Non Traditional Machining

Some past engineering industries have witnessed a rapid growth in the development of harder and difficult to machine material such as Hastelloy, Nitralloy, Waspalloy, Nimonics, stainless steel and much other high strength temperature resisting alloys.

This material widely used in various industries like aerospace, nuclear engineering and other industries. for such materials the conventional edged tool machining, in spite of recent technological advancement, is highly uneconomical and the degree of accuracy and surface finish are poor. and machining of these materials are complex shapes is difficult and sometimes impossible.

In 1960 merchant emphasized the need for the development of newer concepts in metal machining these processes are non-conventional or unconventional in the sense that they do not employ a conventional tool for metal removal. they directly utilize some form of energy for metal machining.  

Classification of non-conventional machining process :

They are classified in the various groups according to the type of fundamental machining they employ named mechanical, electrical, chemical, electro-chemical, thermo-electric etc.

They are classified according to energy used, the mechanism of metal removal in the process and the medium for transfer of those energies etc.

Type of energy	The basic mechanism of metal removal	Transfer media	Energy source	Process
Mechanical	Erosion shear	High velocity particles, physical contact	Pneumatic/hydraulic pressure cutting tool	AJM USM Conventional machining
Chemical	Chemical ablation	Reactive environment	Corrosive agent	CHM
Electro-chemical	Ion displacement	Electrolyte	High current	ECM ECG
Thermo-electric	Fusion vaporization	Hot gases electron radiation	Ionized material high voltage amplified light	IBM PAM EBM EDM LBM

  Mechanical :

• Abrasive Jet Machining ( AJM )
• Ultrasonic Machining ( USM )

Chemical :

• Chemical Machining ( CHM )

 Electro-Chemical :

• Electro-Chemical Machining ( ECM )
• Electro-Chemical Grinding ( ECG )

Thermo-electric : 

• Ion-Beam Machining ( IBM )
• Plasma Arc Machining ( PAM )
• Electrical Discharge Machining ( EDM )
• Electron-Beam Machining ( EBM )
• Laser-Beam Machining ( LBM )

Process Selection :

The points which should be looked before the selection of these process are as below : 

1. Physical parameters.
2. Properties of the work material and shape to be machined.
3. Process capability or machining characteristics.
4. Economic survey. 

Materials application of the various methods are given in the table below :
  

Process	Aluminium	Steel	Super alloy	Titanium	Refractories	Ceramics	Plastic	Glass
USM	G	F	P	F	G	G	F	G
AJM	F	F	G	F	G	G	F	G
ECM	F	G	G	F	F	N	N	N
CHM	G	G	F	F	P	P	P	F
EDM	F	G	G	G	G	N	N	N
EBM	F	F	F	F	G	G	F	F
LBM	F	F	F	F	P	G	F	F
PAM	G	G	G	F	P	N	P	N

Where

G = Good

F = Fair

P = Poor

N = Not applicable

The processing capability or machining characteristics can be analyzed with respect to :

1. Metal removal rate obtained.
2. Tolerance maintained.
3. The surface finish obtained.
4. Depth of surface damage.
5. Power requires machining.

The economics of the various process is analyzed by considering :

1. Capital cost.
2. Tooling cost.
3. Consumed power cost.
4. Metal removal rate efficiency.
5. Wear of tooling.