Cms Tutorial

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Industrial Strength Laser Marking:

Turning Photons into Dollars

Control Micro Systems, Inc.4420MetricDriveWinterPark,FL32819407-679-9716

www.cmslasermarking.com

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PrefaceTheoriginalinspirationforthisdocumentwasthegrowingconcernwithinthelasercommunityaboutitsroleineducatingindustryonthebenefitsoflaserprocessing.Afterseveralafter-hoursdebates,weconcludedthatthereisnosinglesourceforalloftheinformationaprospectiveuseroflasermarkingmightrequire.Thisdocumentisourattempttohelpremedythatsituation.

Theobjectiveofthispublicationistoeducatethereaderonthevariousaspects,featuresandcapabilitiesofbeam-steeredlasermarkingsystems.Itattemptstoprovideageneralunderstandingofthelasermarkingtechnology-withouttheprerequisiteofamathematicsorengineeringbackground.

Althoughtheprimaryintentistoeducate,thereis

admittedlyadegreeofsalesmanshipinourmotives.ControlMicroSystemsis,afterall,amarkingsystemmanufacturer.Wehopethatthisdocumentwillservetostimulatethereadertofurtherconsiderthepotentialbenefitsoflasermarkinginhisorhermanufacturingfacilities.Ifwealsoservetoenlightenthosewithamoregeneralinterestinlasersandindustriallasermarking-somuchthebetter.Todaysstudentcouldbetomorrowspioneer.

Thecontentsaredividedintoeightchaptersandfourappendices.Chaptersone,two,andthreedelveintothebasicsoflaseroperationandthedesignofbothNd:YAGlasersandbeam-steeredlasermarkingsystems.Chaptersfourandfivereviewtheprinciplesofthelasersinteractionwithmaterialsandthemethodsthatareemployedtocontroltheinteractionandcreatealasermark.Chapters

sixandsevencoverthesubjectsofintegratinglasermarkingsystemswithhostcomputers,automatedworkcells,etc.,andthetypicalcostofoperation.Thefinalchapter,perhapsthemostimportanttothoseconsideringutilizinglasermarkingtechnology,analyzesthelasermarkingcostjustificationprocessthroughareviewofpresentcostjustificationtechniquesandseveralcasestudiesofpresentusers.

Theappendicesprovideadditionalinformationonlasermarkingascomparedtoothermarkingtechnologies,amatrixofawidevarietyofmaterialsandtheircompatibilitywithlasermarking,asectiononlasersafetyonthemanufacturingfloor,andinformationontheuseoflasermarkerswithintheautomotiveindustry,thesinglelargestusertodate.

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ForewordThelaserhastouchedalmostallaspectsofourlives.Itisarguablythelastgreatinventionofthetwentiethcentury.Sinceitsdevelopmentin1960,thelaserhasfoundahomeinscientificresearch,medicaldiagnosisandtreatment,andindustrialmanufacturing.SmalllaserdiodesareutilizedforCDplayers,laserjetprintersandtelephonecommunications.Hundredsofthousandsoflasersareused

forUPCbarcodescanninginstoresandsupermarkets.

Lasersarethebasisforadvancedmilitaryrangefindersandmissileguidancesystems.Large,multikilowattcarbondioxide(CO2)lasersareusedtocutandweldautomotiveframesandbodypanels.Thelistgoesonandonandcontinuestogrow.

Almosteverytypeofcommerciallyavailablelaserhas

foundanapplicationinmanufacturing.Diodelasers,helium-neonlasers,ionlasers,excimerlasers,helium-cadmiumlasers,carbon-dioxidelasers,andthevarioussolid-statelasershaveallbeenincorporatedinthemanufacturingprocess.Ofthediverserangeoflasersandlaserapplications,thelargestutilizationofsolid-state

Nd:YAG(Neodymium:YttriumAluminumGarnet)lasersisforlasermarking.Forthisreason,thispublicationfocusesprimarilyontheNd:YAGlasermarkingsystem.However,manyofthebasicprinciplesareapplicabletobeam-steeredlasermarkingsystemsutilizingothertypesoflasers.

Thepopularityoflasermarkingisprimarilytheresultofitsthreemostnotableprocessfeatures-thepermanenceofthemark,thehighspeedofthemarkingprocess,andthespeedatwhichthemarkingimagecanbechanged.Thesethreeattributesmostdifferentiatebeam-steeredlasermarkingfromallothermarkingtechnologies(seeAppendixA).Althoughtheacquisitioncostsoflasermarkingarehighascomparedtoothermethods,thesavingsthatresultcanbesubstantial.

Inthisdocument,wewillreviewtheattributesandfeaturesoflasermarkinginthecontextofdesign,function,andmanufacturingvalue.Wehopeyoufinditeducationalandentertaining.

Enjoy!

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Photon AbsorptionOnemethodinwhichanatommaygainenergyistoabsorbaphotonoflight.Tobeabsorbed,thephotonmustcontainenergyequaltothedifferencebetweentwooftheallowedenergylevelsoftheatom.Becauseaphotonsenergydeterminesitswavelength,theatomwillonlyabsorblightofspecificwavelengthsthatareequaltotheallowedenergylevels.

Spontaneous Em issionTherearetwowaysinwhichanatomcan subsequentlyloseenergy:bytransfertoanotheratomorbyemittingaphotonoflight.Whenemittedaslight,theemittedphotons

wavelengthwillcorrespondtotheenergylostbytheatomasitmovesfromahighenergylevelbacktoalowerlevel.Thelightemittedbyanatommustcorrelatewiththeallowableenergylevelsfortheatom.

Normallyanatomwillabsorbenergy,raisingittoahigherenergylevel,andwillremaininthatenergystateforsomeperiodoftime(nanosecondsormilliseconds).Thisperiodisthespontaneousorupper-levellifetimeoftheatom.

Eventuallytheatomwillspontaneouslyemitaphotonoflightinarandomdirectionandreturntothegroundstate.Thisisspontaneousemission(fig.3).

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Stimulated Em issionAnothermechanismbywhichanatomcanemitlightisbystimulatedemission(fig.4).Duringthespontaneouslifetimewhiletheatomisinanupperlevelstateandbeforespontaneousemissioncanoccur,theatomcanbestimulatedtoreleaseitsphotonoflightbyinteractingwithanotherpassingphoton.Thepassingphotonswavelengthmustbeequaltothedifferenceoftheelectronsupperandlowerenergylevelstostimulatetheatomtoemitaphoton.Becausetheemittedphotonswavelengthisdeterminedbythedifferencebetweenthesameenergylevels,thepassingandemittedphotonswillbethesamewavelength.Inaddition,bothphotonswilltravelintheoriginaldirectionof

thepassingphotonandwillbeinphase.Withequalpropertiesofwavelength,direction,andphase,thephotonsconstitutecoherentlight.

Thisstimulatedemissionofcoherentlightiscrucialtotheoperationofalaser.Infact,thisisthestimulatedemissionreferredtointheacronymLASER.

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Itispossibletoforceanenergydistributionoutofequilibrium(fig.6).Ifsomeoftheatomsinthegroundstate(E0)areforcedtoanupperlevel(E1)beforeanyoftheexistingupperlevelatomscanspontaneouslydecaybackdown,apopulationinversioniscreatedinwhichthereare

moreatomsintheupperlevelstatethanthelower.Thepopulationinversionisanonequilibriumdistributionandwillnotlastverylong.Groundstateatomsmustbecontinuouslyforcedintotheupperleveltomaintaintheinversion.Asustainedpopulationinversioniscrucialtomaintainingstimulatedemission.

Population InversionUptonow,wehavelookedattheenergytransitionsofasingleatom.Whatoftheenergydistributionofalargepopulationofatoms?

Inanysubstantialpopulationofatoms,themajorityoftheatomswillbeinthegroundstate.Theremainingatomswillbedistributedamongthehigherenergylevelsindecreasingquantities.Boltzmannslaw,oneofthefundamentallawsofthermaldynamics,dictatesthepopulationateachlevel.Infigure5,eachenergylevelforaspecifiedatomisrepresentedontheverticalaxisofthediagramwhilethelengthofthecorrespondinghorizontallinesrepresentsthepopulationforeachlevel.Asdescribed

byBoltzmannslaw,eachascendinglevelwillhavefeweratomsthantheprecedinglevel.Thepopulationofatomsisinathermalequilibriumdistribution.Applyingheattothepopulationtoincreasetheenergywillsubsequentlyincreasethenumberofatomsabovethegroundstatebutwillnotchangetheoveralldistribution(i.e.ahigherlevelwillnotcontainmoreatomsthanalowerlevel).

Light AmplificationSohowdoesthelaseramplifylight?Attheheartofall

lasersisthelasingmedium,whichcontainsatomsthatcanbestimulatedtospontaneouslyemitlight.Themediummaybeagasmixture(CO2,helium-neon,etc.),asemiconductorsubstrate(laserdiodes),aliquid(dyelasers),orasolidcrystal(Nd:YAG,Nd:YLF,Ruby,etc.).Thelaserwillalsohaveanenergysourcetoexcite(pump)theatomsofthemedia.Thepumpsourcewillusuallybeeitheranelectricdischarge,lightfromahi-intensitylightsource,oranother

laser.

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Allofthephotonswillbethesamewavelength,willbeinphaseandwilltravelthesamedirectionalongthepathofreflection.Thepopulationinversionassuresthatthereisalwaysasufficientquantityofatomsintheupperlevelstatetosustainthelasingprocess.Oneofthemirrorsofthe

opticalfeedbackiscoatedtoleakasmallpercentage(typically10%orless)oftheamplifiedlightreflectingbetweenthemirrors.Thisleakageisthelaseroutputbeam.

Asthepumpsourceexcitesthelasingmedia,sufficientenergyisappliedtocreateapopulationinversionandinitiatespontaneousemission.Thespontaneouslightemittedbythemediatravelsinrandomdirections(fig.7).

Opticalfeedbackiscreatedbyplacingamirrorateachend

ofthemediatoreflectthosephotonstravelingalongthelongitudinalaxisbackintothemedia.Thereflectedphotonscauseotherupperlevelatomstoemittheirphotonsbystimulatedemission.Asthisprocesscontinues,onephotonbecomestwo,twobecomefour,fourbecomesixteen,etc.-LIGHTAMPLIFICATION!!

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Chapter 2 -Nd: YAG Lasers

ThepumpsourceisusuallyakryptonarclamppositionedparalleltotheNd:YAGcrystal(fig.8).BoththeNd:YAGcrystalandthekryptonarclamparelocatedinsideagold,ellipticalshapedcavity.Thecavitycontoursarecarefully

calculatedtofocusallofthepumplightemittedbythekryptonlamptoafocalregionalongthecenteraxisofthe

ThebasicprocessoflaseramplificationdescribedinChapter1,thoughignoringmanyofthesubtletiesoflaserphysics,appliestoalllasers.Nowwewilllookspecificallyatthesolid-stateNd:YAG(Neodymium:YttriumAluminum

Garnet)laserthatismostfrequentlyemployedforbeam-steeredlasermarking.

Thelasingatomsinsolid-statelasersareembeddedinasolidpieceoftransparentmaterialcalledthehost.ForNd:YAGlasers,neodymium(Nd)atoms(thelasingmedia)areembeddedinayttriumaluminumgarnet(YAG)crystalhost.TheYAGcrystalisusuallyintheshapeofarodroughlythesizeofapencil.Theoptimumneodymium

concentrationinthecrystalisabout1%byweight.Itsgrowthisbestdescribedasablackart.

Thoughdifficultandexpensivetoproduce,theNd:YAGrodexhibitsdesirableoptical,mechanical,andthermalpropertieswhichmakeitanexcellentmediaforhighpowerlasingoperation.

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Nd:YAGcrystal.Goldisusedforitshighreflectivitytothewavelengthofthepumplight.A100%reflectiverearmirrorandapartiallytransmittingfrontmirrorprovidetheopticalfeedback.

AfourstepprocessofenergytransferoccursinanNd:YAG

crystal(fig.9).First,theneodymiumatomsareelevatedtooneoftwoupperenergylevelswiththeabsorptionoflightemittedbythekryptonarclamp.Lamplightinpumpbandsnear0.73mmand0.8mmismostefficientatexcitingneodymiumionstotheupperlevels.Theatomsthengothrougharapid,nonradiativedecaytoametastableupperlaserleveltherebycreatingapopulationinversionbetweentheupperandlowerlaserlevel.Whentheatomsfurtherdecaytothelowerlaserlevel,energyisemittedasaphotonoflightwithawavelengthof1.06mm.Thislasertransitionisthesourceofboththespontaneousandthestimulatedemissionthatconstitutethelaserbeam.Lastly,theatomsexperienceanonradiativedecaybacktothegroundstatetorepeattheprocess.

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Multimode vs. TEMoo OperationAtthispoint,thelaserisoperatinginwhatisreferredtoasamultimodecondition.Withoutdelvingdeeplyintolaseropticalmodes,sufficeittosaythatacrosssectionofamultimodebeamwouldshowmultiplehotspotsorrings(fig.10)andthediameterofthebeamwouldberoughlydeterminedbythediameteroftheNd:YAGcrystal.

Becausethereflectedlightinthecavityispartiallyblocked,TEMoooperationisachievedattheexpenseofloweroveralloutputpoweralthoughthequantumoflightinthecenterofthebeammaybehigher.

Forspecialapplicationsthatrequireonlynarrowlinewidths(


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The Acousto-Optic Q-SwitchForlasermarkingapplications,anadditionalopticalcomponentisusuallyaddedtotheopticalcavity-theacousto-opticQ-switch.TheQ-switchisadevicethatproducesapulsedlaseroutputbyalternatelyblockingandunblockingthepathofreflectionbetweentheopticalfeedbackmirrors.TheQstandsforthequalityoftheopticalfeedbackofthelasercavity.

Theacousto-opticQ-switchconsistsofatransparentmaterial(usuallyquartz)withapiezoelectricacoustictransducerbondedtooneside(fig.12).Inthestaticstate,thelightemittedfromtheNd:YAGcrystalpassesthroughtheQ-switchatanangledictatedbythematerialsnormal

indexofrefraction(fig.13).Thelightthenreflectsofftherearmirror,passesbackthroughtheQ-switch,andreturnstothecrystal.

WhenanRFsignalisappliedtothetransducer,anacousticwaveisprojectedthroughthequartzthatmomentarilycompressesthematerial.Thisproducesaperiodicchangeintheindexofrefractionofthequartz.SomeofthelightpassingthroughtheQ-switchisdiffractedtoasmallangle andmissestherearmirror.Withthislossoftheoptical

feedbackthatisnecessarytostimulateemission,lasingactionceases.

Neodymiumisafairlyuniquelasingmediainthatitexhibitsacomparativelylongspontaneousorupper-levellifetime.DuringtheperiodthattheRFisappliedtotheQ-switchandstimulatedemissionissuspended,thepopulationoftheupperlaserlevelwillcontinuetogrowasmoreatomsabsorblampenergy.Atomsalreadypopulatingtheupper

levelwillnotimmediatelydecaytothelowerlevelduetothelongupper-levellifetime.Duringthenon-lasingperiod,theupperlevelstoresconsiderableamountsofenergy.WhentheRFsignalisremovedandtheopticalfeedbackisrestored,theresultantburstoflaserlightcanbeseveralkilowattsofpeakpower.Q-switchingisanexcellentmethodtoproduceveryshortpulsewidthandveryhighpeakpowerpulsesoflightfromacomparativelylowpowerlaser.

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*Tip:Thelongupper-levellifetimewhichresultsinhighpeakpowerpulsesduringQ-switchedoperationwilldetrimentallyeffectthemarkingoperationduringthemuchlongerperiodthatoccurswhilethesteeringmirrorsarerepositioningbetweencharactersorgraphicimages.Allstate-of-the-artmarkingsystemsshouldincludeapulsesuppressioncircuittosuppressthegiantpulsewhichoccursatthebeginningofanynewcharacterorimage.

Intra-Cavity Sa fety ShutterThefinalcomponentfoundinthelasercavityistheelectricallyactivatedsafetyshutter.Thesafetyshutteralsoblocksthepathofreflectionbetweentheopticalfeedbackmirrors.UnliketheQ-switch,thesafetyshutterisa

mechanicaldevicedesignedtoblockthelasingactionforlongperiodsoftime.Allsafetyshuttersaredesignedsothatgravitywilldroptheshutterintotheclosedornon-lasingposition,intheeventofanelectronicfailure.

Thefollowingtablesummarizestypicalperformancespecifications,includingQ-switchpulsecharacteristicsfortheNd:YAGlasersthatarefrequentlyusedforlasermarking.

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Nd:YAG Laser Typical Performance Specifications

15 watt 50 watt 100 wattTEMoo Multimode Multimode

CW Performance

CW Power (min.) (watts) 8 50 100

Instability (max.) (% RMS) 3 3 3

Beam Diameter @1/e2 (mm) 1 4 6.5

Beam Divergence @1/e2 (max.) (mr) 2.5 10 10

QS Performance @ 1 kHz

Peak Power (min.) (kW) 15 75 120

Energy / Pulse (min.) (mJ) 1.9 12 20

Pulse Width (max.) (nsec) 130 160 170

Peak Power Instability (max.) (% p-p) 6 8 15

QS Performance @ 10 kHzPeak Power (min.) (kW) 2.4 18

Energy / Pulse (min.) (mJ) 0.6 4

Pulse Width (max.) (nsec) 260 220

Peak Power Instability (max.) (% p-p) 15 15

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Support E lectronics/Cooling SystemsTheNd:YAGlaserrequiresavarietyofsupportelementstooperatecorrectly(fig.14).

ThekryptonarclamprequiresastableDCpowersource

deliveringapproximately110VDCatupto35amps.Thepowersupplymustalsoincludeastartcircuittoapplyahigh-voltageignitionpulseacrossthelamp.

Thestabilityofthepowersourcewilldirectlyaffectthestabilityofthelaseroutput.Thehigh-intensitykryptonlampgeneratesaconsiderableamountofheatthatmustberemoved.

ExcessheatcandamagetheexpensiveNd:YAGcrystal,

damagethegoldplating,orreducethekryptonlampsoperatinglife.Toremovetheexcessheat,Nd:YAGlasersarecooledbyaclosed-loop,deionizedwatersystem.DeionizedwaterisnecessaryforitshighopticaltransparencyandlowelectricalconductivitysinceboththeNd:YAGcrystalandthekryptonarclampareimmersedinthewaterflow.TheheatissubsequentlyremovedfromtheDIwaterbyawater-to-waterheatexchangerconnectedtoanoutsidewatersource.

Foroptimumperformance,theDItemperatureisregulatedbymeansofasolenoidthatturnstheoutsidewaterflowonandoffasrequired.RegulationoftheDIwatertemperaturetowithinafewdegreesfurthercontributestothestabilityofthelaseroutputandthemarkingprocess.

Thetransducerintheacousto-opticQ-switchrequiresanRFpowersource.ForoperationoftheQ-switch,theRF

sourceispulsedatfrequenciesfrom1to50kHzcorrespondingtothedesiredpulserateofthelaser.ThequartzcellinsidetheQ-switchisalsowater-cooled,butitissimplyplumbedinparallelwiththeprimarycoolinglinestothelaserhead.

Acontrolunitprovidestheoperatorand/orthecomputerwiththemeanstoadjustthelaseroutputpower,adjustthepulserateoftheQ-switch,setthepositionofthesafety

shutter,andmonitorsthelasersoperationandperformance.

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Chapter 3 Marking System Design

Thebeam-steeredlasermarkingsystemdeflectsthelaserbeamacrossthesurfacemuchlikeapencilonpaper.Wherethepencildepositslead,thehighintensitylaserlightaltersthematerialtocreateacontrastingimage.Simplystatedbutnotsosimplydone.

Output Power vs. Energy DensityWhendiscussingbeam-steeringopticsdesigns,itisimportanttounderstandthedifferencebetweenthelasersoutputpowerandthepowerdensityorbrightnessofthelaserbeamattheworksurface.

Acontinuouswave,50-wattlaserproducesthesameamountoflightasa50-wattlightbulb.Thelightbulb,designedforgeneralillumination,emitsitslightinalldirections.Unlikethelightbulb,thelasercompactsallofitslightintoanarrowbeam.Theenergydensity,usuallyexpressedaswattspersquarecentimeter,isanexpressionnotonlyoftheamountoflightemittedbythedevicebutalsohowmuchlightispresentinaspecificarea.Thelightbulbproducesverylowenergydensityilluminationwithverylittlelightpersquarecentimeterwhilethelaseremitsaveryhighenergydensitybeamoflight.

Thesameprinciplesapplytoafocusedlaserbeam.Alaserproducing50wattsoflightdistributedovera0.003"diameterspotwillyieldconsiderablyhigherenergydensitythenalaserthatdistributesthe50wattsoveralarger0.005"diameterspot(fig.15).Asyoumayhavesurmised,thetruemarkingpowerofasystemistheenergydensityproducedatthemarkingsurface,notsimplytheoutputpowerofthelaser.

Infact,itisnotunusualtohavealowerpowerlaserwithasmallerfocusedspotsize,engravedeeperthanahigherpowerlaserwithalargerspotsize,althoughwithanarrowerlinewidthduetothesmallerspotsize.Theloweroutputpowerlaser,bycompactingitslightintoasmallerspot,hasahigherenergydensityattheworksurface.

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Delivery Optics DesignsTheoutputbeamoftheNd:YAGlaserisdirectedandfocusedbyopticalcomponentslocatedinthegalvanometerblock(fig.16).Beam-steeringisaccomplishedbytwomirrorsmountedonhigh-speed,highaccuracy

galvanometers.ThegalvanometersaremountedtoprovideindependentbeammotiononboththeXandY-axisofthemarkingfieldandarecrucialtoproducingahighqualitymarkingimage.

Therearepresentlytwodesignsforfocusingthelaserbeamatthemarkingsurface.Bothdesignsutilizeanopticaltelescopecalledanupcollimatortoenlargethebeamandafocusinglensassemblytosubsequentlyfocusthebeamon

themarkingsurface.Theupcollimatorincreasesthediameterofthelaserbeampriortofocusing.Althoughthismaysoundcounter-productive,thediameterofthefocusedspotisdeterminedbythediameteroftheincomingbeamandthefocallengthofthelens.Asthediameteroftheincomingbeamincreaseswithupcollimation,thefocusedspotwillbecorrespondinglysmallerandtheenergydensityhigher.As

anaddedbonus,thelargerbeamdiameterreducestheenergydensityatthesurfacesofthesteeringmirrorstoinsurelongterm,reliableoperationwithoutthermaldamage.

Thepracticallimitationtoincreasingthebeamdiameteristhesizeofthesteeringmirrorsthatarerequiredtodirectthebeamwithoutclippingordistortion.Asthebeamdiameterincreases,theincreasedmassofcorrespondingly

largermirrorsreducesthemaximumtravelspeedanddetrimentallyeffectspositioningaccuracy.Eachmanufactureroptimizesthecombinationofupcollimationratioandmirrorsizetoachievethebestoverallperformance.

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Pre-focus Delivery O pticsThetwodesignsdifferafterupcollimationofthelaserbeam.Thepre-focusdesignplacesasimplefocusinglensaftertheupcollimatorbutbeforethebeam-steeringmirrors(fig.17).Thisdesignrequiresarelativelyinexpensive

focusingassemblyandcanprovidelargediametermarkingfields.

Onedisadvantageofthisdesignisalargefocusedspotsizeandcorrespondingreducedenergydensity.Bothresultfromthelongfocallengthsthatarerequiredtoaccommodatethedistancefromthelenstotheworksurface(seelensperformancespecificationsforrelationshipofspotsizetofocallength).Also,becausethe

focallengthofthelensisfixed,thefocalpointfollowsanarcasthemarkingbeamsweepsacrossthemarkingfield.Asthebeamtravelsfromthecentertotheedgeofthefield,thefocalpointiselevatedabovetheworksurfaceduetothependulumeffect.Thebeamdiameterandenergydensitywillchangedramaticallyacrossthefield.Somesystemshaveattemptedtocompensatebymechanicallyadjustingthefocallengthtomaintainthefocalpointonaflatplane.

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Post-focus Delivery OpticsThemorepopularpost-focusdesignplacesamulti-element,flat-fieldfocusingassemblyafterthebeam-steeringmirrors(fig.18).Themulti-elementlensismorecostlythanthesimplelensusedinpre-focusdesignsbut

providesthesignificantadvantageofopticallymaintainingthefocusedspotonaflatplanethroughoutthemarkingfield.Themarkingcharacteristicsandimagequalitywillremainconsistentthroughoutthemarkingfieldwithoutresortingtomechanicalcompensation.

Post-focussystemsareavailablewithavarietyoflensoptionstotailorthesystemsperformancetothespecificapplicationrequirements.

Theperformancetableonthefollowingpagecharacterizestypicalflat-fieldlensperformancecharacteristics.Ingeneral,longerfocallengthswillprovidelargermarkingfieldsattheexpenseoflargerfocusedspotsizesandreducedenergydensity.Thedesiredlinewidth,markingdepth,andmarkingspeedmustallbeconsideredinselectingthecorrectlensforaspecificjob.Fortunately,allofthemajormanufacturershaveapplicationslaboratories

thatwillassistpotentialusersinmakingthecorrectlensselection.

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Operating SoftwareThemostsignificantadvancestooccurinlasermarkingtechnologyhavebeenintheareaoftheoperatingsoftware,primarilyduetotherapidadvancesinpersonalcomputers.Thefirstgenerationlasermarkingsystemsutilizedbulky,

slowmainframecomputerswithteletypekeyboardsforoperatorinputandpapertapeforprogramstorage(andthesewereconsideredstate-of-the-artatthetime!).LatergenerationsincorporatedthethennewPCwithvideomonitorsandfloppydiskstoragebutcontrolledlittlemorethanthemarkingimageandthebeammarkingvelocity.

TodaysmarkingsystemsfeatureGraphicalUserInterfaceenvironmentsonavarietyofoperatingsystemplatforms

andcontrolallaspectsofthemarkingprocessincludingthemarkingimage,allofthelaseroperatingparameters,andinteractivecommunicationswithpartshandlingcontrollersandhostcomputers.Itisnotunusualfortodaysmarkerstoruninfullyautomated,unassistedmanufacturingenvironmentsfor24hoursaday.

Itisbeyondthescopeofthispublicationtodetailallofthenumerousfeatures,benefits,andcapabilitiesofthe

differentsoftwaresystemsthatareavailable.Anyattemptwouldbecomeabookinitsownrightwhenconsideringthesoftwarecustomizationthattheuserorvendorcanaccomplishtotailorthesystemsoperationtoaspecificapplicationandmanufacturingenvironment.Someexamplesofcustomconfigurationsareprovidedinthechapteronsystemintegration.

Howefficientlywillitgetthejobdone?Remember,for

greaterthan90%ofthetimethemarkingsystemisamachinetool.Programming,drawing,etc.willeffectlessthan10%ofthesystemsproductivityandresultantcostsavings.

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Flat-Field Lens Performance SpecificationsFocal Length 3 5 8

Field diameter (in) 3 5 8

Working distance (in) 2.38 7.38 11.5Depth of field (in) 0.059 0.133 0.200

Line thickness (in) 0.0025 0.004 0.008

Resolution (in/step) 0.0002 0.0003 0.0005

Power density (Mwatts/cm2) 524 223 102

Measurements taken with 50-watt multimode laser output.

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Chapter 4 Process Principles

Lasermarkingisanon-contact,thermalprocessrelyingontheheatgeneratedbythelaserbeamtoalterthesurfaceoftheworkpiece.Toachievethedesiredresults,themarkingsystemprovidestheoperatorwithseveralmeansof

controllingthethermalreactioneithermanuallyand/orbycomputercontrol.

Pulse RateAfterestablishingtheoverallquantumoflightamplificationwiththelampcurrent,theoperatormayadjusttheQ-switch

pulserate(seeChapter2,TheAcousto-OpticQ-Switch).TheQ-switcheffectivelydividesthelaseroutputintopulsesoflight(fig.19).Tobestunderstandthephenomena,visualizetheQ-switchedlaserasanopticalcapacitor.amp Current

Increasingordecreasingtheelectriccurrenttothekryptonarclampadjuststheoutputpowerofthelaser.Asthecurrentischanged,thelightoutputfromthelampandtherateoflaseramplificationincreasesordecreases

accordingly.

Muchlikeanelectriccapacitor,thelaserstoresenergy(intheupperlaserlevel)duringthenon-lasingperiodsbetweenpulses.

WhenthelaserispulsedbytheQ-switch,theoutputisaburstoflightcontainingmostofthestoredenergy.Ifthepulserateissettoalowfrequency(1kHz),thecomparativelylongdurationbetweenpulseswillproduceveryhighpeakpowerpulseswithverynarrowpulsewidths(app.100nanoseconds).Ifthepulserateisincreasedto10kHz,thepeakpowerwillbemuchlowerduetotheshorterchargetimebetweenpulses.

Whatdoesthismeantothetargetmaterial?Thehighpeakpowerpulsesatlowfrequencieswillincreasethesurfacetemperatureveryrapidlyresultinginmaterialvaporizationandminimalheatconductionintothepart.Athigherreprates,thelowerpeakpowerwillproducemuchless,ifany,vaporizationbutwillresultinsignificantlymoreheatconduction.Thegreaternumberofpulsesinagiventimeframewillalsoincreasetheheatconductedintotheworksurface.TheQ-switchpulserateisprobablythemost

importantvariableforcontrolofthethermalprocess.Aswiththelampcurrent,thepulseratecanbecontrolledeithermanuallyorbythepartprogram.

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Beam V elocity (Marking Speed)Afterthelaseroutputhasbeenconfiguredwiththelampcurrentandpulserate,theoperatormustestablishthebeamvelocityformarking.

Inaperfectworld,everyapplicationwouldrunatthemaximumspeedforthehighestsystemthroughput.Inlasermarkinghowever,thebeamvelocityisanotherimportantvariableinthethermalprocessandmustbesettoachievethedesiredprocessresults.Fordeepmarking(typically>0.002")eachpointontheengravedlinewillrequireexposuretoseveralpulsestoachievedepth.Thebeamvelocitymustbereduceduntilthedesireddepthisachieved(fig.20).Forshallowmarking,thespeedmaybe

increasedtothesystemsmaximumvelocityoruntiltheseparationbetweenpulsesisaestheticallyunacceptableattheselectedpulseratesetting.Asageneralrule,pulsesshouldoverlapatleast50%togivetheappearanceofacontinuousengravedline.

*Tip:Someofthemoreadvancedsystemsrepositionthebeambetweencharactersand/orgraphicimagesindependentlyoftheprogrammedmarkingspeed.As

example,somesystemswillrepositionthemarkingbeamatover32,000mm/secondregardlessoftheprogrammedmarkingspeedforconsiderablyfastercycletimes .

Determiningthebestcombinationoflampcurrent,pulserate,beamvelocityandlensselectionisanartdevelopedafteryearsofdevelopinglaser-markingapplications.Theexpertisetomakethisdeterminationresidesinthemanufacturersapplicationslaboratory.Theapplications

techniciansaretheonlypeoplefullyqualifiedtodeterminethebesthardwareconfigurationandtheoptimumprocessparametersforayourapplicationontheirequipment.Allseriouslasermarkermanufacturershavethiscapability.

AVAIL YOURSELF OF THIS SERVICE!

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Color-Darkcolorsabsorbmorelightthanlightercolors.Thisisequallytruewiththeabsorptionoflaserlight,althoughthedifferenceisusuallymarginalrequiringaminoradjustmenttothelaseroutputpower,themarkingspeed,orthelaserspulserate.Paintedcolorshavelittleeffectsincethelaserusuallyvaporizesawaythepaintvery

quicklyandexposesthecolorofthebasematerial.

Surfacefinish-Thesurfacefinishofatargetpartisnotacrucialfactorinthethermalprocessitselfbutmaybeimportantforreadabilityconsiderations.Ifthelaserdoesnotinduceacolorchange,aroughsurfacewillrequiredeepengravingtoachievealegibleimagewiththesurroundingmaterial.Asmooth,machinedsurfacewillyieldexcellentreadabilitywithveryshallowengraving.

MaterialHardness-Forallpracticalpurposes,materialhardnessisnotafactorinlasermarking.Thelasercanmarkahardenedsteelpartjustasreadilyastheuntemperedmaterial.

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C


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Chapter 5 Applications

Dependingonthematerial,acontrastingmarkcanbecreatedusinganyoneofthreedifferenttechniques.Themaximumtemperatureachievedonthematerialsurfacedifferentiateseachmethod.

Surface Annea lingComparativelylowtemperaturescanbeappliedtometallicstoannealthesurface(fig.22).Themarkingbeamwillproduceasharp,contrastinglinetothesurroundingmaterialwithveryshallowmaterialpenetration.Markingbyannealinghastheadvantageofnotdisruptingthesurfacethatisimportantforsomemedicalapplications,specifically

implantabledevices.Thedisadvantageisthat,becausetheprocessreliesonheatconductingintothematerial,thebeamvelocitymustbeheldcomparativelyslow.

Surface M eltingAsanalternative,thematerialcanbebroughttoamoltenstate(fig.23).Thistechniqueisseldomusedwithmetallicsasitoffersnorealadvantages.Itisfrequentlyemployedtoinduceacolorchangeinplastics.Awidevarietyof

commercialplasticsyieldexcellentcolorcontrastandhighqualitymarkingimages.

Althoughtheprocessalsoreliesonconductedheat,thespeedscanfrequentlybeveryreasonablesincetheprocessrequireslessdepththanthatrequiredannealingmetallics.Excellentresultsareroutinelyobtainedatpenetrationdepthsoflessthan0.001".

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Material Vaporization (Laser Engraving)Thethirdandmostcommonmethodistheremovalofmaterialbyvaporization(fig.24).Thistechniquehastheconsiderableadvantageofspeed.Becausethematerialisalmostinstantlyvaporizedwitheachpulse,thebeam

velocitycanbesettothefastestspeedpossiblethatstillachievesthedesireddepthandmaintainsacceptablepulseoverlap.

Multiple Color EngravingAninterestingvariationofthismethodhasbeendevelopedfortheautomotiveindustrytoproducemulticolorengraving(fig.25).

Thedashboardsoftodaysautomobilescontainawealthofbutton-activatedcontrols.Pushbuttonsareemployedtocontroldrivinglights,interiorlights,air-conditioningandheatingsystems,stereosystems,windshieldwipers,andevenon-boardcomputers.

Thebuttoncapsaremoldedfromacolored,translucentplasticandaresubsequentlypaintedwithawhitebasecoatandadarker,contrastingtopcoatcomplementingthecolor

schemeofthevehiclesinterior.Thelasermarkingsystemselectivelyremovesthedarktopcoattoexposethewhiteundercoatcreatingthedesiredtextand/orgraphiclegend.Thecontrastbetweenthetwocolorsprovidesexcellentdaytimevisibility.Fornightvisibility,thebuttonisbacklittoprojectthecolorofthetranslucentplasticthroughtheengravedlegend.

Chapter 6 System Integration


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Chapter 6 -System Integration

AsthemanufacturingsectorcontinuestoautomateproductionprocessesandincorporateJust-In-Time(JIT)manufacturingphilosophies,beam-steeredlasermarking

systemsareincreasinglycalledupontofunctionaseitheranelementoflarger,computercontrolledmanufacturingfloorsorasacontrollerforintegratedmarkingworkstations.Parallelwiththedevelopmentofthemarkingsystemsimagegenerationsoftware,developershaveaddedhighlysophisticatedandflexiblecontrolandcommunicationfunctionstokeeppacewiththedemandsofincreasinglyelaboratemanufacturingarchitectures.

Unattended Operation under Host ControlNissanMotorshasplacedahighpriorityonautomatingthe

manufacturingprocesswhileretainingtheflexibilitytorunspecialsandcomponentrework.Lasermarkershavereplaceddot-impactprinterstoincreasetheproductionrateoftheVehicleIdentificationNumber(VIN)tagsandtoaddbarcodecapability.EachVINtagconsistsofthevehiclesuniqueIDnumberinbothbarcodeandman-readableformatsandagraphicsymbolrepresentinganairbagwhenappropriate.Thetotalcycletimerequiredtoproduceatagisunder10seconds.Toachievefullutilization,themarking

systemwasdesignedtoaccommodateVINtagsforanyofthetruck,automobileandbusassemblylinesandisnetworkedwithaDECVAXMainframehostcomputer.

Followingaretwoexamplesoflasermarkingsystemsintegratedwithlargermanufacturingarchitecturesthatdemonstratesomeofthepossibilities.

Thepartstransfersystemconsistsofoneupstackerloadedwithblankplates,threedownstackerstoreceivecompletedplatesforeachofthethreeassemblylines,andanejectionchuteforspecialsandrejects.Thetagsaretransportedbetweenthestackersbyavacuumpick-and-placetransfer

mechanism.Eachstackerisadjustabletoaccommodatetagdimensionsuptoamaximumof6"by6"andwillholdasufficientquantityoftagstorununattendedforseveralhours.

Themarkingsystemcomputerutilizesinfraredfiber-opticsensorstomonitorthepositionandvolumeoftagsineachofthestackers.Approximately45minutespriortotheupstackerrunningoutofblanktags(withapproximately250

tagsremainingintheupstacker),theoperatorisforewarnedthattheupstackerwillneedtobereloadedandthecompletedtagsremoved.

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Deionized water filtersThefinalconsumableistheDIwaterfilter.Filterscostapproximately$72.00apiece,dependingonquantitiespurchased,andshouldbereplacedabouttwiceayearforanannualcostof$144.00.Thehourlyratewouldbreak

downto$0.07/hourassuming40hoursperweekoperation.

Total operating costsAlltotaled,theworst-casecostofoperationwouldbe$1.10perhour.Inreality,userswillnotexperiencethisworst-casescenarioandcanexpectactualoperatingcostswellbelowa$1.00perhour.

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Alloftheseelementscanbecategorizedintooneoftworeturn-on-investmentstatistics,tangiblesavingsor


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intangiblesavings.Tangiblesavingsarethosethatareeasilyquantifiableindollars.Examplesoftangiblesavingsare:

Reducedwork-in-processcapital

Reducedlead-time,piececosts

andbetterschedulingdecisionsreducethecapitalfundstiedupinwork-in-process.

ReducedLabor

Reduceddowntimeformaintenanceandrepair

Reducedoreliminatedtoolcosts

Thesecanbetheeliminationofcontactwear

expensessuchastoolresharpeningandreplacement,theeliminationofdowntimetochangetooling,ortheeliminationoftoolinginventory.

Reducedoreliminatedconsumablesdisposalcosts.

Tangiblesavingsarerelativelyeasytoidentify.Intangiblesavingsareanothermatter.Herearetwomore

quotesfromAMT,oneonthepresentstateofintangiblebenefitsanalysisandtheotherontheavailabilityofrelevantinformation...

Theintangiblebenefitsofautomationinvestment,theleastunderstood,areoftenignoredinmanyevaluations.

Goodinformationisoftenavailableregardinglaborandmaterials.Detaileddataisnottypicallymaintainedinareassuchascustomerserviceorinmeetingproductionschedules.Neitherdogoodrecordsexistforoverheadactivitieswhichmaybereducedbyanautomationinvestment.

Whenincorporatinglasermarkinginamanufacturingprocess,significantsavingsarefrequentlyrealizedfromtheintangiblebenefits.Theymustbeincludedaspartofacompleteandaccurateanalysis.

Intangiblesavingscanbefoundinseveralareasofthemanufacturingprocess.Costreductioncanbefoundin

(1) qualityandreliabilityimprovementssuchasreductionofreworkandscrapandpartinspectioncosts,

(2) responsivenesstothemarketplacewithshorterproductioncycletimes,reducedleadtimes,andthecapabilitytorespondmorequicklytoshort-termchangesinmarketdemand(eithervolumeorproductmix),

(3) productionflexibility/efficiencysuchastheeliminationofsecondaryprocesses,thegreaterpotentialforcustomizedproduction,andpossibleincreasedmarketshareandsalesrevenuesduetohighercapacitiesand/orfasternewproductintroductions,

(4) increasedcustomerserviceandsatisfaction,

(5) improvedcompetitivepositioningwithnewtechnologies,

(6) reducedfloorspacerequirements,

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(7) improvementsinoverheadsuchasreducedsafetycosts(includinginsurance)andreducedi l i i l i l d h d h li i i d i f


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managerial,engineering,clericalandshopsupportcostsduetotheeliminationorreductionofnon-valueaddedactivities,.34

(8) inventoryimprovementssuchasreducedsafetystock,lowerproperty(inventory)tax,andreducedfloorspacerequirements,

(9) andtheimpactonhumanresourceswithincreasedemployeemoraleandsafetyandthebenefitsofupgradedemployeetechnicalskills.

Theexerciseofestimatingtangiblecostsavingsbasedontheseandotherintangiblebenefitswillprovidefor

thetranslationofimprovedmanufacturingflexibility,productqualityandcustomerservicetoanincreaseinsalesrevenue.

thetranslationofhigherqualityandreliabilitytoreductionsinwaste,scrapandrework.Qualitycontrolbudgets,warranty,andpotentialrecallexpensescanalsobeimproved.

theconversionofareductioninnon-valueaddedactivitiessuchasmovingproductandwork-in-processqueueintoreducedproductcostandimprovedcashflow,especiallywiththeeliminationofsecondaryprocesses.

estimatingincreasedproductivityandqualityduetoanimprovedworkenvironment.

Thefollowingcasestudiesillustratethepurchasedecisionsofsomepresentusersandboththetangibleandintangiblesavingstheyenjoyedafterinstallation.Theintentisnottolistalloftheareasofsavingsbuttohighlightonlythoseareasthateachuserfeltwassignificanttohiscompanysbottomline.

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Case Study #1


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Situation:Amanufacturerappliedpartinformationtoinvestmentcastingspriortoshipmentutilizingavibropeenengraver,anelectro-etchmarkingsystem,orinkstampmachine.Thetotalmarkingdepartmentcostswere$33.90perhourexcludingtoolingcosts.

Theannualtoolingcostsassociatedwiththevibropeenmarkingaloneconsistedofstylusresharpeningof6,112pieces@$0.95/each($5,806total)andstylusreplacementof2,400pieces@$9.40/each($22,560total)fortotaltoolingcostsof$28,366peryear.

Analysis:Costsavingswerecalculatedforthetangiblesavingsofapplyinglasermarkingto70%ofthevibropeenworkload.Afteranalyzingthepotentialsavings,aturnkeymarkingsystemwaspurchasedwhichincludedaworkstationdesignedtoacceptthe

manufacturerspartscarts,alaserchiller,factoryinstallationandoperatortraining,andabasicsparepartskit.

Thetotalpackagecostwas$90,869.00.

Tangible Savings:Themarkingtimeperpiecewasreducedfrom2minutesto30seconds.Theincreasedproductionrateto120piecesperhourrealizedareductioninpiececostfrom$1.13eachto$0.28each(-75%)basedontheoriginal$33.90/hourdepartmentcosts.

Thereductioninpiececostscombinedwiththeeliminationof70%ofthetoolingresharpeningandreplacementcostsyieldedatotalannualsavingsof$72,875.00.

Intangible Savings:Theimprovedmarkqualityandconsistencyeliminatedreworkandscrapwhilesignificantlyreducingpartinspectionlabor.

Capitalsavingswererealizedwiththeeliminationofthetoolinginventory.

Withtheeliminationofcarpaltunnelinjuries,savingswererealizedinsafety,insurance,andworkerefficiency.

Inthefuture,thelasermarkerwillreplacetheelectro-etchprocessforadditionalsavingswiththeeliminationofasecondarycleaningprocess,areductionindowntimeandmaintenance,andtheeliminationof chemistry disposal.

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Case Study #2


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Situation:AmanufactureracidetchedpartnumbersontheODofcircularhardenedsteelparts.Acidetchingwasathree-stepprocess,wash/dry,etching,andneutralization.

Uniquetoolingwasrequiredforeachsizepart.

Thewashingsolventwasexpensiveandreadilyevaporatedmakingthewashingstepamajorcostintheprocess.Washingrequiredfrequentdowntimeforsolventchangesandreplenishment.

Differentmarkingstencilswererequiredforeachpartnumber.Suddenstencilfailurecausedunacceptablemarkingquality.

Theacidetchprocessrequiredconstantoperatormonitoring.

Acidetchinghadtobedonepriortoparthardening.Partsrejectedlaterinmanufacturing

cyclecouldnotbereworkedandhadtobescraped.Thedisposalofsolvents,acid,andneutralizerwascostlyandhazardoustotheenvironmentwithseveralEPArestrictions.

Thetotalcostincludinglaborwas$0.069/eachat4,000pcs./shift.

Analysis:Costjustificationwasbasedonpotentialsavingsassociatedwiththesolvents,processtooling,andlabor.

AfullyautomatedmarkingsystemwaspurchasedincludingaU-shapedpassthroughconveyorsystemwithautomatedin-feedandout-feedto/fromthebulkloadingstation.Thetotalpackagepricewas$210,000.00.

Tangible Savings:Thepiececostwasreducedto$0.002/each(-97%)includinglabor.

Downtimeformaintenanceandrepairwasreduced

Thetoolingcostswereeliminated.

Consumablescostswerereducedandthecostsofchemistrydisposalwereeliminated.Intangible Savings:Theimprovementinqualityeliminatedreworkandscrap

Productionefficiencywasimprovedwiththeeliminationofsecondaryprocesses

Rejectscouldbereworkedbyperformingthemarkingprocessafterparthardening

Inventoryreduction

Moreresponsivetomarket

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Case Study #3


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Situation:Amedicaldevicemanufacturermarkedpart,size,andlotnumbersoncobalt-chrome,titaniumandstainlesssteelorthopedicimplantsandsurgicalinstruments.

MarkingwasaccomplishedwithaMonodeelectro-chemicalsystemthatutilizedmanuallytypedstencilsforeachmarkingimage.

Eachpartrequired1.2minutestotypethestencil,etchthepart,thenneutralize,washanddrythepartatatotalcostof$0.46includingallconsumables.

Analysis:Costjustificationwasbasedonexpectedsavingsfromeliminationofthemultiplestepsinthemarkingprocessandeliminationoftheconsumables.

Amarkingsystemwitha36"rotarydialandathrow-awaybubblefixturemachinewaspurchasedfor$110,500.

Tangible Savings:Productivitywasincreasedto104,000partsperyear

Partmarkingcostswerereducedto$0.25/each(-45%)

Automationofprocessreducedlaborexpenses

ReduceddowntimeEliminatedconsumablesanddisposalcost

Intangible Savings:Useofparttrayshaseliminatedtedioushand-locatinglabor

Improvedqualityhassignificantlyreducedrework

Improvedqualityandpermanencehasincreasedmarketshare

TheuserhasstatedthatMoreimpressiveplanttourshascontributedtoanincreaseinmarketshare

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Case Study #4


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Situation:Amanufacturerofhighprecisionfluidpressuregaugesproducedtwentydifferentmodelswithcasediametersfrom2to5.5inches (fig.26).InventoryreductionandJITeffortswerehinderedbygaugeinaccuraciesastheproductwasreceivedfrommanufacturing.

Tocompensateforinaccuracies,eachmodelrequiredfivesilk-screenedfaceplatestoaccommodatedeviationsinmeasurementranges,hysteresis,andlinearity.Aninventoryvolumeof100differentfaceplateshadtobemaintained.

Eachgaugewasindividuallymeasuredandmatchedwiththefaceplatewhichmostaccuratelyapproximateditscharacteristics.Thisstepwasdonebyhandincurringsignificantlaborcosts.

ThemeasurementdeviationsandJapanesestandardsonthelinewidthofthesilk-

screenedticmarkseliminatedthemanufacturersproductfromtheJapanesemarket.

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Development P latform:A marking s stem as de eloped based on a t o position


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Amarkingsystemwasdevelopedbasedonatwo-positionrotarytablewithavisionstationandamarkingstation (fig.27).Atthevisionstation,eachgaugeispressurizedanditaccuracy,linearity,andhysteresiswereestablishedwithaCCTVsystem.Thedatacollectedwasusedtogeneratealinearitycurveforeachgaugewhichwasfurtherrefinedbycomparisonwiththehistoricaldataofallpreviousmeasurementsforthatmodel.

Thelinearitycurvethenbecamethebasisforauniquemarkingprogramcreatedon-the-flyforthemarkingstation.Thecustomfaceplate,engravedatthemarkingstation,exactlymatchedthebeginningandendingpoints,full-scale

linearity,andhysteresisforeachgauge.

Results:Totaltimetoprocessagaugerangedfrom42to90secondsdependingonpartdiameter.Laborforassemblyandcalibrationwasreduced50%.

Silk-screencostsfromtheoutsidevendorwereeliminated.

Useofoneblankfaceplateforeachmodelreducedinventory95%.95%.

Reworkduetoout-of-speclinearitywasreduced98%.Reworkduetoout-of-speclinearitywasreduced98%.

Highaccuracywith0.001"linewidthticmarkshasopeneduptheJapanesemarket.Highaccuracywith0.001"linewidthticmarkshasopeneduptheJapanesemarket.

Fasterresponsetimeforcustomorderswithenduserslogoand/orpartnumberhasincreaseddomesticmarketshare. Fasterresponsetimeforcustomorderswithenduserslogoand/orpartnumberhasincreaseddomesticmarketshare.

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IllclosethischapterwithtwofinalquotationsfromAMT...

Whenperformingcostjustificationanalysisofautomationprojects,theconsequencesofnotinvestinginautomationisthefirststrategicissue.

Thenatureofautomationprojectsisoftensuchthatinitialimplementationphasesinthemselvesmaynotyieldsavings,butarenecessaryinordertorealizesignificantsavingsfromfuturephases.

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Summary

Thi l d l ki t t i l I h l d th t littl ith t dd i th t I l t t


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Thisconcludesourlasermarkingtutorial.Ihopeweclearedthewateralittlewithoutmuddyingupthestream.IalsowanttoextendmyapologiestothoseengineersandscientistswhorecognizethelibertiesIhavetakenwithmuchofthephysicsoflaseramplificationanditsinteractionwithmaterials.

Theappendicesprovideadditionalinformationthatmaybehelpfulbutdidnotfindaplaceintheorganizationofthismanual.

AppendixAcomparesbeam-steeredlasermarkingtoothermarkingtechnologiesinthecontextofspeed,permanence,andimageflexibility.AppendixBisalistofmanyofthemorecommonmaterialsandtheircompatibilitywithNd:YAGlasermarking.AppendixConLaserSafetyshouldbereviewednotonlytogetaclearerpictureoftherequirementsbuttoquellsomeoftheeffectsoftoomanyStarWarsfans.AppendixDisareviewofsomeoftheapplicationspresentlybeingusedintheautomotiveindustry,thelargestuserindustryofbeam-steeredlasermarkingsystems.Perhapsnotsurprisingly,weencourageanyreaderswithcontinuinginterestinlasermarkingtocontactControlMicroSystems.

Happy lasing!

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Appendix A -Laser vs. Other Marking Technologies


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Marking Process Speed Permanence Image Flexibility LaserMarking Good Good Good

ChemicalEtch Good Good Poor PhotoEtch Good Good Poor

Ink-Jet Good Poor Good

MechanicalStamping Good Good Poor

Nameplates(1) NA Moderate Poor

Casting/Molding Good Good Poor

PneumaticPin Moderate Good Moderate

VibratoryPencil Poor Good Good

CO2MaskMarker Good Moderate Poor

(1)Therearenumerouslaser-markingsystemsbeingusedtoengravenameplatesasameansofapplyingtheadvantagesoflasermarkingtoproductsthataretoolargeand/ortooheavytobringtothelasermarkingsystem.

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Appendix B - Material Suitability to Laser Marking.


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Material (in alphabetic order) Image Contrast Material (in alphabetic order) Image ContrastCarbon Resin GoodCeramics Bare Good

Goldplated Good

Lacquercoated Good

Glass Poor CO2LaserGood

Inconel Graphite GoodKovar (gold-plated) GoodMetallics Aluminum

Anodized Excellent

Bare Good

Blackoxidecoated Excellent

Brushed Good Cast Good

Galvanized Good

Painted Excellent

Copper

Brass(bare) Good

Brass(coatedlacquer) Good

Bronze Good

Copper(bare) Poor

Copper(nickelcoated) Good

Castiron Good

Cobalt Good

Germanium Good

Gold Poor

Silver Good

Titanium Excellent

Steel

Cadmiumcoated Good

Carbonsteel Excellent

Caststeel Good Chromeplated Good

Hardened Good

Nickelplated Excellent

Oxidecoated Good

Springsteel Good

Stainless(polished) Excellent Stainless(unpolished) Excellent

Steelalloy Good

Stressproofsteel Good

Surgicalsteel Excellent

Untreatedsteel Good

PC board Bare Good

Coatedfiber Good

Fibersubstrate Poor

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Material (in alphabetic order) Image Contrast Material (in alphabetic order) Image ContrastPlastics ABS Excellent Rubber Poor


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Acrylic Good

Delrin Poor

DIPplastic Good

Epoxy Good

Lexan Excellent

Lucite(clear) Good

Lucite(paintedblack) Good

Melamine Poor

Mylar(withsilvernitratecoating) Good

Nylon(withglassfill) Good

Nylon(Zytall) Good

PES(polyether-sulfone) Excellent

Phenolic Good

Plaskon Good

Polycarbonate Excellent

Polyethylene Good

Polyurethane Good

PVC Excellent

Rynite Good

Ryton Poor

Styrene Excellent

Teflon Poor Thermalreinforcedresin Good

Valox Good

Vandar Good

Wood PoorMarkabilityestablishedusingapost-focus,50wattNd:[email protected].

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ForthosefewuserswhoneedaClass4lasersystem,aroomofappropriatedimensions,constructedofdrywall,woodorsimilaropaquematerialthatwillabsorbthepowerofthelaserbeam,isusuallysufficient


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sufficient.

Withadvanceplanningandpreparation,lasersystems,whetherClass1orClass4,canbeeasilyinstalledtoassuremaximumoperatorsafety,comfortandefficiency.

This information is provided as a guide only!MoredetailedinformationisprovidedinANSIZ136.1,TheAmericanNationalStandardfortheSafeUseofLasers.CopiesmaybeobtainedbycontactingtheLaserInstituteofAmerica,12424ResearchParkway,Orlando,Florida32826,(407)380-1553.

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Turnkey Engineering


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OurApplicationsLabistheonlytestingfacilitythatemploysasdiversearangeofsolid-stateandgaseouslaserstoestablishthetechnicalandeconomicfeasibilityofyour

application.Weutilizelaserpowerlevelsfromseveralmilliwattsaveragepowerto50joulesperpulsemaximumpulseenergy.Laserwavelengthsspanfromthenearultravioletthroughthevisibletothefarinfrared.Wearetheonlycompanywiththeresourcesnecessarytodeterminethebestlaserforyouruniquemarkingrequirements.

Software E ngineeringThecomputerisapowerfulimagingtoolthatprovidesspeed,versatilityandseamlessintegrationwithmanufacturingcontrolsandinformationnetworks.Oursoftwareengineerscanaugmentourstandardsoftwarepackageswithcustomoperator/machineinterfacestofullyintegratethelasermarkerintoyourmanufacturingarchitecture.CustomfunctionalitycanbeaddedincludingODBCdatabaseutilizationandproductionreporting.Wecanassistyourengineeringstaffinimplementingthebest

imagegeneration,imagemanipulation,andprocesscontrolsolutionsforyouruniquemarkingrequirements.

Systems E ngineeringTheSystemsEngineeringgroupprovidesstandardandcustomparts-handlingworkstationsformanual,semi-automated,andfullyautomatedproduction.Manufacturingcellsincorporatemulti-axistablesandrotarydrives,

vibratorybowlfeeders,conveyors,pickandplaceparttransferandrobotics.Secondaryprocessesincludingvisionsystemsandreaderscanbeincorporatedforestablishingthemarkingimageorsubsequentprocessconfirmation.Forthehighestefficiency,ourengineerscanintegratethelasermarkerintoyourexistingparttransfersystem.Whetheryouneedastandalonesystemorafullyintegratedmarkingworkstation,ourunique,unitizeddesignswillassureyouofmaximumproductivityandreliabilitywithminimumfloor

spacerequirements.

Continuous Flow Eng ineeringControlMicroSystemsisapioneerincontinuousproduct

flowmarking.Withadvancedbeamsteeringcomponentsandproprietaryimagingsoftware,ourmarkerscanapplytextwithoutstoppingtheparttosubstantiallyincreasethethroughputofyourlasermarker.Ourengineerscandetermineifyourapplicationcanbenefitfromcontinuousflowmarkingtechnology.

Control Micro Systems, Inc.4420MetricDriveWinterPark,FL32819407-679-9716www.cmslasermarking.com

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