1. Unconventional Machining Processes
14AU9132- Fast Track Course
Unconventional Machining Processes
Dr.Karthick Jayaram
Associate Professor, MCET

2. Introduction Manufacturing Technology I
Metal casting (Sand casting and other casting processes)
Bulk deformation (Metal Forming – Forging, Rolling, Extrusion)
Manufacturing of plastic materials (Injection molding, etc).
Manufacturing Technology II (Material removal process)
Metal Cutting or Mechanical Abrasion
Shaper, Planer, Slotter, Milling, Drilling, Broaching, Gear cutting, etc.
Grinding, Honing, Lapping, etc.
CNC and DNC

3. Introduction – Contd.
Machining – produces finished products with high degree of accuracy.
Conventional machining
Utilizes cutting tools (harder than workpiece material).
Needs a contact between the tool and workpiece.
Needs a relative motion between the tool and workpiece.
Absence of any of these elements – makes the process a unconventional or nontraditional one.
Big boon to modern manufacturing industries.
The need for higher productivity, accuracy and surface quality – led to combination of two or more machining actions, called hybrid machining processes.

4. History of Machining
In ancient days – hand tools (stones, bones or stick).
Later – hand tools of elementary metals (bronze or iron)
Till 17th Century – tools were either hand operated or driven mechanically by very elementary methods.
Wagons, ships, furniture, etc. – were produced.
Introduction of water, steam and electricity – power driven machine tools
Caused a big revolution in 18th and 19th centuries.
1953 – Numerical control machine tools – enhanced the product productivity and accuracy.

6. Traditional or Conventional Machining

7. Metal Cutting Processes

8. Abrasive Machining
Cylindrical grinding
Flat surface grinding

9. Abrasive Machining
Centreless grinding

10. Machining Accuracies 100 -1 microns 1 -0.01 microns 0.1 -0.001 microns
Micro-turning and Micro-Milling M/C
microns

11. Classification of all Material Removal Processes
Area of interest

12. Need for Unconventional Machining
Greatly improved thermal, mechanical and chemical properties of modern materials – Not able to machine thru conventional methods. (Why???)
Ceramics & Composites – high cost of machining and damage caused during machining – big hurdles to use these materials.
In addition to advanced materials, more complex shapes, low rigidity structures and micro-machined components with tight tolerances and fine surface finish are often needed.
To meet these demands, new processes are developed.
Play a considerable role in aircraft, automobile, tool, die and mold making industries.

13. Need for Unconventional Machining
Very high hardness and strength of the material. (above 400 HB.)
The work piece is too flexible or slender to support the cutting or grinding forces.
The shape of the part is complex, such as internal and external profiles, or small diameter holes.
Surface finish or tolerance better than those obtainable conventional process.
Temperature rise or residual stress in the work piece are undesirable.

14. Unconventional Machining Processes - Classification
Electrical 14 14

15. Mechanical Based Processes
AJM
WJM
AWJM
USM
Working principles
Equipment used
Process parameters
MRR
Variation in techniques used
Applications

16. Electrical Based Processes
Working principle
Equipment used
Process parameters
Surface finish & MRR
Electrode/Tool
Power & Control circuits
Tool wear
Dielectric
Flushing
Applications
Electrical
EDM
WEDM 16 16

17. Chemical & Electrochemical Based Processes
CHM
ECM
ECG
ECH
Working principles
Etchants & Maskants
Techniques of applying maskants
Process parameters
Surface finish & MRR
Electrical circuits in case of ECM
Applications 17 17

18. Thermal Based Processes
LBM
PAM
EBM
Working principles
Equipment used
Types
Beam control techniques
Applications 18 18

19. Mechanical based Unconventional Processes
USM – thru mechanical abrasion in a medium (solid abrasive particles suspended in the fluid)
WJM – Cutting by a jet of fluid
AWJM – Abrasives in fluid jet.
IJM – Ice particles in fluid jet.
Abrasives or ice – Enhances cutting action.

20. Thermal based Unconventional Processes
Thru – melting & vaporizing
Many secondary phenomena – surface cracking, heat affected zone and striations.
Heat Source:
Plasma – EDM and PBM.
Photons – LBM
Electrons – EBM
Ions – IBM
Machining medium: different for different processes.

21. Chemical & Electrochemical based Unconventional Processes
CHM – uses Chemical dissolution action in an etchant.
ECM – uses Electrochemical dissolution action in an electrolytic cell.

22. Classification of UCM
Tip Remember

23. Mechanical Based Processes
AJM
WJM
AWJM
USM
Working principles
Equipment used
Process parameters
MRR
Variation in techniques used
Applications

24. Introduction to Abrasive Jet Machining (AJM)
In AJM, the material removal takes place due to impingement of the fine abrasive particles.
The abrasive particles are typically of 0.025mm diameter and the air discharges at a pressure of several atmosphere.

25. AJM

26. Waterjet and Abrasive Waterjet (AWJ) Cutting

27. Abrasive Waterjet and Waterjet examples

28. Mechanics of AJM
Abrasive particle impinges on the work surface at a high velocity and this impact causes a tiny brittle fracture and the following air or gas carries away the dislodged small work piece particle.

29. Ultrasonic Machining

30. Ultrasonic grinding

31. Basics of the USM process
The basic USM process involves a tool ( made of a ductile and tough material) vibrating with a very high frequency and a continuous flow of an abrasive slurry in the small gap between the tool and the work piece.
The tool is gradually fed with a uniform force.
The impact of the hard abrasive grains fractures the hard and brittle work surface, resulting in the removal of the work material in the form of small wear particles.
The tool material being tough and ductile wears out at a much slower rate.

32. Classification of UCM
Tip Remember

33. Schemes of UCM Process
Tip Remember