Recent developments in non-traditional machining processes, their working principles, equipments, effect of process parameters, applications, advantages and limitations. Comparison of non-traditional machining processes.

1. THERMAL ENERGY BASED
PROCESSES
UNIT -5

2. PRINCIPLE
Here the machining is done by usage of heat
energy.
The heat energy is focused on a particular
portion for melt & Vaporize the work material
Example :
1. Electron Beam Machining (EBM)
2. Laser Beam Machining (LBM)
3. Plasma Arc Machining (PAM)

3. ELECTRON BEAM MACHINING (EBM)

4. PRINCIPLE - EBM

5. ELECTRON
BEAM
MACHINING
(EBM)

6. Cross sectional area of
0.01 to 0.02 mm dia.
To deflect the electro beam
to different spot
10-5 to 10-6 mm of mercury
Temp.
2500°C
Electron accelerated as 1.6×108
m/s by applying 50 to 200 kV
Power density (6500
million W/mm2)
Pulse frequency (1 to 16000 Hz)
and duration (4 to 65,000
microseconds)

7. To avoid collision of accelerated electrons
with air molecules
Vacuum is required (10-5 to 10-6 mm of mercury)
This chamber carries a door, through which the workpiece is
placed over the table. The door is then closed and sealed.

8. ELECTRON GUN
Tungsten filament
Connected to the negative
terminal of DC power supply
Grid cup
Negatively based with respect
to the filament
Anode
Connected to the positive
terminal of DC power supply

9. TYPES OF EBM

10. MECHANICS OF EBM
Electrons are the smallest stable elementary particles with a
mass of 9.109×10-31 kg with a negative charge if 1.602×10-19
coulomb.
• The electron velocity at the striking is given by
Es – Voltage of the electric field, volt
Vs = 600 Es km/s

11. • The electron beam power is given by,
Ib - Beam current, amp
• The electron beam pressure is given by,
𝐼𝑑 − Current density, A/cm2
• The thermal velocity acquired by an electron is given by,
Pb = Es Ib, watts
Fb = 0.34 𝐼𝑑 𝐸𝑠, dyne /cm2
Va =
2Kθ
Ma
m/s
K – Boltzmann’s constant = 1.38×10-23 J/K/atom
θ – Temperature raised, K
Ma – Mass of one atom of the workpiece, kg

12. Process Parameters
The parameters which have significant influence
on the beam intensity and metal removal rate
are given below
Control of current
Control on spot diameter
Control of focal distance of magnetic lens

13. Control of current

14. Control on spot diameter
i) Effect of thermal velocities:

15. ii) Spherical deviation of the
focusing lens

18. Characteristics of EBM process

22. LASER BEAM MACHINING
Photon Emission

23. Differences
.

24. PRINCIPLE OF LASER BEAM PRODUCTION

25. 1.Spontaneous Emission
2.Stimulated Emission

28. TYPES OF LASER
1. Gas lasers
2. Solid lasers
3. Liquid lasers
4. Semi Conductor lasers

29. SOLID LASER
RUBY LASER
Synthetic Ruby rod made up of crystal of aluminium oxide

30. LASER BEAM MACHINING
.

31. LASER BEAM MACHINING
Flash tube filled
with Xenon, argon
or krypton Gases
250 – 1000
watts power
Few
Chromium
Atoms are
placed in Ruby
rod for
absorbing
Green light

32. Cooling of ruby rod is necessary – Because they
are less efficient in high temperature

33. .

34. .

35. MACHINING APPLICATIONS OF LASER
1. Laser in Metal Cutting
2. Laser in Drilling
3. Laser in Welding
4. Laser in Surface Treatment
5. Trimming
6. Blanking
7. Micromachining applications

36. LASER IN METAL CUTTING
• .

37. LASER IN DRILLING
.

38. Laser in Surface Treatment
A thin layer of cobalt alloy coating is applied on
Turbine blade for heat and Wear Resistance.
A thin Ceramic coating is applied on metal
Surface for heat and Wear Resistance.
Its also used to seal the micro cracks which are
usually present in hard – Chromium
electroplates

39. Advantages of LBM
1. All Kind of metals are machined
2. Micro holes are possible
3. Soft materials like rubber can be machined
4. No tool wear and contact with w/p
5. Automated process
6. Controlling of beam is easy

40. 1. High initial Cost
2. Operating cost is high
3. Required skilled labours
4. Rate of production is low
5. Need safety equipments
6. Life of flash lamp is low
7. The machined holes are not straight and round
Disadvantages of LBM

41. PLASMA ARC MACHINING
OR
PLASMA JET MACHINING
IONIZED GAS
High velocity jet of high temp. ionized Gas

42. INTRODUCTION
SOLID GAS or LIQUID
Heated
LIQUID
Heated
GAS
GAS
Heated
FREE electrons and
IONIZED GAS

43. PLASMA GAS
When a gas is heated to a sufficiently high
temperature of the order of 11000 – 28000
degree Celsius, it becomes partially ionized its
known as PLASMA
PLASMA
It’s a mixture of Free electrons + Partially ionized as and Neutral Atoms

44. WORKING PRINCIPLE

45. Plasma arc machining

46. ACCURACY

47. GASES USED IN PAM

48. TYPES OF PLASMA ARC TORCHES

49. Direct Arc Plasma Torch

50. In-Direct Arc Plasma Torch
.

51. • It can be used to cut any metal
• Cutting rate is high
• As compared to ordinary flame cutting
process, it can cut plain carbon steel four
times faster
• It is used for rough turning of very difficult
materials
ADVANTAGES OF PAM

52. • It produces tapered surface
• Protection of noise is necessary
• Equipment cost is high
• Protection of eye is necessary for the operator
• Work surface may undergo metallurgical
changes.
DISADVANTAGES OF PAM

53. Work Material: All materials which conduct
electricity.
Tool: Plasma jet
Velocity of plasma jet: 500 m/s
Power range: 2 to 220 kW
Current: As high as 600 amp
Voltage: 40 – 250 V
Cutting speed: 0.1 to 7 m/min
MRR: 145 cm3/min
CHARACTERISTICS OF PAM