LASER BEAM MACHINING

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LASER BEAM MACHINING

• BY
• S.PREMKUMAR

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Process
Capability
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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.

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• 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.

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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

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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.

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• Similarly as can be seen in Fig. 9.6.1, 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.

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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.

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• 4 Typical application
• Material removal-Cutting
• Welding
• Cladding
• Soldering

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Method used in laser cutting

• vaporization
• melt and blow
• melt blow and burn
• thermal stress cracking
• scribing
• cold cutting
• burning stabilized laser cutting

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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. 

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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.

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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. 

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Product made by LBM
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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)

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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

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CHARACTERISTICS

• 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.

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• Output energy of laser 20J
• Pulse duration One millisecond
• Material removal rate 6 mm3/min
• Dimensional accuracy 0.025mm
• Medium Atmosphere
• Specific power consumption1000W/mm3/min
• Efficiency 10 to 15

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THANK YOU!
from group D.