1. LASER BEAM MACHINING BY
S.PREMKUMAR

2. Process
Capability

3. Laser beam machining process
Laser beam machining process uses highly coherent light source.
This beam can be focused by means of a lens on a very small spot in the work piece.
The high power radiation of laser gives rise to high temperature on a small area of work piece. This initiates the cutting process in the work material.
The equipment consists of ruby crystal placed inside a flash lamp. The flash lamp is used to produce high intensity light rays.

4. The ruby crystal is thus simulated and this produces highly spatial laser beam. When the rays hit the work surface it causes partial or complete vaporization of surface material.

5. Design Consideration Non-reflective workpiece surfaces are preferable
Sharp corners are difficult to produce; deep cuts produce tapers
Consider the effects of high temperature on the workpiece material

6. CHARACTERISTICS
Laser Beam Machining (LBM) is thermal processes considering the mechanisms of material removal.
Laser Beam Machining or more broadly laser material processing deals with machining and material processing like heat treatment, alloying, cladding, sheet metal bending.
Laser stands for light amplification by stimulated emission of radiation.
As laser interacts with the material, the energy of the photon is absorbed by the work material leading to rapid substantial rise in local temperature. This in turn results in melting and vaporisation of the work material and finally material removal.

7. Similarly as can be seen in Fig. 9. 6
Similarly as can be seen in Fig , laser beams can be focused over a spot size of 10 – 100 μm with a power density as high as 1 MW/mm2.
Electrical discharge typically provides even higher power density with smaller spot size.
EBM and LBM are typically used with higher power density to machine materials. The mechanism of material removal is primarily by melting and rapid vaporisation due to intense heating by the electrons and laser beam respectively.

8. VERSATILITY
Laser can be used in wide range of manufacturing applications
Material removal – drilling, cutting and tre-panning
Welding
Cladding
Alloying
Drilling micro-sized holes using laser in difficult to machine materials is the most dominant application in industry.
In laser drilling the laser beam is focused over the desired spot size. For thin sheets pulse laser can be used. For thicker ones continuous laser may be used.

9. 4 Typical application Material removal-Cutting Welding Cladding
Soldering

10. Method used in laser cutting
vaporization
melt and blow
melt blow and burn
thermal stress cracking
scribing
cold cutting
burning stabilized laser cutting

11. Laser Beam welding
LBW is a versatile process, capable of welding carbon steels, HSLA steels, stainless steel, aluminum, and titanium
The weld quality is high. 

12. Laser Cladding
A method of depositing material by which a powdered or wire feedstock material is melted and consolidated by use of a laser in order to coat part of a substrate or fabricate a near-net shape part.
It is often used to improve mechanical
properties or increase corrosion
resistance, repair worn out parts, and
fabricate metal matrix composites.
The powder used in laser cladding is
normally of a metallic nature, and is
injected into the system by either coaxial
or lateral nozzles.

13. Laser Soldering
A technique where a laser is used to melt and solder an electrical connection joint. Diode laser systems based on semiconductor junctions are used for this purpose.
The beam is delivered via an optical fiber to the workpiece,
with fiber Since the beam out of the end of the fiber
diverges rapidly, lenses are
used to create a suitable spot
size on the workpiece at a
suitable working distance. A
wire feeder is used to supply
solder. 

14. Product made by LBM

15. ADVANTAGE OF LASER BEAM MACHINING
Easier workholding
Reduced contamination of workpiece
Reduced chance of warping the material that is being cut
High precision (more precise and using less energy when cutting sheet metal compared to plasma machining)

16. LIMITATION OF LASER BEAM MACHINING
Consume electricity (eg. A typical 1500-watt CO2 laser will have a running cost in the region of £10 - £20 per hour.)
High initial capital cost
High maintenance cost
High purity gas (for the laser generating chamber)
Limited thickness of sheet metal can cut out
compared to plasma machining
Presence of Heat Affected Zone – specially in gas
assist CO2 laser cutting
Thermal process – not suitable for heat sensitive
materials like aluminium glass fibre laminate

17. CHARACTERISTICS Heating,Melting and Vaporisation.
Material removal technique:
Heating,Melting and Vaporisation.
Work material:
All materials except those having high thermal conductivity and high reflectivity.
Tool:
Laser beam in wavelength range of 0.3 to 0.6µm.
Power density:
Max 107 W/mm2.

18. Output energy of laser : 20J
Pulse duration : One millisecond
Material removal rate : 6 mm3/min
Dimensional accuracy : ± 0.025mm
Medium : Atmosphere
Specific power consumption:1000W/mm3/min
Efficiency : 10 to 15%

19. THANK YOU!
from group D….