Frequently asked questions on introduction of NTM:

1. What is traditional and non-traditional machining?
2. Why non-traditional machining is required?
3. State the classification of non-traditional machining processes.
4. State the comparison among traditional and non-traditional machining processes.
5. State the advantages and disadvantages of non-traditional machining processes.

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