1. Unconventional Machining Processes

2. Nontraditional Machining Processes
Overview
Nontraditional Machining Processes

3. Why Nontraditional Machining?
Advanced Difficult-
to-Machine Materials
Challenges for Manufacturing Industry
Stringent Design Requirement
Demand for High Efficiency and Low Cost

4. Why Nontraditional Machining?1
Advanced Difficult-to-Machine Materials
Advanced materials’ increasingly important role
Greatly improved thermal, chemical, and mechanical properties
Greatly improved high strength, heat resistance, wear resistance, and corrosion resistance( eg. PCD)
PCD(Polycrystalline Diamond): Commonly used conventional techniques is diamond grinding, and classical grinding is suitable only to a limited extent for production of PCD profile tools.

5. Why Nontraditional Machining?2
Stringent Design Requirements
Complex 3D Surfaces/Geometric Shapes
Aerofoil
Turbine Blade
Complex Cavity
Non-circular, small and curved holes.
Low Rigidity Structures
Micromechanical Components
Tight Tolerances, High Accuracy
Fine Surface Finishing Quality
long Length to Diameter Ratio Structure
Special profile

6. Why Nontraditional Machining3
Demand for High Efficiency and Low Cost
Uneconomical at low machining pace
Complexity causes Time-Consuming
Advanced Materials causes High-proportion cost

7. Electrolytic Displacement
Comparison of Traditional & Nontraditional Machining Processes
Traditional Machining
Remove Materials based on the shearing process
Non-traditional Machining Process
Ⅰ. Depend on other factors……
Electrolytic Displacement
Mechanical Erosion
Metal Vaporization
Chemical Reaction

8. Comparison of Traditional & Nontraditional Machining Processes
Ⅱ. Easily controlled:
By broad range of in-process inspection sensors
Ⅲ. Computer controlled with respect to process parameters:
Simplifies processes
Accelerates acceptance of the process
Ensures process reliability and repeatability
Ⅳ. Ability to monitor, to respond, to correct undesirable situations automatically

9. Definition of Nontraditional Machining
Mechanical
Nontraditional Processces are categorised by the form of Energy!
Electrical
Thermal
Chemical

10. Sustain productivity with increasing strength of work material
Unconventional Machining Process
Need for Unconventional Machining Process : The industries always face a problem
In manufacturing of components because of the complexity of job profile or
may be due to surface requirements with high accuracy and surface finish .
Therefore to meet such needs of industries , new methods have been developed
called as unconventional machining process. so the conventional methods
( turning , milling , grinding , lapping ) are to be improved by unconventional machining process that can :
Sustain productivity with increasing strength of work material
Maintain productivity with desired shape , accuracy and surface integrity requirements.
Improve the capability of automation system and decreasing the investment cost.

11. Classification of Unconventional Machining Process
Mechanical Energy : Erosion of work material by a high velocity stream
of Abrasives and/ or fluid
Ex. Ultrasonic machining , Abrasive jet machining
Water jet machining
Electrical Energy : Electrochemical energy to remove material
Ex. Electrochemical Machining, Electrochemical grinding,
Electrochemical deburring
Thermal Energy : Thermal energy applied to small portion of surface, removed
by fusion and/or vaporization
Ex. Electro discharge machining ( EDM ), wire EDM ,
Electron Beam Machining , Laser Beam Machining , Plasma Arc Machining
Chemical Energy : Chemical Etchants selectively – using a mask to remove a
portion of the work part
Ex: Chemical Machining / Milling , Blanking , Engraving and
Photochemical Machining

12. Ultrasonic-Machining Process ( USM )
FIGURE (a) Schematic illustration of the ultrasonic-machining process by which material is removed through micro chipping and erosion.
(b) and (c) typical examples of holes produced by ultrasonic machining. Note the dimensions of cut and the types of work piece materials.
The term ultrasonic refers to waves of high frequency generally above the hearing
range of normal human ear i.e. above 20 KHz

13. Ultrasonic Machining of Ceramics

14. Principle of Ultrasonic Machining ( USM )
In the process of Ultrasonic Machining, material is removed by micro-chipping or erosion with abrasive particles.
In USM process, the tool, made of softer material than that of the work piece, is oscillated (vibrated longitudinally ) at a frequency of about 20 kHz with low amplitude of about 0.01 to 0.06 mm .
The tool forces the abrasive grits, in the gap between the tool and the work piece, to impact normally and successively on the work surface,
The impact of hard abrasive grain fractures the hard and brittle surface (abrading action ) resulting in the removal of the work material in the form of small wear particles which are carried away by the abrasive slurry

15. Principle of Ultrasonic Machining
Magnetostictive transducer

16. USM Mechanism
Magnetostictive transducer
Magnetostictive transducers work on the principle of Magnetostriction, that if a piece of Ferro-magnetic material (like nickel) is magnetized, then a change in dimension occurs.
If a high frequency power is supplied to the transducer through winding of coil over it then transducer gets magnetized which causes rapid dimensional change subjected to an alternating magnetic fields i.e. transducer changes polarity of magnetic field and is fed with an A.C supply with frequencies up to 25,000 cycles /sec., converts magnetic energy into ultrasonic energy

17. USM Mechanism
Abrasive Slurry
The abrasive slurry ( mixture of abrasive grains & water of definite proportion) contains fine abrasive grains. The grains are usually boron carbide, aluminum oxide, or silicon carbide ranging in grain size from 100 micron for roughing to 1000 micron for finishing.
It is used to microchip or erode the work piece surface and it is also used to carry debris away from the cutting area.

18. USM Mechanism
Tool holder
The shape of the tool holder is cylindrical or conical, or a modified cone which helps in magnifying the tool tip vibrations.
In order to reduce the fatigue failures, it should be free from nicks, scratches and tool marks and polished smooth.

19. USM Mechanism
Tool
Tool material should be tough and ductile. Low carbon steels and stainless steels give good performance.
Tools are usually 25 mm long ; its size is equal to the hole size minus twice the size of abrasives.
Mass of tool should be minimum possible so that it does not absorb the ultrasonic energy.
The tool material being tough & ductile,
Wears out at a much slower rate.

21. Materials that can be machined on USM
Hard materials like stainless steel, glass, ceramics, carbide, quartz and semi-conductors are machined by this process.
It has been efficiently applied to machine glass, ceramics, precision minerals stones, tungsten.
Brittle materials
Applications
It is mainly used for
(1) drilling
(2) grinding,
(3) Profiling
(4) coining
(5) piercing of dies
(6) Dentistry
(7) Jewellary for shaping precious stones

22. Advantages of USM
Disadvantages of USM
Machining any materials regardless of their conductivity
USM apply to machining semi-conductor such as silicon, germanium etc.
USM is suitable to precise machining brittle material.
USM does not produce electric, thermal, chemical abnormal surface.
Can drill circular or non-circular holes in very hard materials
Less stress because of its non-thermal characteristics
USM has low material removal rate.
Tool wears fast in USM.
Machining area and depth is restraint in USM.