Laser Micro MachiningBy: Chandrakanth B

•Introduction•Working principle•classification•application•Advantage and disadvantage• safety•Case study•References

Introduction

Laser micromachining: cutting, drilling, welding, or other modification in order to achieve small features.

Micro machining implies that parts are made to the size of 1 to 999 µm. However Micro also means very small in the fields of machining, manufacture of small parts are not easy.

Introduction

Continued...•Lasers have been in use in various industrial sectors such as the automotive and aerospace industries for many years performing cutting, welding and materials processing tasks.

•More recently, there has been an upsurge in the micro engineering applications of lasers where pulsed lasers, in particular, have played a major role in the development of numerous micro-systems technology (MST) areas.

Working Principle

• A laser machine consists of the laser, mirrors for beam guidance, a focusing optic and a positioning system.

• The laser beam is focused onto the work piece and can be moved relative to it.

• The laser machining process is controlled by switching the laser on and off, changing the laser pulse energy and other laser parameters and by positioning either the work piece or the laser focus.

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• Laser is emitted from the source is passed through the energy attenuator. After it is passed through the beam homogenizer to homogenize the beam.

• The target illuminator and machine vision controls the beam to the focusing lens. The lens is moved by precision motion stages. The beam is then falls on the work piece and the machining takes place.

Types of Laser Micro Machining

1. Direct writing.

2. Mask Projection

Process Parameters

Effect

Wavelength,Focal length of lens

Feature size

Beam shape Feature shape

Beam energy,Pulse width

Size of heat affected zone

Depth of focus Aspect ratio

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Practical

Resolution

Limit

Attainable

Aspect

Ratio*

Taper Undesirable

Side Effects

Status of Technology

Development

Excimer

Laser5 mm >100:1 yes Recast Layer low

CO2 Laser 200 mm 100:1 yes Recast Layer,Burring,

Thermal

high

Nd:YAG 50 mm 100:1 yes Recast Layer,Burring,

Thermal

high

EDM 100 mm 20:1 No Surface finish moderate

Chemical Etch 250 mm 1:1.5 Yes Undercutting moderate

Mechanical Ø 100 mm 10:1 No Burring moderate

Comparison of Available Machining Methods

For drilling micro holes, laser beam drilling

technique is used.

Applications

High speed drilling of 20µm holes in 50µm thick foil

Cutting of 1mm tube

100µm wide v-grooves

Laser Micro machining technique finds application in the manufacture of micro channels and micro holes in integrated chips and microchips.

Micro holes on integrated chips Micro channels on integrated chips

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Surface micro machining is characterized by the fabrication of micro mechanical structures from thin deposited thin films.

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Used in machining threads in a single polyfibre and also used to give taper to the fiber.

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•Easy capability of being automated•Straightforward process monitoring•Forceless and contactless machining•Minor heat-affected zone•Marginal modifications to the microstructure•Machining free of burr and bulging•High flexibility regarding design of tiny structures•High machining speed•High precision•Constant machining quality•No additional tooling costs by wear•No solvent chemicals used•Material removal rate controllable down to the nanometer scale

Advantages

•The equipment required for micro machining is very costly than other cutting processes.•Need highly skilled persons to operate micro machining systems.•Material limitations (including crystalline and reflective materials)•Reflected laser light can present a safety hazard

Disadvantages

•High intensity ultraviolet and infrared light hazardous to the eyes (cornea) and skin•All manufacturers required by law to design and certify compliance with U.S. Code•During normal operation of the equipment Interlocked protective housing is must.•Required safety labels, inspections and record keeping.

Safety

Mechanical safety• Large motion control systems may pose mechanical hazards to people• Mechanical guards• Machine must be checked regularly

• Lethal high voltages in the laser head• Electrical safety covers• Qualified service personnel only

Electrical safety

• Toxic and corrosive fluorine and chlorine gases• Compressed gas cylinders need proper handling

Material safety

•Micro machining technology not only provides a new manufacturing route for existing products, but also allows the creation of completely new products.

•The surface micro machining technology predominates at the present state & this trend will continue in the future.

•Nano is the buzz word of the moment. Thus the transition from Micro-Electro-Mechanical-Systems (MEMS) to Nano-Electro-Mechanical systems (NEMS) is taking place in present technology

Conclusion

•Advancements in Laser Micro machining Techniques- By Nadeem Rizvi and Paul Apte.•Laser Micromachining – By Udo Klotzbach, Andres Fabian Lasagni, Michael Panzner and Volker Franke.•www.resonetics.com•Internet(wikepedia,google etc)

References

Thank you