laser based manufacturing

Laser Based Manufacturing

What is Laser

LASER is the acronym for Light Amplified Stimulated Emission of Radiation

Laser is a device which generates or amplifies light

Stimulated emission of electromagnetic radiation

Coherent, monochromatic, directional and high power laser beam is used

Elements of Laser

Lasing Medium (Gas, liquid, solid) Pumping process Optical feedback element

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Types of Laser

Gas Laser

Solid State Laser

Excimer Laser

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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

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He-Ne Gas Laser

Source: Google Images

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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

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Ruby Laser

Source: HowStuffWorks

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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’

Source: Google Images

Laser Beam Machining (LBM)

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

LBM schematic.

Schematic diagram of Laser Beam Machine

Physical processes occurring during LBM

Material Removal Mechanism In LBM

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Parameter Affecting LBM

• Working Material

• Assist Gases

• Focusing Lenses

• Laser Beam

• Environment

Laser Beam

Machining

Laser Beam Machining – Capabilities

In laser machining there is no physical tool. Thus no machining force or wear of the tool takes place.

Large aspect ratio in laser drilling can be achieved along with acceptable accuracy or dimension, form or location

Micro-holes can be drilled in difficult – to – machine materials

Though laser processing is a thermal processing but heat affected zone specially in pulse laser processing is not very significant due to shorter pulse duration.

Laser Beam Machining – Limitations

High initial capital cost High maintenance cost Not very efficient process Presence of Heat Affected Zone – specially in

gas assist CO2 laser cutting Thermal process – not suitable for heat

sensitive materials like aluminum glass fiber laminate

Laser Metal Deposition(LMD)

Laser Metal Deposition(LMD) Laser beam creates molten pool on part Metal powder is fed into pool by precision

powder feed system Powder is melted and incorporated into the

pool to create a weld bead

Laser Metal Deposition(LMD)

Valve Ball & Seat Weld Development

Valve Ball & Seat Hardness Profile

Laser Metal Deposition–Capabilities

Metallurgical bond (not mechanical – thermal spray) Wide variety of available powders Very low dilution is possible Relatively high deposition rates Process is highly repeatable Low impact on base material compared to similar

processes (HAZ) Superior metallurgy compared to similar processes Virtually unlimited build height Very flexible tool path compared to wire applications

Laser Metal Deposition–Limitations

High capital equipment costs Powder cost is typically higher than wire Capture ratio of additive material < 100% (based on

process parameters) Cannot control the process manually – CNC is required Experienced, specialized staff required (e.g. laser

safety engineer, skilled operators) Less OEM competition than with traditional

techniques Limited domestic application and equipment support

Selective Laser Sintering (SLS) Parts built up layer by layer A CO2 laser beam selectively melts powder into a

designated shape The component sinks into the bed, a layer of powder

is deposition above the component The process repeats until the component is finished

Selective Laser Sintering Machine

Example of SLS Part (Drill)

Selective Laser Sintering–Capabilities

Robust System and High End Products. Conceptual Models. Functional Prototypes. Pattern Masters for casting. Rapid Tooling. Wide Range of Building Materials. High Throughput Capability. intelligent powder tracking Largest available part size

Selective Laser Sintering–Limitations

Large Amount of Up-Front Capital. Designed for Large Manufacturing Industries. High Maintenance Cost High power requirements for Sinterstation

Process. Requires lots of open space.