Refinishing Equipment Textbook (REF01e)
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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.
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.
Thispageisintentionallyleftblank.
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).
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 28
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:
Module3-SprayEnvironmentTextbook
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.
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 30
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.
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 31
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:
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 32
• 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
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 33
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
Module3-SprayEnvironmentTextbook
RefinishingEquipment(REF01e) 34
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.
Module3-SprayEnvironmentTextbook
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.
Module4-MixingEquipmentTextbook
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