Corrosion Protection Textbook Version:3.3 ©2001-2014Inter-IndustryConferenceOnAutoCollisionRepair CPS01-STMAN1-E Thispageisintentionallyleftblank. Textbook CorrosionProtection Contents Introduction..............................................................................................................................7 ObligationsToTheCustomerAndLiability.......................................................................... 7 Module1-CorrosionOriginsAndPrevention.......................................................................13 CausesOfCorrosion...........................................................................................................13 OEMCorrosionProtection..................................................................................................14 PreventingCorrosionDuringRepairs..................................................................................19 ModuleWrap-Up............................................................................................................... 26 Module2-CorrosionProtectionDuringRepairs................................................................... 29 Cleaning..............................................................................................................................29 PartPreparations................................................................................................................. 31 JoiningSurfaces.................................................................................................................. 33 Primers................................................................................................................................36 Aerosols.............................................................................................................................. 40 SeamSealers.......................................................................................................................41 Chip-ResistantCoatings...................................................................................................... 47 ModuleWrap-Up............................................................................................................... 51 Module3-CorrosionProtectionAfterRepairs.......................................................................55 Anti-CorrosionCompound..................................................................................................55 Undercoating...................................................................................................................... 57 ModuleWrap-Up............................................................................................................... 59 Module4-VehicleMakerRecommendations....................................................................... 63 OEMWarranties................................................................................................................. 63 VehicleMaker-SpecificRecommendations......................................................................... 63 ModuleWrap-Up............................................................................................................... 72 TableofContents 3 Thispageisintentionallyleftblank. Introduction Thispageisintentionallyleftblank. Textbook Introduction ObligationsToTheCustomerAndLiability • fit. • finish. Throughoutthedamageanalysisand repairprocesstherepairerandinsurer must: • communicatewitheachother. • maintainconstantcommunication withthecustomer. • beinagreementwitheachother andthecustomeronhowrepairs willbeperformed. Thecollisionrepairindustryhasan • informthecustomerofany obligationtocorrectlyrepairthe changesintherepairplanfrom customer’svehicle.Collisionrepairsmust theoriginalrepairagreement,and beperformedusing: explainthechangesandwhythey havetobemade. • recommendedortested proceduresfromvehiclemakers, I-CAR,andotherresearchand testingorganizations. • qualityreplacementpartsand materials. • repairprocessesandpartsas writtenandagreeduponinthe repairorder.Ifitemsontherepair agreementarenotconsistent withtherepairorder,itcanbe consideredfraud. Performingpropercollisionrepairs Toreduceliability: requiresusingpartsandproceduresthat keepremainingwarrantiesintact. • makesurethatallrepairsare performedthoroughly,correctly Collisionrepairsmustrestore: andaslistedinthedamagereport. • followproperprocedures. • safety. • havedocumentationofrequired • structuralintegrity. repairswithdetailedrecord • durability. keepingavailableforcustomers. • performance. CorrosionProtection 7 Textbook Introduction Techniciansareconsideredthe finish,durability,andperformat expertsandareexpectedtobe leastaswellastheoriginal. knowledgeableonhowtoperform • keepingthoroughrecords. aqualityrepair. Liabilityinsurancethatcoverstherepair facilitymaynotalwayscoveralldamages. Forexample: • thepolicymaynotcover faultyrepairs,leavingliability responsibilitycompletelyonthe facility. • ashopownermayfindthatrepair facilityliabilitycoveragemaynot coverthefullamountawardedin alawsuit.Theshopownerwould Keepingthoroughrecordsincludesmore havetopaythedifference. thanrecordingthedate,mileage,andpre- existingdamage.Recordkeepingalso includes: • makingsureallnotesarelegible. • verifyingtherepairsthatwere madeornotmade. • havingthecustomersigna waiverforrepairsthattheydo notwantperformed.Repairers mustdeterminetheirliabilityon notrepairingsafetysystemssuch Itisdifficulttoreducetheriskofliability asrestraintandanti-lockbrake exposure.Thepartthattherepairercan systems. controlisthechanceofbeingfoundat • keepingcomputerprintoutsor fault.Chancescanbeminimizedby: worksheetsonfileshowingwheel alignmentreadingsorvehicle • usingrecommendedortested dimensionsbeforeandafter proceduresfromthevehicle repairs. makers,ICAR,orotherresearch • keepingscantoolprintoutsand andtestingorganizations. recordsofcomputercodesfor • usingqualityreplacementparts airbag,anti-lockbrake,emission, andmaterialsthatrestorefit, andpowertraincontrolmodule (PCM)systems. CorrosionProtection 8 Textbook Introduction • attachingtheOEMorothertested procedureprintouttothevehicle repairorder. • keepingreceiptsforallsublet workperformed. Referto"Video:TopicsOffLimits"inthe presentation.Thisvideoidentifiestopics thatshouldnotbebroughtupinclass. CorrosionProtection 9 Thispageisintentionallyleftblank. Module1-Corrosion OriginsAnd Prevention Thispageisintentionallyleftblank. Textbook Module1-CorrosionOriginsAndPrevention CausesOfCorrosion Corrosionisanelectrochemicalreaction calledoxidationthatisformedwhen Learningobjectivesforthismodule combiningexposedmetal,oxygen,and include: anelectrolyte,suchasacids,salts,or moisture. • describingthecausesofcorrosion. • listingstepsOEMstakefor corrosionprotection. • describinghowtoprevent corrosionduringrepairs. Asnow-coveredroadlikethislikelyhasaddedroad salt,oneofthemaincorrosionpromoters. Elementsthatpromotecorrosion include: • roadsaltandmagnesiumchloride, Referto“Video:ImportanceOfCorrosion bothusedtomeltsnowandice Protection”inthepresentation.This onroads.Somestatesandregions videodiscussessomeofthereasonswhy havefoundthatsaltisnoteffective restoringcorrosionprotectionisvital inverycoldtemperatures,so duringthecollisionrepairprocess. magnesiumchlorideisbeing substitutedasadeicer.Itisalso usedasadustcontrolagenton unpavedroadsinsomestatesand regions.Magnesiumchlorideis appliedasaliquid.Itishighly corrosivewhenwet,andsticksto metalsurfacesbetterthansalt. • acidrain. • pollutants. • moisture. • collisiondamage,whichbreaks Theformationofcorrosionlikethisrequiresa coatingsandexposesbaremetal. combinationofexposedmetal,oxygen,andan electrolyte. CorrosionProtection 13 Textbook Module1-CorrosionOriginsAndPrevention • impropercollisionrepairs,such OEMCorrosionProtection aswhenrepairedsurfacesarenot treated. Referto"Video:OEM-AppliedCorrosion Protection”inthepresentation.Thisvideo Theexposedmetalinthisonespotisaclassic exampleofacorrosionhotspot,wherecorrosion discussessomeofthecoatingsappliedat formsfasterthanotherareasnotexposed. thefactoryforcorrosionprotection. Corrosivehotspots: • areso-namedbecausethey areexposedmetalareaswhich corrodefasterthanotherareas notexposed.Corrosioncan startinstantlyinsomecases,a conditionknownasflashrusting whichistypicallyvisible. • maybeaspotwithabrokenpaint film. Thisfeatheredgeprofilesthedifferentcoatings • maybeseparatedweldjoints. appliedbytheOEM. • maybedamagedanti-corrosion coatings. Corrosionprotectionmaterialsapplied duringthevehicleoriginalbuild include: • azinccoatingatthesteelmill. • metaltreatment. • anelectrodepositioncoating(E- coat)process. • seamsealers. • chip-resistantcoating. • topcoats. • undercoating. CorrosionProtection 14 Textbook Module1-CorrosionOriginsAndPrevention Thisillustratedgraphshowsthatzincismoreactive thansteel,whichiswhyzincisusedforsacrificial RefertoModule1,“Demonstration:Zinc- corrosiononsteelpanels. CoatedCoupon”inthepresentationforan Acoatingofzinconthesteel: exampleof azinc-coatedcoupon. • isappliedatthesteelmillbefore thesteelisdeliveredtothevehicle makers. • protectsthesteelwith“sacrificial” corrosion.Thisisatypeof corrosionthatisnotdestructive. Themorechemicallyactivemetal, zinc,oxidizesandformsatight bondthatdoesnotflakeoff,thus protectingthesteelunderneath. • iscalled“galvanized”andby Thebody-in-whitegoesthroughaseriesofwashings andrinsestopreparethesurfaceforOEMprimer. variousothernamesdepending onthecoatingprocess.The Oneofthefirsttreatmentsofthestamped “galvannealed”processis andassembledvehicle“body-in-white” electroplatedandheatedtoform atthevehicleassemblyplantismetal azinc-ironalloy.Theprocess