laser induced plasma micro machining

8/18/2019 Laser Induced Plasma Micro Machining

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LASER INDUCED PLASMA MICRO MACHIN

MOHAMMED A

P S

B120292ME

B BATCH


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INTRODUCTION

Micro Manufacturing – Products in range of μm

Products like micro shafts, micro slots , micro gears etc.

Applications in Automobiles, Health & Biotech , IT , Instrumentaetc.

Micro Te"turing – Micro channels, Micro dimples and geometrie

from μm to mm

#sed for surface friction control , Impro$e optical absorption , hdrophobicit.

Applications in Tribolog, Biomedical engineering , Metal cutting

%on$entional processes emploed – Micro 'M & (aser ablation


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MICRO EDM AND LASERABLATION

•

Micro 'M )Material remo$al b ablation $ia generation of plasmagenerated b an electric *eld

• (imitations ) (o+ M, inabilit to machine polmers & ceramics ,

amount of non producti$e cost in$ol$ed.

•

(aser ablation ) Ablation of material due to melting and $apori-atiofacilitated b short pulsed lasers +ith high freuenc.

• (imitations ) Inabilit to machine opticall transparent materials,

dependence of ablation on $arious control factors.


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LASER INDUCED PLASMA MICROMACHINING

•

It is a multi material , tool/less high precision micro manufacturing

• Able to machine materials like ceramics , glass and polmers.

• 0ork piece immersed in dielectric, plasma is generated b dielectric

breakdo+n using laser.

• The plasma absorbs energ and comes in contact +ith +ork piece

• Material remo$al is combined e1ect of mechanical erosion $ia shock

thermal $apori-ation of material due to contact +ith plasma.


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BA!I% !%HMATI% 23 (IPMM P2%!!


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PLASMA GENERATION

• The primar process is the generation of plasma. This is achie$ed +ith the

short high freuenc pulsed laser.

• These lasers ha$e high po+er due to small duration . 0hen focused in diele

high po+er densities.

• 0hen po+er densit e"ceeds threshold ioni-ation potential , results in plasm

generation due to optical breakdo+n.

• Plasma absorbs energ from laser and e"pands.

• The plasma is an opaue , highl locali-ed thermal -one +ith temperature a


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MATERIAL REMOVAL

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Plasma absorbs energ from laser/ plasma interaction.• Absorbed energ is partitioned into mechanical & thermal ener

• Thermal energ causes increase in temperature 894566 7:. Thiconducted to +ork piece through plasma/ +ork piece contact.

• Mechanical energ causes shock+a$es and ca$itation, +hich re

dielectric & appl pressure on +ork piece surface.

• This holds back molten metal, but +hen plasma collapses dieleback and ;ushes out the molten metal.


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MACHINING SETUP


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• 2? laser emitting laser pulses of @ ps duration at 4 nm +a$elength and fre

C6/466 kH- .

• The beam pro*le is Daussian and beam is linearl polari-ed.

• 0orkpiece immersed in dielectric is placed on *$e a"is positioning sstem) transl

rotational '23

• (aser beam is focused using a triplet lens +hich can be adEusted for precise focus.

• At super threshold $alue plasma generated near focal point and brought into conta


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•

'ielectric properties a1ect plasma generation and thus machin

• The desirable properties are)

(o+ absorption coeFcient

(o+ $ariation in absorption coeFcient +ith temperature

(o+ ioni-ation energ

(o+ $iscosit

!uFcientl high dielectric constant $alue

DIELECTRIC PROPERTIES


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LASER PERFORMANCE PARAMETE

• (aser performance parameters a1ect plasma generation and thmachining.

• Parameters that a1ect plasma generation are

C. Pulse repetition rate ) probabilit of formation of plasma depepeak po+er intensit +hich in turn depend of ratio of a$g.

and laser freuenc.

. Plasma discharge duration

. Polari-ation state


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• Micro channels are generated b o$erlapping of adEacent crater

• The degree of o$erlapping craters is determined b feed rate &

dimensions

• !ingle pass micro channels are basic blocks in micromachining

• ' features can be generated b lateral o$erlapping of multipa

channels.

MACHINING MICROCHANNELS


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• Able to machine opticall transparent and re;ecti$e surfaces

•


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CONCLUSIONS

• (IPMM is a tool less , multimaterial micromanufacturing proces

laser induced plasma micro machining

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