refinishing equipment textbook (ref01e)
TRANSCRIPT
REF01e-STMAN1-E
RefinishingEquipment(REF01e)Textbook
Module1-Spray Guns
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 7
Learningobjectivesforthismodule include:
• describingthevarioustypes, designs,andpartsofaspraygun.
• explainingtheimportanceof cleaningandmaintainingaspray gun.
• describinghowtosetupahigh volumelowpressure(HVLP)spray gun.
Gravityfeedspraygunsarecommontypesoftools usedforrefinishing.
Spraygunsusedforrefinishingmaybe differentdesigns.Someoftheseare:
• highpressure(HP).AnHPspray gunuseshighpressure,low volume air.Theinletairpressures foranHPrangefrom70to90 poundspersquareinch(psi).This typeofspraygunmayalsobe referredtoasconventional.HP spraygunsareconsideredold technology.
• highvolumelowpressure(HVLP). AnHVLPspraygunoperatesby
highvolumeandlowpressureof airpassingthroughthespraygun. Theinletairpressureisabout45 psiwithanaircap pressureof10 psiorless.
• reducedpressure(RP).An RPspraygunusesareduced inlet pressureof32psithatallows optimizedhighpressuretoacheive transferefficiencyabove65%, eventhoughthegundoesnot have10psiorlessattheaircap. Thistypeofspraygunisprimarily usedforhighsolidclearcoats, asitaidsintheatomization andevaporationofsolventsand reducerstoallowforanimproved transferofmaterial.
Lowvolumelowpressure(LVLP)spray gunshavelimiteduseandavailability.
Theamountofairpressurethatis producedbyanaircompressoris measuredinpsi.Cubicfeetperminute (cfm)isthevolumeofairdeliveredthat isrequiredforatooltooperateproperly. Smalleraircompressorsmaynotbeable toproducethehighairvolumerequired forHVLPsprayguns.Mostairtoolsused inarepairfacilityrequirelesscfmthan thetoolsusedforrefinishing.Anexample ofthisistheDynalocke dual-action(DA) sanderwhichrequires3cfm,whereasan HVLPspraygunisupwardsof25cfm.
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ShownareHVLPgravity(left)andsiphon(right) feedsprayguns.
Spraygunsmaybe:
• gravityfeed.Gravityfeedspray gunsoperatebythepaintcup beinglocatedabovethespray gunbody.Fluidwillflowoutof agravityfeedspraygunwhen thereisnoairpressureandthe triggerispulled.Thisisbecause materialmovesthroughthespray gunbygravitationalforceandnot vacuum.
• siphonfeed.Asiphonfeedspray gunhasthepaintcuplocated belowthespraygunbody.The materialisdrawnoutofthespray gunbyvacuumcreatedbytheair cap.Atmosphericpressureinside thepaintcupforcesthematerial upthroughthespraygunbody andoutofthefluidneedle.
Pressurefeedsprayguns,thoughcommon atonetimeintheindustryforspraying refinishmaterials,arenowtypically usedtoapplychip-resistantcoatingsand corrosionprotectionmaterials.Apressure feedspraygunoperatesbypressurizing
thecupwhichaidesinallowinghigher viscositymaterialstobeatomized.
HVLPallowsformorecontroloftherefinishmaterial, whichaidesintransferefficiency.
Transferefficiencyistheamountof materialasprayguncandepositon asurface.Thematerialthatisnoton theintendedsurfaceisconsidered overspray.
AnadvantageofusinganHVLPisthatthe useoflowerpressuresallowsformore controlofthematerialbeingsprayed. ThetransferefficiencyofanHVLPspray gunistypically65%orbetter.Thiscan beaffectedbymanyvariables,including spraytechnique.Severalwaystoincrease transferefficiencyaretouse:
• therecommendedspraygunsetup forfluidneedle,fluidnozzleand aircapselection.
• asmallerspraypattern.Thiskeeps therefinishmaterialfocusedon thepanel.
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Partsofaspraygunthatmayrequire frequentcleaningandadjustmentinclude the:
1. aircap,whichislocatedonthe topofthespraygun.Theairports ontheaircapdirectairflowpast thefluidnozzle.Astheairpasses bythefluidnozzle,avacuumis createdandthepaintalsogets atomized.
2. fluidnozzle,whichismatchedto thefluidneedleandmustbekept insets.
3. fluidneedle,whichmovesinand outofthespraygunandcanbe adjustedtoregulatetheamountof fluiddelivered.
4. spraygunbody,whichhouses,or hasattachedtoit,alloftheparts thatmakeupaspraygun.Spray gunbodiesalsohavewithinthem alloftheairandfluidpassages.
5. trigger,whichisthecontrolforthe fluidneedlevalveandairvalve.
6. paintcup,whichmaybe locatedinavarietyofpositions. Dependingonthetypeofspray gunbeingusedthepaintcup couldbelocatedabove,below,or attachedbyahose.
7. fluidcontrolknob.Adjusting thefluidcontrolonaspraygun changestheamountoffluidthat isreleasedoutofthespraygun. Thespraypatterncanbeadjusted fromalightdustingtoadeposit ratethatwillcauseruns.
8. fanadjustmentknob,whichis usedtochangethespraypattern ofthespraygun.Thespraypattern
canbeadjustedfromasmall circletoanoblongspraypattern.
Refertothe“Animation:GravityFeed SprayGun”inthepresentation.This animationshowshowrefinishmaterial andcompressedairflowthroughaspray gun.
Shownarethethreedifferentairpassageswithinthe aircap.
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Shownareseveraldifferenttypesofaircaps.
Anaircaphaspassagesthatdirectairpast thefluidneedle.Thesepassagesarethe:
• centerhole. • auxiliaryholes. • airhornholes.
Thetypeofaircapmayalsoaffectthe amountof:
• fluidflowthroughthespraygun. • airpressureneeded.
Thefullatomizationofrefinishmaterialoccursin threestages.
Thesepassageswithintheaircaphelp achievefullatomizationinthreestages. Duringthe:
• firststage,arushofairfromthe centerholecreatesavacuum at thefluidtip.Asairisdirected acrossthefluidpassages,a pressuredifferenceoccurs.Thisis duetothecreationofaventurior vacuum.Therefinishmaterialis pulledinbythevacuumandair turbulencestartstobreakupthe refinishmaterial.
• secondstage,partiallyatomized refinishmaterial ishitbyanair streamfromtheauxiliaryholes andtherefinishmaterialisfurther atomized.
• thirdstage,airfromtheairhorn holeshitstheatomizedrefinish materialandcausesittoformthe spraypattern.
Shownisafluidneedle.
Thefluidneedleis:
• openedandclosedbythetrigger. • usedtocontroltheamountoffluid
intotheairstream.Theopening betweenthenozzleseatandtipof thefluidneedlevalvedetermines
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theamountoffluidthatcanflow through.
Thefluidnozzleprovidesairflowtothetheaircap andhelpsmeterfluid.
Thefluidnozzle:
• workswiththefluidneedlevalue tometerfluidintotheairstream.
• formsaninternalseatforthefluid needlevalvetoshutoffthefluid flow.
• hasopenings.Thesizeof theopeningsdeterminesthe maximumamountoffluidthatcan bedelivered.
• providesairflowtotheaircap.
Fluidneedlesandnozzlescomematched.
Thefluidneedleandfluidnozzles arematchedtothespraygunandthe materialbeingsprayed.Theycannotbe interchangedwithotherneedlesand nozzles.Fluidneedlesandnozzlesmay benumericallyidentified.Thelargerthe number,thelargertheorifices.Larger numbersanddiameterorificesareusedto sprayhigherviscositymaterials.
Thebodyofthespraygunconnectsthepaintcup andhousesmanyoftheworkingparts.
Thebodyofthespraygunhouses,orhas attachedtoit,allthepartsthatmakeup aspraygun.Spraygunbodiesalsohave withinthemalloftheairpassagesand fluidpassages.
Spraygunsbodiesarecommonlymadeof aluminum.
HVLPspraygunshavelargerairpassages machinedthroughthespraygunbody. Thisistoaccommodatehighervolumesof compressedair.
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Thesprayguntriggeropensandclosestheairvalve andfluidvalve.
Thesprayguntriggerhastwosteps. Withthetriggeringofthefirststep, theairvalvesareopened,fillingthe chamberswithcompressedair.The secondtriggeringpullsthefluidneedle offofitsseatwhichallowstherefinish materialtoflowintothespraygunbody.
Shownisadisposableplasticpaintcupwithabuilt- instrainer.
Thepaintcup:
• ismountedtothespraygunbody. • maybeadisposableplastic
withabuilt-instrainer.Most strainersforwaterbornefinishes arerecommendedtobe125-200 microns.Refertothepaintmaker's
technicaldatasheettoverifythe correctstrainertypetouse.
• maybemetal,thoughitis recommendedtouseacoated orplasticpaintcupwithcertain materials,suchasetchingprimers andwaterborneproducts,asthey maycausedamagetouncoated metalpaintcups.Somerefinish materialsshouldnotbeleftina paintcupforextendedperiodsof time.
Thefluidcontrolisusedtoadjusttheamountof materialandatomization.
Thefluidcontroladjustmentaffectstwo basicfunctions.Thefluidcontrolcan be:
• adjustedtochangetheamountof materialreleasedfromthespray gun.
• usedtoadjusttheatomizationof thefluidexitingthespraygun.
Thefluidcontrolislocatedattherear ofaspraygun.Theadjustmentofthe fluidcontrolneedstobemadebefore therefinishtechnicianbeginsapplying anytypeofmaterial.Afluidcontrolset toolightwillcausepoorhiding,andan
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adjustmentthatistooheavymaycause runs.
Thefanadjustmentcanbelocatedindifferentareas dependingonthespraygunmaker.
Anotherimportantadjustmentofthe spraygunisthefanadjustment.Thefan adjustmentisusedtocontrolthesizeof thespraypattern.Thefanadjustmentcan beadjustedtoproduceaspraypattern thatisasmalldiametercircleoralong oblongpattern.
Alongwithchangingthephysicalspray pattern,thefanadjustmentcanalsoaffect theatomizationofthematerialbeing sprayed.
CleaningAndMaintenance
Spraygunwashersareusedtoevacuatesolvent fumesandcontaincleaningsolvent.
Whetherusingsolvent-borneor waterbornerefinishmaterials,always cleanthespraygunimmediatelyafter usewiththepaintmaker'srecommended solution.Thiswillhelpensurethatthe sprayguncontinuestooperateproperly andcontaminantsarenottransferredto otherrefinishingjobs.
Itemstokeepinmindwhenitcomesto cleaningasprayguninclude:
• donotimmerseandsoakinabath ofsolvent.Allowingaspraygun tobesoakedinsolventwillcause excessivestrippingofneeded lubrication.
• usingcompressedairtodrythe insideandoutsideofaspray gunthathasbeencleanedof waterbornematerials.
Aspraygunwasherisauniquecleaning toolfortherefinishtechnician.Spray gunwashersuseair-agitatedsolvent, whetheritbeforwaterborneorsolvent- bornerefinishmaterials,tocleanthe guns.Anenclosedspraygunwasher operatessimilartoadishwasher.Spray gunwashers:
• arefirerated. • mustbegroundedtoavoidsparks. • aregenerallypneumatically
operated. • mustbeassembledandused
accordingtolocalbuildingand firecodes.
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RefinishingEquipment(REF01e) 14
Spraygunwashercleaningsolvent isregulatedbylocalvolatileorganic compound(VOC)regulations.
RefertoVideo:CleaningASprayGun inthepresentation.Thisvideodiscusses cleaningaspraygun.
Spraygunspecificlubricantisneededtoproperly maintainaspraygun.
Whenmaintainingaspraygun, lubricationofmovingpartswillbe necessaryonaregularbasistohelp minimizewearandprolongthelifeofthe spraygun.Whenlubricatingaspraygun, usealubricantthat:
• isdesignedtobeusedonspray guns.
• iscompatiblewithrefinish materials.
• willnotcontaminatethespray gun.
Donotuseconventionaloilsuchas engineoil,transmissionfluid,WD-40, sprayorliquidsilicone,LiquidWrench,or airtooloilasthesewillcausedefectsin therefinishmaterials.
Therefinishtechnicianwillalsoneedto beabletoidentify:
• whatpartswearout,andhow oftentheyneedreplacement.
• whatpartsareavailableforthe specificspraygunused.
• ifthespraygunneedstobe returnedtothemanufacturerfor repair.
• ifarebuildkitisavailable,and whatpartsareincludedinthekit.
RefertoVideo:RebuildingASprayGun -Part1inthepresentation.Thisvideo discussesrebuildingaspraygun.
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RefertoVideo:RebuildingASprayGun -Part2inthepresentation.Thisvideo discussesrebuildingaspraygun.
HVLPSprayGunSetup
WhensettingupanHVLPspraygun:
• adjusttheinletpressure.Thespray gunmakerwillrecommenda specificinletpressureatthebase ofthespraygun.
• measuretheaircappressureand adjustasnecessaryforproper airflow.Toomuchortoolittle airflowcancauseproblemswhen applyingmaterial.
• aspecialgauge/capcanbeused formonitoringairpressureatthe aircap.Therearetwogaugeson
someairpressurecaps.These gaugesmeasureairpressureat theaircapearandnearthefluid nozzle.
Checkthematerialorspraygunmaker’s setupchartsfortheproperfluidneedle andnozzle.Belowarelinkstoseveralgun maker'ssetupcharts:
• AnestIwata • DeVilbiss • SataUSA
ShownisaSATAairregulator.
Whenadjustingairpressureattheinletof thespraygun,keepinmindthat:
• spraygunmakerswillstatea specificinletpressureatthebase ofthespraygun.
• theproperinletairpressurewill give10psiattheaircapwiththe fancontrolwideopen.
• asthefancontrolisclosed,theair cappressureincreases.
• airregulatorsadjusttheairsupply topressuresrequiredbythespray
gunmakerandforotherpower tools.Beginadjustingtheair pressureatthewallregulator andallowforpressuredropsif longairhosesarebeingused. Anairregulatoronthespraygun shouldbeusedtomakeminor adjustmentsonly.Ultimately, thepressurevalveatthespray gunshouldbeusedtomeasure inletpressure.Anairregulator maintainsaconstantairpressure andairvolume.Acheatervalve restrictsairflowandcreatesan unstableairpressureandair volume.Cheatervalvesshouldnot beusedwithsprayequipment.
Airpressureissetproperlyadjusted(left),too high(center),andnot enough air(right).
Whentestingforfluiddistribution:
• rotatetheaircapsothattheair horns,orears,arestraightup anddown.Thiswillproducea horizontalspraypattern.
• holdthespraygun8-10"fromthe surface.
• pullthetriggeruntiltherefinish materialbeginstorun.
• therunswillbeaboutthesame lengthifalladjustmentsare correct.
Ifthesidessagmore,theairpressureis toohighorthefanadjustmentknobisset toowide.
Ifthecentersagsmore,thereisnot enoughpatternair.Eitherturnoutthefan adjustmentknob,turninthefluidcontrol knob,orincreasetheairpressure.
Aspraypatternneedstobeuniformandequal.
Shownareseveralspraypatternproblems.
Toperformaqualityrefinish,thespray patternneedstobeuniformandequal.If thepatternisnotuniformwiththeamount ofmaterialthatisdeposited,thefinishwill haveapoorappearance.
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Abalancedspraypatternhasanequal amountofmaterialdepositedinthespray pattern.
Improperpatternswillshowheavyor lightspotsinthepattern.Apatternthatis depositingheavyonthetoporthebottom indicatesthatmaterialhasdriedaround theoutsideoftheaircap.Theaircapwill needtoberemoved,cleaned,andanew testpatternsprayed.Twoothertypesof spraypatternproblemsarea:
• crescent-shapedpatterns,caused bya restrictedairpassageinthe aircaphorn.
• figure8patterns,causedby atomizingairpressurethatis toohighfortheviscosityofthe materialbeingsprayed.
ModuleWrapUp
• thevarioustypes,designs,and partsofaspraygun.
• theimportanceofcleaningand maintainingaspraygun.
• howtosetupahighvolumelower pressure(HVLP)spraygun.
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Module2- CompressedAir
Module2-CompressedAirTextbook
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Learningobjectivesforthismodule include:
• explainingthetypeofcompressed airthatisrequiredforrefinishing.
• describinghowtousecompressed air.
Thepropersizeandtypeofaircompressoris necessaryforprovidingqualitycompressedair.
Compressedairforrefinishingneedsto beofahigherqualitythanthatusedfor ordinaryairtools.
Compressedairmustbecleananddry andnotcontainanycontaminants,such aswateroroilvapor.
Compressedairfiltersmaylookdifferentdepending onthefunctiontheyperform.
Tomaintainqualitycompressedairatthe spraybooth,the:
• filtersatornearthespraybooth mustbepurgedorinspectedona regularbasis.
• accumulationofcontaminants mustberemoved.Failureto maintainthefilterscanleadto paintdefects.
Filtersanddesiccantmaterialmaybeusedalongside eachother.
Airlinefiltersarecompressedairfilters thatareplacedinlineofthemainair supply.Theyaredesignedtocollectand removecontaminantsfromtheairsupply, suchasdebris,water,andoil.Examplesof airlinefiltersinclude:
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• filteredcentrifugalseparators, whichremovebulkliquidsfrom thecompressedair.
• coalescingoilremovalfilters, whichremoveoilaerosols containedwithinthefreshair breathingsystem.
• oilvaporadsorbingfilters,which removeoilvaporsandoilthat areinthegaseousstate.Thisis accomplishedthroughtwolayers ofactivatedcharcoal.
Fisheyesarecausedbyoiland/orwaterinthe compressedsprayingair.
Contaminatedcompressedsprayingair maycauserefinishmaterialtonotadhere toasurfaceand,dependingonthetypeof contamination,fisheyesmayoccur.
Whenapplyingafinishtoasurfacethere needstobecompleteandsolidadhesion. Failuretoattainproperadhesionmay resultinsmalltolargesectionsofrefinish materialliftingoreasilybeingremoved fromthesurface.
UsingCompressedAir
Connectairhoseinletstoregulatorsandshutoff valvesinsidethespraybooth.
Variablesthatmayleadtopressuredrops include:
• hoselength. • thetypeofregulatorsused. • thesizeofquick-disconnectsin
theairlines. • usinghoseslessthan3/8"inside
diameter.
Keephosesclean.Thiswillhelpairhoses lastlongerandreducecontaminationin thefinish.
Neveruseanairhoseforfreshairbreathingthatis notdesignedforthatspecificuse.
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Whenworkinginthesprayboothorinthe repairareaofthefacility,thereshouldbe separateairhosesusedforeacharea.The airhosesusedinthesprayboothshould notbeusedintheshop,andbreathingair hosesshouldhavedifferentstylequick- disconnectssotheycanonlyattachtothe breathingapparatus.
Freshairbreathinghoodsofferthemostprotection totheface,head,andneck.
Whileworkinginasprayenvironmentor withmaterialsthatproducehazardous vapors,theuseofcompressedair breathingequipmentmayberequired. Therearetwocommontypesof compressedairbreathingequipment. Theyare:
• freshairmasks,whichallowfresh airtobebreathedandofferno protectiontothefacialskin.
• freshairhoods,whichallow freshairtobebreathedandoffer completeprotectiontothefacial skin.
GradeDbreathingairhasrequirements thatmustbemetandmaintained.An audiblealarmmustbeheardinthe
spraybooth. Severalrequirementsfor gradeDbreathingairinclude:
• nooilvapors. • lessthan10partspermillion
(ppm)ofcarbonmonoxide(CO). • lessthan1,000ppmofcarbon
dioxide(CO2).
• thetypeofcompressedairthatis requiredforrefinishing
• howtousecompressedair.
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Module3-Spray Environment
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• describingthetypesof sprayboothscurrentlyinuse.
• identifyingthevariousadjustments thatcanbemadewithina spraybooth.
• explainingthedifferentcontrols andsettingsofaspraybooth.
• explaininghowtomaintaina spraybooth.
Theprepdeckmaybeusedforsandingorsprayinga limitedamountofmaterial.
Prepdecksmayappearsimilarin appearancetothatofaspraybooth. Thedifferencebeingisthataprepdeck typicallyhascurtainsandnotsolidwalls. Prepdecksmay:
• beusedasasandingstation. • allowrefinishmaterialstobe
applied. • beheated. • beusedforedgingparts. • beregulatedbylocalrules.
Somelocalornationalfirecodesmay regulatethetypesofdutiesthatmaybe performedinsideaprepdeck.
Asprayboothshouldbeclean,bright,andairtight.
Asprayboothprovides:
temperaturesforsprayingand baking.
• limitedexposuretohazardous chemicals.
• fireprotection. • color-correctedlightingforcolor
matching.
Shownarethethreedifferenttypesofspraybooths; downdraft(topleft),semi-downdraft(topright),and crossdraft(bottom).
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Thethreemostpopulartypesof sprayboothsinuseare:
• downdraft. • semi-downdraft. • crossdraft.
Adowndraftspraybooth:
• isdesignedtocontroloverspray removalanddustmoreeffectively whencomparedtoothertypesof sprayboothsavailabletoday.
• operatesbydrawingairinfrom theceilingandoutthroughthe floor.
• mayhavetheabilitytorecirculate heatedair.Recirculatingheated airallowsgreaterefficiencyofthe heatingsystem.
Airflowsdiagonallyinasemi-downdraftspraybooth.
Asemi-downdraftspraybooth:
• drawsairintothespraybooth fromventsabovethedoorsand evacuatestheairthroughtherear ofthespraybooth.
• allowsforcontrolofdust.Inthe eventthatthereisanydebrisin thespraybooth,insteadofitbeing drawnfromtheroofofthevehicle tothefloor,thedebrisismoved acrossthelengthofthevehicle. Thisallowsmoresurfaceareafor thedebristocontact.
Airflowsthisdirectioninacrossdraftspraybooth.
Acrossdraftspraybooth:
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• drawsairintothesprayboothfrom filtersinthedoorsandevacuates theairthroughfiltersintherear cornersofthespraybooth.
• allowsforcontrolofdust.Inthe eventthatthereisanydebris inthespraybooth,thedebrisis movedacrossthelengthofthe vehicle.Thisallowsgreatersurface areaforthedebristocontact. Thecrossdraftsprayboothdirects mostofitsairflowalongthesides ofthevehicle.Thisisbecause theexhaustfiltersareprimarily locatedattherearcornersofthe spraybooth.
SprayboothAdjustments
Theinternalsprayboothtemperaturecanbeadjusted atthecontrolpanel.
Sprayboothshaveavarietyofadjustments thatcanbeperformed.Theseadjustments caninclude:
• settingtoaspecifictemperature. • airpressure.Thismayinclude
increasingordecreasingthe amountofairenteringandexiting thespraybooth.
• adjustmenttoonespecific temperatureandpressuresetting foraspecifictypeofmaterial.
Theamountofairflowthroughthesprayboothcan affecttheoutcomeoftherefinish.
Toproperlytesttheamountofairflowing throughaspraybooth,theuseofa Magnahelicoramanometerisrequired. ThefunctionofaMagnahelicisto measurethepressureorvacuumina spraybooth.
Toomuchpressureinthesprayboothis called“positivepressure.”Thisoccurs whenmoreairisenteringthespraybooth thanisexiting.
Toomuchvacuuminthesprayboothis called“negativepressure.”Thisoccurs whenmoreairisexitingthespraybooth thanisentering.
Prepdecks,likespraybooths,maybeable tobebalancedbywatchingthecurtains. Toomuchpressurecausesthecurtainsto pushout.Toolittlepressurecausesthe curtainstodrawintotheprepdeck.
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Toolittleairflowmaycausepoormaterialtransfer.
Settingthesprayboothtocreateavacuum ornegativepressuremaycause:
• avacuumwithinthespraybooth. • dirttobedrawninfromoutside
thespraybooth. • impropermaterialtransfer.
Sprayboothpressureismonitoredwiththe useofaMagnahelicormanometer.
Toomuchincomingairflowwillnotevacuatedust andoverspray.
Positivepressureoccurswhenmoreair isenteringthespraybooththanisexiting. Settingthesprayboothtocreateapositive pressuremaycause:
• thesprayboothtobecome pressurizedandforcerefinish materialintotheshop environment.
• dirttobeheldoutsideofthe spraybooth.Thishappensbyair pressureseepingpastandthrough sealsandgaskets.
• overspraytonotberemovedfrom thespraybooth.Thisiscausedby insufficientexitingairflow.
Dirtyfilterswillrestrictairflow.
Restrictedairflowormovementthrougha sprayboothmayindicatethat:
• therearedirty,restrictedfilters. • thesprayboothbafflesarenot
functioningproperly. • refinishingisperformedinone
areaofthespraybooth.
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Sprayboothfiltersshouldbereplacedonaregular schedule.
Sprayboothfiltersrequirereplacement atvariousintervalsdependingonthe amountofhoursthesprayboothfilters havebeenexposedtopaintanddebris. Thereplacementofsprayboothfiltersare importantbecause:
• asprayboothshouldnotbe balanceduntilafterthefiltershave beenreplaced.
• cleansprayboothfiltersaidin producingaqualityrefinish.
• insomegeographicalareas thebuildupofdebrismaybe consideredahazardousmaterial andmayrequirespecialdisposal oftheusedfilters.
Allsprayboothfiltersshouldbecheckedfor replacementonaregularbasis.
Thereareavarietyoffiltersusedina downdraftspraybooth,includingthe:
• intakefilters. • pre-filters. • ceilingfilters. • in-floorfilters. • recirculationfilters.
ControlsAndSettingsOfASpraybooth
Sprayboothtemperaturecanbeadjustedtomatch refinishmaterialrequirements.
Thethreemaincyclesofaspraybooth includethe:
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• spraycycle,whichcontrolsthe sprayboothconditionswhilethe technicianisapplyingrefinish materials.
• purgecycle,whichevacuates excessoversprayanddebrisfrom thesprayboothbeforebaking.
• bakecycle,whichaidsinthe dryingandcuringoftherefinish material.
Thesecyclesmaybeonacontrol panelthathastobereseteverytimea changeoccurs,ortheymaybeableto bepreprogrammedintothespraybooth controlcenterfordifferenttypesof materials.
Thesprayboothtemperatureisdisplayedduringthe spraycycle.
Thespraycycleallowstherefinish techniciantoadjustandmaintainproper sprayboothtemperatures.Withtheability tomanipulatethetemperatureateach stagearefinishmaterialisapplied,the refinishtechnicianshouldbeableto attaintopqualityresults.
Thesprayboothtemperatureandtimeleftis displayedduringthepurgecycle.
Thepurgecycleallowstherefinish techniciantimebetweenthespraycycle andthebakecycletoevacuatesolvents, moisture,debris,andothercontaminants withinthespraybooth.Withtheabilityto manipulatethisenvironment,therefinish technicianshouldbeabletoattaintop qualityresults.
Thesprayboothtemperatureandtimeleftis displayedduringthebakecycle.
Thebakecycle,whichfollowsthepurge cycle,allowstherefinishtechnicianto acceleratethedryingtimeofrefinish materials.
Althoughtherefinishtechnicianhas theabilitytodryandcurerefinish materialsfasterthanjustairdrying,the
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technicianstillneedstorealizethatthere arevariablesthatcancausepoorresults ifthepaintmaker’sguidelinesarenot followed.
VehicleProtection
Vehiclesthatusecompressednaturalgas shouldhavethetanksremovedbeforethe vehicleismovedintoaspraybooth.
Illustratediswhatoccursduringthedryingand curingprocess.
Afterrefinishmaterialsareapplied,there aretwoprocessesthatoccur.Thereisthe stateof:
• dryingwhentheevaporationof solventsandliquidsareremoved fromthematerial.
• curingwhenachemicalchange occurswithintherefinishmaterial.
Surfacetemperaturecanbemeasuredusinga noncontactsurfacethermometer.
Availablesurfacetemperature thermometersinclude:
• magneticandpaperthermometers, whichcanbeplacednearthearea beingheated.
• noncontacttypethermometers, whichcanbeusedfroma distance.
Somesprayboothsrecirculateheatedair.
Sprayboothburnerefficiencyhasto dowiththedesignofthespraybooth andtheabilitytorecirculateheated air.Somesprayboothsaredesignedto recirculatetheheatedairduringthebake cycle.Thiskeepstheburnersfrombeing
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overworked.Aspraybooththatisdesigned toconstantlyheattheoutsideairwithout reclaiminganyoftheheatedaircauses inefficientheating.
Shownisaportableinfraredlamp(topleft),hand heldmulitpliers(bottomleft),andventuriblowers (right).
Whendryingorcuringtheappliedfinish, therearebothportableandpermanent dryingandcuringtools.Portabletools include:
• infrared(IR)heaters,whichusea typeoflamptocreatetheheating effect.
• handheldmultipliers,usedwith waterbornematerials.
Permanentdryingandcuringtoolsmay be:
• venturiblowers,alsomountedon thesprayboothwalls.
• convectionheat,whichisheated airforcedfromtheceilingtothe floor.
AportableIRheatingunitcanbemovedaroundthe shopforconvenience.
PermanentandportableIRheatingunits operatebyusingshortandmediumwave lengthsfromthelightspectrum.
Thesewavestravelthroughtheairheating onlythesolidobjecttheycontact.As thewavelengthspenetratetherefnished surface,theentirefilmthicknessisheated, thusaidinginthereleaseofsolventsand dryingofthematerial.
Venturiblowersareusedtoremovewaterfrom waterbornematerials.
Unheatedsprayboothairisblownthrough smallventuri-styleblowers.Thistypeof blower:
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 35
• maybeportableorpermanently mountedinthespraybooth.
• isusedtoremovethemoisture fromwaterbornematerials.
Sprayboothburnersarelocatedontheairintakeside ofthespraybooth.
Theconvectionheatingsystem operatessimilartoanoven.Thereare burnerslocatedontheairintakeofthe spraybooth.Beforetheairentersthe spraybooth,itisheatedbytheburners, andthewarmairisdirectedacrossthe vehicle.
SprayboothMaintenance
Shownaresprayboothwallsthathavespraybooth wrapapplied.
Toensurethataqualityrefinishis obtained,therearecertainspraybooth cleaningproceduresthatneedtobe performedonaregularbasis.These proceduresinclude:
• vacuumingthesprayboothfloor. • sandblastingthefloorgratesto
removeexcessiveoverspray. • wipingdownthedoorsealsto
preventdirtfromgettingintothe spraybooth.
• wipingdownthewallstokeep themwhiteandfreeofdebris.
• applyingsprayboothmaskingto thewallsofthespraybooth.This willhelpeliminateoversprayfrom stickingtothesprayboothwalls.
• applyingsprayboothwrap, referredtoasDirtTrapby3M, tothewallsandfloorofthe spraybooth.Thisimprovesthe refinishqualitybytrapping airbornecontaminants.
Referto“Video:BoothWrap-3MDirt TrapInstallation”inthepresentation.This videodiscusseshowtoinstall3MDirt Trap.
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 36
Specialdiagnostictoolsmayberequiredto determinesprayboothproblems.
Whenasprayboothdoesnotoperate properly,thereisspecializeddiagnostic equipmentthatmaybeusedtodetermine thecauseoftheproblem.Thesetools includea:
• maintenancechecklist. • velometer. • smokegenerator. • particlecounter. • lightmeter.
Avelometermeasurestheexchangeofairthrougha spraybooth.
Velometersareusedwhentheremaybe aconcernaboutairflowproblemswithin aspraybooth.Thesemetersmeasure
theamountofairflowingthroughthe spraybooth.
Asmokegeneratorisusedtoshowhowairflowis directedoverthesurfaceofavehicle.
Smokegeneratorsareusedtoobservethe amountanddirectionofairflowthrough aspraybooth.Thetechnicianusesthe smokegeneratortoemitsmokearound avehiclepositionedinasprayboothto determinethepaththesmoketakestothe exhaustfilters.
Shownisaparticulatecounter.
Themainfunctionoftheparticulate counteristo:
• measuretheamountofdebrisin theair.
• determineiftheamountofdebris isexcessive.
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RefinishingEquipment(REF01e) 37
• helpdeterminereplacement intervalsforthesprayboothfilters.
Sprayboothlightingshouldbeasclosetonatural daylightaspossible.
Sprayboothlightinghasthreeimportant variables.Thesevariablesinclude:
• colortemperature.Color temperatureismeasuredinKelvin.
• colorrenderingindex,orCRI.The CRIshouldbegreaterthan93%.
• candlepower.Candlepowershould be5-10kfootcandles.
Thetechnicianisusingalightmeter.
Whileusingalightmeter,thetechnician shouldbeableto:
• determinethecurrentcolor renderingindex(CRI)ofthe sprayboothlighting.TheCRIis howclosetonaturaldaylightthe lightingis.
• determinethecurrent candlepowerofthespraybooth lighting.
Ifanyofthesemeasurementsshowto bebelowtheproperlevel,theglass lensesshouldbecleanedandthe levelsrechecked.Ifstillincorrect,bulb replacementisrequired.
Sprayboothlightbulbsshouldbereplacedona regularbasis.
Sprayboothlightsshouldbereplaced onaregularschedule.Failuretoreplace sprayboothlightsmaycauseproblems, suchas:
• bulbschangingcolorwithage. • bulbsburningoutatvarioustimes
duringsprayboothoperationand use.
• poorcolormatches.
• thetypesofsprayboothscurrently inuse.
• thevariousadjustmentsthatcan bemadewithinaspraybooth.
• thedifferentcontrolsandsettings ofaspraybooth.
• howtomaintainaspraybooth.
Module4-Mixing Equipment
Module4-MixingEquipmentTextbook
RefinishingEquipment(REF01e) 41
MixingRoomAndTools
• explainingmixingratios. • describingthedifferencebetween
cottonandnylonpaintstrainers. • describinghowandwheremixing
sticksandcupsareused. • explaininghowtodisposeof
excessrefinishmaterials.
Mixingroomscontainthematerialsandequipment forpreparingrefinishmaterials.
Thepaintmixingroomisdesignedto:
• beself-ventilating. • containanyspillsthatoccur. • meetlocalfirecodes. • begroundedtoavoidsparksand
explosions. • haveexplosion-proofwiring.
Differentamountsofmaterialareneededfor differentmixingratios.
Mostproductsusedforrefinishingin theautomotivecollisionrepairindustry requirethattheybemixedorreduced. Dependingonthetypeofpaintsystem therecanbedifferentmixingratios used.
Someofthemixingratiosmayinclude:
• 3:1=3partsto1part.A3:1ratio istakingpartsoftwoproductsand mixingthemtogether.Examples ofthisaremixing: 3ozofone primerand1ozofhardeneror 10.5ozofoneprimerand3.5oz ofhardener.
• 3:1:1=3partsto1partto1 part.A3:1:1ratioistaking threeproductsandmixingthem together.Examplesofthisare mixing: 3 ozofprimerand1oz ofhardenerand1ozofreducer or10.5ozofprimerand3.5ozof hardenerwith3.5ozofreducer.
• 1:1:10-20%=1partto1part +10-20%ofapart.A1:1:10- 20%ratioistakingequalpartsof twoproductsandmixingthem together.Thenbydoingamath
Module4-MixingEquipmentTextbook
RefinishingEquipment(REF01e) 42
equation,figureoutfromthe mixedproducthowmuchofthe mixedproductis10-20%,then addthat10-20%quantityofthe thirdproduct.Examplesofthisare mixing:1ozofpaintand1ozof reducerandthen0.1-0.2ozof atomizingagentor15ozofpaint and15ozofreducerandthen1.5 -3.0ozofanatomizingagent.
Mixingcups,viscositycups,paintfilters,andmixing sticksareallimportanttoolsneededtohelpcreatea qualityrefinish.
Thetoolsthatmaybeneededwhen mixingrefinishmaterialsinclude:
• mixingratiocupsandsticks, whichareusedforobtainingthe properblendofmaterials.
• alint-freestrainer.Strainersshould betestedforresistancetosolvents andwater.Soakthestrainerfor acoupleminutesinwaterand alsoinsolvent.Debriscould endupinthepaintcupifthere isanychangetothestrainer. Strainersalsoshouldhavenylon meshinsteadofcotton.Thisis becausecottonhaslintthatcanbe depositedintothepaintcup.
• aviscositycup.Aviscositycupis usedtogaugehowfastamaterial canpassthroughagivensize orifice.Thiswillthendetermine thespraygunsetupthatisneeded.
Mixingratiocupshavegraduatedscalesontheir sides.
Mixingratiocupsareusedformixing paint,reducer,andhardener.Mixingratio cupsmayhavegraduatedscalesonthe sidesofthecuptoaidinpropermixtures. Differentmixingratiocupsmayhave:
• ascaleformixing.
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RefinishingEquipment(REF01e) 43
• parallelsides.Thebottomof themixingratiocupshouldbe perpendiculartothesidestohelp ensurepropermixingisattained.
• agraduatedscaleforcupsthat havenonparallelsides.
Mixingstickstypicallyhavespecificmixingratios embossedonthemforeaseofuseandreuse.
Mixingsticksareavailablebymost paintmakers.Paintmakersthatoffer mixingstickswillhavemixingsticks neededtosupporttheirmixingformula requirements.Whenusingmixingsticks, guidelinesmustbefollowed.Whenusing amixingstick:
• placethestickinacontainerand followtheappropriatescale.
• donotsetthematanangle. • thescalesmustbefollowed
exactly. • usecontainerswithnontapered
sides. • thecorrectstickfromthepaint
makerneedstobeused.Each paintmakerhastheirownsetof mixingsticksmadeespeciallyfor theirratios.
Viscositycupsareusedtomeasurethethicknessof therefinishmaterial.
Viscositycupsareusedtomeasurethe rateofmaterialflow.Therearedifferent typesofviscositycups.Besuretouse thecorrectcupfortheapplication requirements.Differenttypeofviscosity cupsmaybeabletobeinterchanged insomeapplications.Threecommon viscositycupsusedincludetheZahn, Ford,andDincup.
Shownisasolventrecycler.
Usedmaterialcontainersaredesigned forholdingsmallamountsofwastefora shortperiodoftime.Thesecontainersmay also:
Module4-MixingEquipmentTextbook
RefinishingEquipment(REF01e) 44
• holdusedmaterialuntilplacing intolargerholdingdrums.
Whenusingausedsolventcontainer,itis asafepracticetouseasystemthathasa coverandkeepsfumesfromescaping.If anuncoveredcontainerisused,thefumes cancauseafireandhealthhazard.
ModuleWrapUp
• mixingratios. • thedifferencebetweencottonand
nylonpaintstrainers. • howandwheremixingsticksand
cupsmaybeused. • thedisposalofexcessrefinish
materials.
Spraybooth Maintenance
RefinishingEquipment(REF01e)Textbook
Module1-Spray Guns
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 7
Learningobjectivesforthismodule include:
• describingthevarioustypes, designs,andpartsofaspraygun.
• explainingtheimportanceof cleaningandmaintainingaspray gun.
• describinghowtosetupahigh volumelowpressure(HVLP)spray gun.
Gravityfeedspraygunsarecommontypesoftools usedforrefinishing.
Spraygunsusedforrefinishingmaybe differentdesigns.Someoftheseare:
• highpressure(HP).AnHPspray gunuseshighpressure,low volume air.Theinletairpressures foranHPrangefrom70to90 poundspersquareinch(psi).This typeofspraygunmayalsobe referredtoasconventional.HP spraygunsareconsideredold technology.
• highvolumelowpressure(HVLP). AnHVLPspraygunoperatesby
highvolumeandlowpressureof airpassingthroughthespraygun. Theinletairpressureisabout45 psiwithanaircap pressureof10 psiorless.
• reducedpressure(RP).An RPspraygunusesareduced inlet pressureof32psithatallows optimizedhighpressuretoacheive transferefficiencyabove65%, eventhoughthegundoesnot have10psiorlessattheaircap. Thistypeofspraygunisprimarily usedforhighsolidclearcoats, asitaidsintheatomization andevaporationofsolventsand reducerstoallowforanimproved transferofmaterial.
Lowvolumelowpressure(LVLP)spray gunshavelimiteduseandavailability.
Theamountofairpressurethatis producedbyanaircompressoris measuredinpsi.Cubicfeetperminute (cfm)isthevolumeofairdeliveredthat isrequiredforatooltooperateproperly. Smalleraircompressorsmaynotbeable toproducethehighairvolumerequired forHVLPsprayguns.Mostairtoolsused inarepairfacilityrequirelesscfmthan thetoolsusedforrefinishing.Anexample ofthisistheDynalocke dual-action(DA) sanderwhichrequires3cfm,whereasan HVLPspraygunisupwardsof25cfm.
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 8
ShownareHVLPgravity(left)andsiphon(right) feedsprayguns.
Spraygunsmaybe:
• gravityfeed.Gravityfeedspray gunsoperatebythepaintcup beinglocatedabovethespray gunbody.Fluidwillflowoutof agravityfeedspraygunwhen thereisnoairpressureandthe triggerispulled.Thisisbecause materialmovesthroughthespray gunbygravitationalforceandnot vacuum.
• siphonfeed.Asiphonfeedspray gunhasthepaintcuplocated belowthespraygunbody.The materialisdrawnoutofthespray gunbyvacuumcreatedbytheair cap.Atmosphericpressureinside thepaintcupforcesthematerial upthroughthespraygunbody andoutofthefluidneedle.
Pressurefeedsprayguns,thoughcommon atonetimeintheindustryforspraying refinishmaterials,arenowtypically usedtoapplychip-resistantcoatingsand corrosionprotectionmaterials.Apressure feedspraygunoperatesbypressurizing
thecupwhichaidesinallowinghigher viscositymaterialstobeatomized.
HVLPallowsformorecontroloftherefinishmaterial, whichaidesintransferefficiency.
Transferefficiencyistheamountof materialasprayguncandepositon asurface.Thematerialthatisnoton theintendedsurfaceisconsidered overspray.
AnadvantageofusinganHVLPisthatthe useoflowerpressuresallowsformore controlofthematerialbeingsprayed. ThetransferefficiencyofanHVLPspray gunistypically65%orbetter.Thiscan beaffectedbymanyvariables,including spraytechnique.Severalwaystoincrease transferefficiencyaretouse:
• therecommendedspraygunsetup forfluidneedle,fluidnozzleand aircapselection.
• asmallerspraypattern.Thiskeeps therefinishmaterialfocusedon thepanel.
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 9
Partsofaspraygunthatmayrequire frequentcleaningandadjustmentinclude the:
1. aircap,whichislocatedonthe topofthespraygun.Theairports ontheaircapdirectairflowpast thefluidnozzle.Astheairpasses bythefluidnozzle,avacuumis createdandthepaintalsogets atomized.
2. fluidnozzle,whichismatchedto thefluidneedleandmustbekept insets.
3. fluidneedle,whichmovesinand outofthespraygunandcanbe adjustedtoregulatetheamountof fluiddelivered.
4. spraygunbody,whichhouses,or hasattachedtoit,alloftheparts thatmakeupaspraygun.Spray gunbodiesalsohavewithinthem alloftheairandfluidpassages.
5. trigger,whichisthecontrolforthe fluidneedlevalveandairvalve.
6. paintcup,whichmaybe locatedinavarietyofpositions. Dependingonthetypeofspray gunbeingusedthepaintcup couldbelocatedabove,below,or attachedbyahose.
7. fluidcontrolknob.Adjusting thefluidcontrolonaspraygun changestheamountoffluidthat isreleasedoutofthespraygun. Thespraypatterncanbeadjusted fromalightdustingtoadeposit ratethatwillcauseruns.
8. fanadjustmentknob,whichis usedtochangethespraypattern ofthespraygun.Thespraypattern
canbeadjustedfromasmall circletoanoblongspraypattern.
Refertothe“Animation:GravityFeed SprayGun”inthepresentation.This animationshowshowrefinishmaterial andcompressedairflowthroughaspray gun.
Shownarethethreedifferentairpassageswithinthe aircap.
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 10
Shownareseveraldifferenttypesofaircaps.
Anaircaphaspassagesthatdirectairpast thefluidneedle.Thesepassagesarethe:
• centerhole. • auxiliaryholes. • airhornholes.
Thetypeofaircapmayalsoaffectthe amountof:
• fluidflowthroughthespraygun. • airpressureneeded.
Thefullatomizationofrefinishmaterialoccursin threestages.
Thesepassageswithintheaircaphelp achievefullatomizationinthreestages. Duringthe:
• firststage,arushofairfromthe centerholecreatesavacuum at thefluidtip.Asairisdirected acrossthefluidpassages,a pressuredifferenceoccurs.Thisis duetothecreationofaventurior vacuum.Therefinishmaterialis pulledinbythevacuumandair turbulencestartstobreakupthe refinishmaterial.
• secondstage,partiallyatomized refinishmaterial ishitbyanair streamfromtheauxiliaryholes andtherefinishmaterialisfurther atomized.
• thirdstage,airfromtheairhorn holeshitstheatomizedrefinish materialandcausesittoformthe spraypattern.
Shownisafluidneedle.
Thefluidneedleis:
• openedandclosedbythetrigger. • usedtocontroltheamountoffluid
intotheairstream.Theopening betweenthenozzleseatandtipof thefluidneedlevalvedetermines
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 11
theamountoffluidthatcanflow through.
Thefluidnozzleprovidesairflowtothetheaircap andhelpsmeterfluid.
Thefluidnozzle:
• workswiththefluidneedlevalue tometerfluidintotheairstream.
• formsaninternalseatforthefluid needlevalvetoshutoffthefluid flow.
• hasopenings.Thesizeof theopeningsdeterminesthe maximumamountoffluidthatcan bedelivered.
• providesairflowtotheaircap.
Fluidneedlesandnozzlescomematched.
Thefluidneedleandfluidnozzles arematchedtothespraygunandthe materialbeingsprayed.Theycannotbe interchangedwithotherneedlesand nozzles.Fluidneedlesandnozzlesmay benumericallyidentified.Thelargerthe number,thelargertheorifices.Larger numbersanddiameterorificesareusedto sprayhigherviscositymaterials.
Thebodyofthespraygunconnectsthepaintcup andhousesmanyoftheworkingparts.
Thebodyofthespraygunhouses,orhas attachedtoit,allthepartsthatmakeup aspraygun.Spraygunbodiesalsohave withinthemalloftheairpassagesand fluidpassages.
Spraygunsbodiesarecommonlymadeof aluminum.
HVLPspraygunshavelargerairpassages machinedthroughthespraygunbody. Thisistoaccommodatehighervolumesof compressedair.
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 12
Thesprayguntriggeropensandclosestheairvalve andfluidvalve.
Thesprayguntriggerhastwosteps. Withthetriggeringofthefirststep, theairvalvesareopened,fillingthe chamberswithcompressedair.The secondtriggeringpullsthefluidneedle offofitsseatwhichallowstherefinish materialtoflowintothespraygunbody.
Shownisadisposableplasticpaintcupwithabuilt- instrainer.
Thepaintcup:
• ismountedtothespraygunbody. • maybeadisposableplastic
withabuilt-instrainer.Most strainersforwaterbornefinishes arerecommendedtobe125-200 microns.Refertothepaintmaker's
technicaldatasheettoverifythe correctstrainertypetouse.
• maybemetal,thoughitis recommendedtouseacoated orplasticpaintcupwithcertain materials,suchasetchingprimers andwaterborneproducts,asthey maycausedamagetouncoated metalpaintcups.Somerefinish materialsshouldnotbeleftina paintcupforextendedperiodsof time.
Thefluidcontrolisusedtoadjusttheamountof materialandatomization.
Thefluidcontroladjustmentaffectstwo basicfunctions.Thefluidcontrolcan be:
• adjustedtochangetheamountof materialreleasedfromthespray gun.
• usedtoadjusttheatomizationof thefluidexitingthespraygun.
Thefluidcontrolislocatedattherear ofaspraygun.Theadjustmentofthe fluidcontrolneedstobemadebefore therefinishtechnicianbeginsapplying anytypeofmaterial.Afluidcontrolset toolightwillcausepoorhiding,andan
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 13
adjustmentthatistooheavymaycause runs.
Thefanadjustmentcanbelocatedindifferentareas dependingonthespraygunmaker.
Anotherimportantadjustmentofthe spraygunisthefanadjustment.Thefan adjustmentisusedtocontrolthesizeof thespraypattern.Thefanadjustmentcan beadjustedtoproduceaspraypattern thatisasmalldiametercircleoralong oblongpattern.
Alongwithchangingthephysicalspray pattern,thefanadjustmentcanalsoaffect theatomizationofthematerialbeing sprayed.
CleaningAndMaintenance
Spraygunwashersareusedtoevacuatesolvent fumesandcontaincleaningsolvent.
Whetherusingsolvent-borneor waterbornerefinishmaterials,always cleanthespraygunimmediatelyafter usewiththepaintmaker'srecommended solution.Thiswillhelpensurethatthe sprayguncontinuestooperateproperly andcontaminantsarenottransferredto otherrefinishingjobs.
Itemstokeepinmindwhenitcomesto cleaningasprayguninclude:
• donotimmerseandsoakinabath ofsolvent.Allowingaspraygun tobesoakedinsolventwillcause excessivestrippingofneeded lubrication.
• usingcompressedairtodrythe insideandoutsideofaspray gunthathasbeencleanedof waterbornematerials.
Aspraygunwasherisauniquecleaning toolfortherefinishtechnician.Spray gunwashersuseair-agitatedsolvent, whetheritbeforwaterborneorsolvent- bornerefinishmaterials,tocleanthe guns.Anenclosedspraygunwasher operatessimilartoadishwasher.Spray gunwashers:
• arefirerated. • mustbegroundedtoavoidsparks. • aregenerallypneumatically
operated. • mustbeassembledandused
accordingtolocalbuildingand firecodes.
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 14
Spraygunwashercleaningsolvent isregulatedbylocalvolatileorganic compound(VOC)regulations.
RefertoVideo:CleaningASprayGun inthepresentation.Thisvideodiscusses cleaningaspraygun.
Spraygunspecificlubricantisneededtoproperly maintainaspraygun.
Whenmaintainingaspraygun, lubricationofmovingpartswillbe necessaryonaregularbasistohelp minimizewearandprolongthelifeofthe spraygun.Whenlubricatingaspraygun, usealubricantthat:
• isdesignedtobeusedonspray guns.
• iscompatiblewithrefinish materials.
• willnotcontaminatethespray gun.
Donotuseconventionaloilsuchas engineoil,transmissionfluid,WD-40, sprayorliquidsilicone,LiquidWrench,or airtooloilasthesewillcausedefectsin therefinishmaterials.
Therefinishtechnicianwillalsoneedto beabletoidentify:
• whatpartswearout,andhow oftentheyneedreplacement.
• whatpartsareavailableforthe specificspraygunused.
• ifthespraygunneedstobe returnedtothemanufacturerfor repair.
• ifarebuildkitisavailable,and whatpartsareincludedinthekit.
RefertoVideo:RebuildingASprayGun -Part1inthepresentation.Thisvideo discussesrebuildingaspraygun.
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 15
RefertoVideo:RebuildingASprayGun -Part2inthepresentation.Thisvideo discussesrebuildingaspraygun.
HVLPSprayGunSetup
WhensettingupanHVLPspraygun:
• adjusttheinletpressure.Thespray gunmakerwillrecommenda specificinletpressureatthebase ofthespraygun.
• measuretheaircappressureand adjustasnecessaryforproper airflow.Toomuchortoolittle airflowcancauseproblemswhen applyingmaterial.
• aspecialgauge/capcanbeused formonitoringairpressureatthe aircap.Therearetwogaugeson
someairpressurecaps.These gaugesmeasureairpressureat theaircapearandnearthefluid nozzle.
Checkthematerialorspraygunmaker’s setupchartsfortheproperfluidneedle andnozzle.Belowarelinkstoseveralgun maker'ssetupcharts:
• AnestIwata • DeVilbiss • SataUSA
ShownisaSATAairregulator.
Whenadjustingairpressureattheinletof thespraygun,keepinmindthat:
• spraygunmakerswillstatea specificinletpressureatthebase ofthespraygun.
• theproperinletairpressurewill give10psiattheaircapwiththe fancontrolwideopen.
• asthefancontrolisclosed,theair cappressureincreases.
• airregulatorsadjusttheairsupply topressuresrequiredbythespray
gunmakerandforotherpower tools.Beginadjustingtheair pressureatthewallregulator andallowforpressuredropsif longairhosesarebeingused. Anairregulatoronthespraygun shouldbeusedtomakeminor adjustmentsonly.Ultimately, thepressurevalveatthespray gunshouldbeusedtomeasure inletpressure.Anairregulator maintainsaconstantairpressure andairvolume.Acheatervalve restrictsairflowandcreatesan unstableairpressureandair volume.Cheatervalvesshouldnot beusedwithsprayequipment.
Airpressureissetproperlyadjusted(left),too high(center),andnot enough air(right).
Whentestingforfluiddistribution:
• rotatetheaircapsothattheair horns,orears,arestraightup anddown.Thiswillproducea horizontalspraypattern.
• holdthespraygun8-10"fromthe surface.
• pullthetriggeruntiltherefinish materialbeginstorun.
• therunswillbeaboutthesame lengthifalladjustmentsare correct.
Ifthesidessagmore,theairpressureis toohighorthefanadjustmentknobisset toowide.
Ifthecentersagsmore,thereisnot enoughpatternair.Eitherturnoutthefan adjustmentknob,turninthefluidcontrol knob,orincreasetheairpressure.
Aspraypatternneedstobeuniformandequal.
Shownareseveralspraypatternproblems.
Toperformaqualityrefinish,thespray patternneedstobeuniformandequal.If thepatternisnotuniformwiththeamount ofmaterialthatisdeposited,thefinishwill haveapoorappearance.
Module1-SprayGunsTextbook
RefinishingEquipment(REF01e) 17
Abalancedspraypatternhasanequal amountofmaterialdepositedinthespray pattern.
Improperpatternswillshowheavyor lightspotsinthepattern.Apatternthatis depositingheavyonthetoporthebottom indicatesthatmaterialhasdriedaround theoutsideoftheaircap.Theaircapwill needtoberemoved,cleaned,andanew testpatternsprayed.Twoothertypesof spraypatternproblemsarea:
• crescent-shapedpatterns,caused bya restrictedairpassageinthe aircaphorn.
• figure8patterns,causedby atomizingairpressurethatis toohighfortheviscosityofthe materialbeingsprayed.
ModuleWrapUp
• thevarioustypes,designs,and partsofaspraygun.
• theimportanceofcleaningand maintainingaspraygun.
• howtosetupahighvolumelower pressure(HVLP)spraygun.
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Module2- CompressedAir
Module2-CompressedAirTextbook
RefinishingEquipment(REF01e) 21
Learningobjectivesforthismodule include:
• explainingthetypeofcompressed airthatisrequiredforrefinishing.
• describinghowtousecompressed air.
Thepropersizeandtypeofaircompressoris necessaryforprovidingqualitycompressedair.
Compressedairforrefinishingneedsto beofahigherqualitythanthatusedfor ordinaryairtools.
Compressedairmustbecleananddry andnotcontainanycontaminants,such aswateroroilvapor.
Compressedairfiltersmaylookdifferentdepending onthefunctiontheyperform.
Tomaintainqualitycompressedairatthe spraybooth,the:
• filtersatornearthespraybooth mustbepurgedorinspectedona regularbasis.
• accumulationofcontaminants mustberemoved.Failureto maintainthefilterscanleadto paintdefects.
Filtersanddesiccantmaterialmaybeusedalongside eachother.
Airlinefiltersarecompressedairfilters thatareplacedinlineofthemainair supply.Theyaredesignedtocollectand removecontaminantsfromtheairsupply, suchasdebris,water,andoil.Examplesof airlinefiltersinclude:
Module2-CompressedAirTextbook
RefinishingEquipment(REF01e) 22
• filteredcentrifugalseparators, whichremovebulkliquidsfrom thecompressedair.
• coalescingoilremovalfilters, whichremoveoilaerosols containedwithinthefreshair breathingsystem.
• oilvaporadsorbingfilters,which removeoilvaporsandoilthat areinthegaseousstate.Thisis accomplishedthroughtwolayers ofactivatedcharcoal.
Fisheyesarecausedbyoiland/orwaterinthe compressedsprayingair.
Contaminatedcompressedsprayingair maycauserefinishmaterialtonotadhere toasurfaceand,dependingonthetypeof contamination,fisheyesmayoccur.
Whenapplyingafinishtoasurfacethere needstobecompleteandsolidadhesion. Failuretoattainproperadhesionmay resultinsmalltolargesectionsofrefinish materialliftingoreasilybeingremoved fromthesurface.
UsingCompressedAir
Connectairhoseinletstoregulatorsandshutoff valvesinsidethespraybooth.
Variablesthatmayleadtopressuredrops include:
• hoselength. • thetypeofregulatorsused. • thesizeofquick-disconnectsin
theairlines. • usinghoseslessthan3/8"inside
diameter.
Keephosesclean.Thiswillhelpairhoses lastlongerandreducecontaminationin thefinish.
Neveruseanairhoseforfreshairbreathingthatis notdesignedforthatspecificuse.
Module2-CompressedAirTextbook
RefinishingEquipment(REF01e) 23
Whenworkinginthesprayboothorinthe repairareaofthefacility,thereshouldbe separateairhosesusedforeacharea.The airhosesusedinthesprayboothshould notbeusedintheshop,andbreathingair hosesshouldhavedifferentstylequick- disconnectssotheycanonlyattachtothe breathingapparatus.
Freshairbreathinghoodsofferthemostprotection totheface,head,andneck.
Whileworkinginasprayenvironmentor withmaterialsthatproducehazardous vapors,theuseofcompressedair breathingequipmentmayberequired. Therearetwocommontypesof compressedairbreathingequipment. Theyare:
• freshairmasks,whichallowfresh airtobebreathedandofferno protectiontothefacialskin.
• freshairhoods,whichallow freshairtobebreathedandoffer completeprotectiontothefacial skin.
GradeDbreathingairhasrequirements thatmustbemetandmaintained.An audiblealarmmustbeheardinthe
spraybooth. Severalrequirementsfor gradeDbreathingairinclude:
• nooilvapors. • lessthan10partspermillion
(ppm)ofcarbonmonoxide(CO). • lessthan1,000ppmofcarbon
dioxide(CO2).
• thetypeofcompressedairthatis requiredforrefinishing
• howtousecompressedair.
Thispageisintentionallyleftblank.
Module3-Spray Environment
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 27
• describingthetypesof sprayboothscurrentlyinuse.
• identifyingthevariousadjustments thatcanbemadewithina spraybooth.
• explainingthedifferentcontrols andsettingsofaspraybooth.
• explaininghowtomaintaina spraybooth.
Theprepdeckmaybeusedforsandingorsprayinga limitedamountofmaterial.
Prepdecksmayappearsimilarin appearancetothatofaspraybooth. Thedifferencebeingisthataprepdeck typicallyhascurtainsandnotsolidwalls. Prepdecksmay:
• beusedasasandingstation. • allowrefinishmaterialstobe
applied. • beheated. • beusedforedgingparts. • beregulatedbylocalrules.
Somelocalornationalfirecodesmay regulatethetypesofdutiesthatmaybe performedinsideaprepdeck.
Asprayboothshouldbeclean,bright,andairtight.
Asprayboothprovides:
temperaturesforsprayingand baking.
• limitedexposuretohazardous chemicals.
• fireprotection. • color-correctedlightingforcolor
matching.
Shownarethethreedifferenttypesofspraybooths; downdraft(topleft),semi-downdraft(topright),and crossdraft(bottom).
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Thethreemostpopulartypesof sprayboothsinuseare:
• downdraft. • semi-downdraft. • crossdraft.
Adowndraftspraybooth:
• isdesignedtocontroloverspray removalanddustmoreeffectively whencomparedtoothertypesof sprayboothsavailabletoday.
• operatesbydrawingairinfrom theceilingandoutthroughthe floor.
• mayhavetheabilitytorecirculate heatedair.Recirculatingheated airallowsgreaterefficiencyofthe heatingsystem.
Airflowsdiagonallyinasemi-downdraftspraybooth.
Asemi-downdraftspraybooth:
• drawsairintothespraybooth fromventsabovethedoorsand evacuatestheairthroughtherear ofthespraybooth.
• allowsforcontrolofdust.Inthe eventthatthereisanydebrisin thespraybooth,insteadofitbeing drawnfromtheroofofthevehicle tothefloor,thedebrisismoved acrossthelengthofthevehicle. Thisallowsmoresurfaceareafor thedebristocontact.
Airflowsthisdirectioninacrossdraftspraybooth.
Acrossdraftspraybooth:
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RefinishingEquipment(REF01e) 29
• drawsairintothesprayboothfrom filtersinthedoorsandevacuates theairthroughfiltersintherear cornersofthespraybooth.
• allowsforcontrolofdust.Inthe eventthatthereisanydebris inthespraybooth,thedebrisis movedacrossthelengthofthe vehicle.Thisallowsgreatersurface areaforthedebristocontact. Thecrossdraftsprayboothdirects mostofitsairflowalongthesides ofthevehicle.Thisisbecause theexhaustfiltersareprimarily locatedattherearcornersofthe spraybooth.
SprayboothAdjustments
Theinternalsprayboothtemperaturecanbeadjusted atthecontrolpanel.
Sprayboothshaveavarietyofadjustments thatcanbeperformed.Theseadjustments caninclude:
• settingtoaspecifictemperature. • airpressure.Thismayinclude
increasingordecreasingthe amountofairenteringandexiting thespraybooth.
• adjustmenttoonespecific temperatureandpressuresetting foraspecifictypeofmaterial.
Theamountofairflowthroughthesprayboothcan affecttheoutcomeoftherefinish.
Toproperlytesttheamountofairflowing throughaspraybooth,theuseofa Magnahelicoramanometerisrequired. ThefunctionofaMagnahelicisto measurethepressureorvacuumina spraybooth.
Toomuchpressureinthesprayboothis called“positivepressure.”Thisoccurs whenmoreairisenteringthespraybooth thanisexiting.
Toomuchvacuuminthesprayboothis called“negativepressure.”Thisoccurs whenmoreairisexitingthespraybooth thanisentering.
Prepdecks,likespraybooths,maybeable tobebalancedbywatchingthecurtains. Toomuchpressurecausesthecurtainsto pushout.Toolittlepressurecausesthe curtainstodrawintotheprepdeck.
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Toolittleairflowmaycausepoormaterialtransfer.
Settingthesprayboothtocreateavacuum ornegativepressuremaycause:
• avacuumwithinthespraybooth. • dirttobedrawninfromoutside
thespraybooth. • impropermaterialtransfer.
Sprayboothpressureismonitoredwiththe useofaMagnahelicormanometer.
Toomuchincomingairflowwillnotevacuatedust andoverspray.
Positivepressureoccurswhenmoreair isenteringthespraybooththanisexiting. Settingthesprayboothtocreateapositive pressuremaycause:
• thesprayboothtobecome pressurizedandforcerefinish materialintotheshop environment.
• dirttobeheldoutsideofthe spraybooth.Thishappensbyair pressureseepingpastandthrough sealsandgaskets.
• overspraytonotberemovedfrom thespraybooth.Thisiscausedby insufficientexitingairflow.
Dirtyfilterswillrestrictairflow.
Restrictedairflowormovementthrougha sprayboothmayindicatethat:
• therearedirty,restrictedfilters. • thesprayboothbafflesarenot
functioningproperly. • refinishingisperformedinone
areaofthespraybooth.
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Sprayboothfiltersshouldbereplacedonaregular schedule.
Sprayboothfiltersrequirereplacement atvariousintervalsdependingonthe amountofhoursthesprayboothfilters havebeenexposedtopaintanddebris. Thereplacementofsprayboothfiltersare importantbecause:
• asprayboothshouldnotbe balanceduntilafterthefiltershave beenreplaced.
• cleansprayboothfiltersaidin producingaqualityrefinish.
• insomegeographicalareas thebuildupofdebrismaybe consideredahazardousmaterial andmayrequirespecialdisposal oftheusedfilters.
Allsprayboothfiltersshouldbecheckedfor replacementonaregularbasis.
Thereareavarietyoffiltersusedina downdraftspraybooth,includingthe:
• intakefilters. • pre-filters. • ceilingfilters. • in-floorfilters. • recirculationfilters.
ControlsAndSettingsOfASpraybooth
Sprayboothtemperaturecanbeadjustedtomatch refinishmaterialrequirements.
Thethreemaincyclesofaspraybooth includethe:
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• spraycycle,whichcontrolsthe sprayboothconditionswhilethe technicianisapplyingrefinish materials.
• purgecycle,whichevacuates excessoversprayanddebrisfrom thesprayboothbeforebaking.
• bakecycle,whichaidsinthe dryingandcuringoftherefinish material.
Thesecyclesmaybeonacontrol panelthathastobereseteverytimea changeoccurs,ortheymaybeableto bepreprogrammedintothespraybooth controlcenterfordifferenttypesof materials.
Thesprayboothtemperatureisdisplayedduringthe spraycycle.
Thespraycycleallowstherefinish techniciantoadjustandmaintainproper sprayboothtemperatures.Withtheability tomanipulatethetemperatureateach stagearefinishmaterialisapplied,the refinishtechnicianshouldbeableto attaintopqualityresults.
Thesprayboothtemperatureandtimeleftis displayedduringthepurgecycle.
Thepurgecycleallowstherefinish techniciantimebetweenthespraycycle andthebakecycletoevacuatesolvents, moisture,debris,andothercontaminants withinthespraybooth.Withtheabilityto manipulatethisenvironment,therefinish technicianshouldbeabletoattaintop qualityresults.
Thesprayboothtemperatureandtimeleftis displayedduringthebakecycle.
Thebakecycle,whichfollowsthepurge cycle,allowstherefinishtechnicianto acceleratethedryingtimeofrefinish materials.
Althoughtherefinishtechnicianhas theabilitytodryandcurerefinish materialsfasterthanjustairdrying,the
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technicianstillneedstorealizethatthere arevariablesthatcancausepoorresults ifthepaintmaker’sguidelinesarenot followed.
VehicleProtection
Vehiclesthatusecompressednaturalgas shouldhavethetanksremovedbeforethe vehicleismovedintoaspraybooth.
Illustratediswhatoccursduringthedryingand curingprocess.
Afterrefinishmaterialsareapplied,there aretwoprocessesthatoccur.Thereisthe stateof:
• dryingwhentheevaporationof solventsandliquidsareremoved fromthematerial.
• curingwhenachemicalchange occurswithintherefinishmaterial.
Surfacetemperaturecanbemeasuredusinga noncontactsurfacethermometer.
Availablesurfacetemperature thermometersinclude:
• magneticandpaperthermometers, whichcanbeplacednearthearea beingheated.
• noncontacttypethermometers, whichcanbeusedfroma distance.
Somesprayboothsrecirculateheatedair.
Sprayboothburnerefficiencyhasto dowiththedesignofthespraybooth andtheabilitytorecirculateheated air.Somesprayboothsaredesignedto recirculatetheheatedairduringthebake cycle.Thiskeepstheburnersfrombeing
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overworked.Aspraybooththatisdesigned toconstantlyheattheoutsideairwithout reclaiminganyoftheheatedaircauses inefficientheating.
Shownisaportableinfraredlamp(topleft),hand heldmulitpliers(bottomleft),andventuriblowers (right).
Whendryingorcuringtheappliedfinish, therearebothportableandpermanent dryingandcuringtools.Portabletools include:
• infrared(IR)heaters,whichusea typeoflamptocreatetheheating effect.
• handheldmultipliers,usedwith waterbornematerials.
Permanentdryingandcuringtoolsmay be:
• venturiblowers,alsomountedon thesprayboothwalls.
• convectionheat,whichisheated airforcedfromtheceilingtothe floor.
AportableIRheatingunitcanbemovedaroundthe shopforconvenience.
PermanentandportableIRheatingunits operatebyusingshortandmediumwave lengthsfromthelightspectrum.
Thesewavestravelthroughtheairheating onlythesolidobjecttheycontact.As thewavelengthspenetratetherefnished surface,theentirefilmthicknessisheated, thusaidinginthereleaseofsolventsand dryingofthematerial.
Venturiblowersareusedtoremovewaterfrom waterbornematerials.
Unheatedsprayboothairisblownthrough smallventuri-styleblowers.Thistypeof blower:
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• maybeportableorpermanently mountedinthespraybooth.
• isusedtoremovethemoisture fromwaterbornematerials.
Sprayboothburnersarelocatedontheairintakeside ofthespraybooth.
Theconvectionheatingsystem operatessimilartoanoven.Thereare burnerslocatedontheairintakeofthe spraybooth.Beforetheairentersthe spraybooth,itisheatedbytheburners, andthewarmairisdirectedacrossthe vehicle.
SprayboothMaintenance
Shownaresprayboothwallsthathavespraybooth wrapapplied.
Toensurethataqualityrefinishis obtained,therearecertainspraybooth cleaningproceduresthatneedtobe performedonaregularbasis.These proceduresinclude:
• vacuumingthesprayboothfloor. • sandblastingthefloorgratesto
removeexcessiveoverspray. • wipingdownthedoorsealsto
preventdirtfromgettingintothe spraybooth.
• wipingdownthewallstokeep themwhiteandfreeofdebris.
• applyingsprayboothmaskingto thewallsofthespraybooth.This willhelpeliminateoversprayfrom stickingtothesprayboothwalls.
• applyingsprayboothwrap, referredtoasDirtTrapby3M, tothewallsandfloorofthe spraybooth.Thisimprovesthe refinishqualitybytrapping airbornecontaminants.
Referto“Video:BoothWrap-3MDirt TrapInstallation”inthepresentation.This videodiscusseshowtoinstall3MDirt Trap.
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RefinishingEquipment(REF01e) 36
Specialdiagnostictoolsmayberequiredto determinesprayboothproblems.
Whenasprayboothdoesnotoperate properly,thereisspecializeddiagnostic equipmentthatmaybeusedtodetermine thecauseoftheproblem.Thesetools includea:
• maintenancechecklist. • velometer. • smokegenerator. • particlecounter. • lightmeter.
Avelometermeasurestheexchangeofairthrougha spraybooth.
Velometersareusedwhentheremaybe aconcernaboutairflowproblemswithin aspraybooth.Thesemetersmeasure
theamountofairflowingthroughthe spraybooth.
Asmokegeneratorisusedtoshowhowairflowis directedoverthesurfaceofavehicle.
Smokegeneratorsareusedtoobservethe amountanddirectionofairflowthrough aspraybooth.Thetechnicianusesthe smokegeneratortoemitsmokearound avehiclepositionedinasprayboothto determinethepaththesmoketakestothe exhaustfilters.
Shownisaparticulatecounter.
Themainfunctionoftheparticulate counteristo:
• measuretheamountofdebrisin theair.
• determineiftheamountofdebris isexcessive.
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RefinishingEquipment(REF01e) 37
• helpdeterminereplacement intervalsforthesprayboothfilters.
Sprayboothlightingshouldbeasclosetonatural daylightaspossible.
Sprayboothlightinghasthreeimportant variables.Thesevariablesinclude:
• colortemperature.Color temperatureismeasuredinKelvin.
• colorrenderingindex,orCRI.The CRIshouldbegreaterthan93%.
• candlepower.Candlepowershould be5-10kfootcandles.
Thetechnicianisusingalightmeter.
Whileusingalightmeter,thetechnician shouldbeableto:
• determinethecurrentcolor renderingindex(CRI)ofthe sprayboothlighting.TheCRIis howclosetonaturaldaylightthe lightingis.
• determinethecurrent candlepowerofthespraybooth lighting.
Ifanyofthesemeasurementsshowto bebelowtheproperlevel,theglass lensesshouldbecleanedandthe levelsrechecked.Ifstillincorrect,bulb replacementisrequired.
Sprayboothlightbulbsshouldbereplacedona regularbasis.
Sprayboothlightsshouldbereplaced onaregularschedule.Failuretoreplace sprayboothlightsmaycauseproblems, suchas:
• bulbschangingcolorwithage. • bulbsburningoutatvarioustimes
duringsprayboothoperationand use.
• poorcolormatches.
• thetypesofsprayboothscurrently inuse.
• thevariousadjustmentsthatcan bemadewithinaspraybooth.
• thedifferentcontrolsandsettings ofaspraybooth.
• howtomaintainaspraybooth.
Module4-Mixing Equipment
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RefinishingEquipment(REF01e) 41
MixingRoomAndTools
• explainingmixingratios. • describingthedifferencebetween
cottonandnylonpaintstrainers. • describinghowandwheremixing
sticksandcupsareused. • explaininghowtodisposeof
excessrefinishmaterials.
Mixingroomscontainthematerialsandequipment forpreparingrefinishmaterials.
Thepaintmixingroomisdesignedto:
• beself-ventilating. • containanyspillsthatoccur. • meetlocalfirecodes. • begroundedtoavoidsparksand
explosions. • haveexplosion-proofwiring.
Differentamountsofmaterialareneededfor differentmixingratios.
Mostproductsusedforrefinishingin theautomotivecollisionrepairindustry requirethattheybemixedorreduced. Dependingonthetypeofpaintsystem therecanbedifferentmixingratios used.
Someofthemixingratiosmayinclude:
• 3:1=3partsto1part.A3:1ratio istakingpartsoftwoproductsand mixingthemtogether.Examples ofthisaremixing: 3ozofone primerand1ozofhardeneror 10.5ozofoneprimerand3.5oz ofhardener.
• 3:1:1=3partsto1partto1 part.A3:1:1ratioistaking threeproductsandmixingthem together.Examplesofthisare mixing: 3 ozofprimerand1oz ofhardenerand1ozofreducer or10.5ozofprimerand3.5ozof hardenerwith3.5ozofreducer.
• 1:1:10-20%=1partto1part +10-20%ofapart.A1:1:10- 20%ratioistakingequalpartsof twoproductsandmixingthem together.Thenbydoingamath
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RefinishingEquipment(REF01e) 42
equation,figureoutfromthe mixedproducthowmuchofthe mixedproductis10-20%,then addthat10-20%quantityofthe thirdproduct.Examplesofthisare mixing:1ozofpaintand1ozof reducerandthen0.1-0.2ozof atomizingagentor15ozofpaint and15ozofreducerandthen1.5 -3.0ozofanatomizingagent.
Mixingcups,viscositycups,paintfilters,andmixing sticksareallimportanttoolsneededtohelpcreatea qualityrefinish.
Thetoolsthatmaybeneededwhen mixingrefinishmaterialsinclude:
• mixingratiocupsandsticks, whichareusedforobtainingthe properblendofmaterials.
• alint-freestrainer.Strainersshould betestedforresistancetosolvents andwater.Soakthestrainerfor acoupleminutesinwaterand alsoinsolvent.Debriscould endupinthepaintcupifthere isanychangetothestrainer. Strainersalsoshouldhavenylon meshinsteadofcotton.Thisis becausecottonhaslintthatcanbe depositedintothepaintcup.
• aviscositycup.Aviscositycupis usedtogaugehowfastamaterial canpassthroughagivensize orifice.Thiswillthendetermine thespraygunsetupthatisneeded.
Mixingratiocupshavegraduatedscalesontheir sides.
Mixingratiocupsareusedformixing paint,reducer,andhardener.Mixingratio cupsmayhavegraduatedscalesonthe sidesofthecuptoaidinpropermixtures. Differentmixingratiocupsmayhave:
• ascaleformixing.
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RefinishingEquipment(REF01e) 43
• parallelsides.Thebottomof themixingratiocupshouldbe perpendiculartothesidestohelp ensurepropermixingisattained.
• agraduatedscaleforcupsthat havenonparallelsides.
Mixingstickstypicallyhavespecificmixingratios embossedonthemforeaseofuseandreuse.
Mixingsticksareavailablebymost paintmakers.Paintmakersthatoffer mixingstickswillhavemixingsticks neededtosupporttheirmixingformula requirements.Whenusingmixingsticks, guidelinesmustbefollowed.Whenusing amixingstick:
• placethestickinacontainerand followtheappropriatescale.
• donotsetthematanangle. • thescalesmustbefollowed
exactly. • usecontainerswithnontapered
sides. • thecorrectstickfromthepaint
makerneedstobeused.Each paintmakerhastheirownsetof mixingsticksmadeespeciallyfor theirratios.
Viscositycupsareusedtomeasurethethicknessof therefinishmaterial.
Viscositycupsareusedtomeasurethe rateofmaterialflow.Therearedifferent typesofviscositycups.Besuretouse thecorrectcupfortheapplication requirements.Differenttypeofviscosity cupsmaybeabletobeinterchanged insomeapplications.Threecommon viscositycupsusedincludetheZahn, Ford,andDincup.
Shownisasolventrecycler.
Usedmaterialcontainersaredesigned forholdingsmallamountsofwastefora shortperiodoftime.Thesecontainersmay also:
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RefinishingEquipment(REF01e) 44
• holdusedmaterialuntilplacing intolargerholdingdrums.
Whenusingausedsolventcontainer,itis asafepracticetouseasystemthathasa coverandkeepsfumesfromescaping.If anuncoveredcontainerisused,thefumes cancauseafireandhealthhazard.
ModuleWrapUp
• mixingratios. • thedifferencebetweencottonand
nylonpaintstrainers. • howandwheremixingsticksand
cupsmaybeused. • thedisposalofexcessrefinish
materials.
Spraybooth Maintenance