this slide covers principle, working,advantages and disadvantages of 2 major non conventional machining processes

1. PLASMA ARC MACHINING
&
LASER BEAM MACHINING
PRESENTED BY:-
SHUBHAM CHAURASIYA
PANJAB UNIVERSITY

2. PLASMA ARC MACHINING

3. CONTENTS
Introduction
Working Principle of PAM
 Process Details of PAM
 Applications of PAM
 Advantages of PAM Process
 Disadvantages of PAM Process
Conclusion

4. INTRODUCTION
 The plasma arc machining process was introduced to the industries
in 1964 as a method of bringing better control to the arc welding
process in lower current ranges.
 Plasma-arc machining (PAM) employs a high-velocity jet of high-
temperature gas to melt and displace material in its path.
 Today, plasma retains the original advantages it brought to industry
by providing an advanced level of control and accuracy.

5.  Gases are heated and charged
to plasma state.
 Plasma state is the superheated
and electrically ionized gases at
approximately 5000⁰C.
These gases are directed on the
workpiece in the form of high
velocity stream.
Working Principle of PAM

6. Process Details of PAM
 Plasma gun
 Power supply
 Cooling mechanism
 Work piece

7. Plasma Gun
 The plasma gun consists of a tungsten electrode fitted in the
chamber.
 The electrode is given negative polarity and nozzle of the gun is
given positive polarity.
 A strong arc is established between the two terminals anode and
cathode.
 There is a collision between molecules of gas and electrons of the
established arc.
 Gas molecules get ionized and plasma state is formed.
 Plasma is directed to the workpiece with high velocity.

8. Power Supply and Terminals
 Power supply (DC) is used to develop two terminals in the plasma
gun.
 A tungsten electrode is inserted to the gun and made cathode and
nozzle of the gun is made anode.
 Heavy potential difference is applied across the electrodes to develop
plasma state of gases.

9. Work piece
 Work piece of different materials can be processed by PAM
process.
 Ex: aluminium, magnesium, stainless steels and carbon and
alloy steels.
Cooling Mechanism
 Hot gases continuously comes out of nozzle so there are
chances of its over heating.
 A water jacket is used to surround the nozzle to avoid its
overheating.

10. Applications of PAM
• In tube mill application.
• Welding of cryogenic, aerospace and high temperature corrosion
resistant alloys.
• Nuclear submarine pipe system.
• Welding steel Rocket motor case.
• Welding of stainless steel tubes.
• Welding titanium plates up to 8mm thickness.

11. Advantages of PAM Process
 It gives faster production rate.
 Very hard and brittle metals can be machined.
 Small cavities can be machined with good dimensional accuracy.
Disadvantages of PAM Process
 Its initial cost is very high.
 It is uneconomical for bigger cavities to be machined.
 Inert gas consumption is high.

12. CONCLUSION
 In the latest field of technology respect to welding and machining,
plasma arc welding and machining have a huge success.
 Due to its improved weld quality and increased weld output it is
been used for precision welding of surgical instruments, to
automatic repair of jet engine blades to the manual welding for
repair of components in the tool, die and mold industry.
 But due to its high equipment expense and high production of
ozone, it’s been outnumbered by other advance welding
equipment like laser been welding and Electron beam welding.
 To overcome the mentioned problem, it is been expected that soon
it will fetch with its minimum cons.

14. LASER BEAM MACHINING

15. CONTENTS
 Introduction
 Type of Laser
 Laser Application
 Parameters Affecting LBM
 Advantage
 Disadvantage

16. INTRODUCTION
 Laser beam machining (LBM) is one of the most widely used
thermal energy based non-contact type advance machining
process which can be applied for almost whole range of
material.
 As the name suggest it uses LASER (Light Amplification by
Stimulated Emission of Radiaton ) for operations.
 Laser is a coherent and amplified beam of Light.

17. Laser Beam Machining
 Used light energy from a laser to remove material by
vaporization and ablation
 Energy is concentrated optically
 Laser emits either continuous or pulsed light beam

18. Types of Laser
Types
of
Laser
Gas
Laser
Solid
State
Laser
Excimer
Laser

19. Gas Laser
 Electric current is discharged through a gas to produce a
coherent light
 Operate on the principle of converting electric energy into
laser light output
 Gas acts as pumping medium to attain the necessary
population inversion
 Common gas laser are CO2 Gas Laser, He-Ne Gas Laser

20. He-Ne Gas Laser

21. Solid State Laser
 Constructed by doping a rare earth element into a variety
of host materials
 Pumped optically by arc lamps or flash lamps
 Respond well to Q-switching
 Ruby or Nd:YAG is the most common host material

22. Ruby Laser

23. Excimer Laser
 Uses a combination of an inert gas and reactive gas
 Excimer is form of Ultraviolet Chemical Laser
 Excimer is short for ‘excited dimer’

24. Operation:- Laser Cutting
 Cutting starts by drilling a hole by moving beam
 Cutting speed depends on material and thickness
 Both pulsed and continuous laser is used
 Thickness ranges from 0.5-1 inch
 Used for cutting complex geometry and for clean cutting
operation

25. Laser Application
Heavy
Manufacturing
Seam & spot
welding
Cladding &
drilling
Light
Manufacturing
Engraving
Drilling
Electronics
Skiving of
circuits
Wire
stripping
Medical
Cosmetic
Surgery
Hair
removal

26. Parameter Affecting LBM
• Working Material
• Assist Gases
• Focusing Lenses
• Laser Beam
• Environment
Laser Beam
Machining

27. Advantages
 Non Contact
 No solvent chemical
 Selective material removal
 Flexibility
 Fully automated

28. Disadvantages
 Requires specially trained operators
 Not for mass metal removal processes
 Requires greater control of joint tolerances
 Expensive equipment
 Consumes much energy