北美压铸压铸件公差标准NADCAStandardBrief.docx

北美压铸压铸件公差标准NADCAStandardBrief.docx

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北美压铸压铸件公差标准NADCAStandardBrief

北美压铸压铸件公差标准（NADCA-Standard--Brief）

NADCAStandard

LinearDimensions:

StandardTolerances

LinearDimensions:

PrecisionTolerances

PartingLine:

StandardTolerances

PartingLineToleranceisthemaximumamountofdieseparationallowedfortheendproducttomeetspecifiedrequirementsofform,fitandfunction.ThisisnottobeconfusedwithPartingLineShiftTolerancewhichisthemaximumamountdiehalvesshiftfromsidetosideinrelationtooneanother.

PartingLineToleranceisafunctionofthesurfaceareaofthediefromwhichmaterialcanflowfromonediehalftotheother.ThisisalsoknownasProjectedArea.

ProjectedAreaisalwaysaplustolerancesinceacompletelycloseddiehas0separation.Excessmaterialandpressurewillforcethedietoopenalongthepartinglineplanecreatinganoversizecondition.TheexcessmaterialwillcausetheparttobethickerthantheidealspecificationandthatiswhyProjectedAreaonlyhasplustolerance.ItisimportanttounderstandthatTableS-4A-2（ProjectedAreaTolerance）doesnotprovidePartingLineTolerancebyitself.PartthicknessordepthmustbefactoredintogiveatrueideaofPartingLineTolerance.PartingLineToleranceisafunctionofpartthicknessperpendiculartotheProjectedAreaplustheProjectedAreaTolerance.

Example:

Analuminumdiecastinghas75in2（483.9cm2）ofProjectedAreaonthepartingdieplane.FromtableS-4A-2,ProjectedAreaToleranceis+0.012.ThisiscombinedwiththetotalpartthicknesstolerancefromtableS-4A-1toobtainthePartingLineTolerance.

Thetotalpartthicknessincludingbothdiehalvesis5.00in.（127mm）whichismeasuredperpendiculartothepartingdieplane（dimension“E2E1”）.FromtableS-4A-1,theLinearToleranceis±0.010forthefirstinchand±0.001foreachofthefouradditionalinches.TheLinearToleranceof±0.014inchesiscombinedwiththeProjectedAreaToleranceof+0.012toyieldaStandardPartingLineToleranceof+0.026/-0.014in.orinmetricterms±0.35mmfromLinearTolerancetableS-4A-1plus+0.30mmfromProjectedAreaTolerancetableS-4A-2=+0.65/-0.35mm.

PartingLineShift:

StandardTolerance

Example:

PartingLineShiftTolerance

Thecavityareaatthepartinglineis75inchessquared.FromTableS-4A-6,theProjectedAreaPartingLineShiftToleranceis±0.006（±0,152mm）.ThisisaddedtotheLinearTolerancefromtableS/P-4A-1.

DraftRequirements:

StandardTolerances

Inthecaseofaninsidesurfaceforanaluminumcastpart,forwhichtheconstant“C”is30（6mm）,therecommendedStandardDraftatthreedepthsis:

CoredHolesforCutThreads:

StandardTolerances

Coredholesforcutthreadsarecastholesthatrequirethreadstobecut（tapped）intothemetal.Thetablebelowprovidesthedimensionaltolerancesfordiameter,depthanddraftforeachspecifiedthreadtype（UnifiedandMetricSeries）.Whenrequired,coredholesinAl,Mg,ZnandZAmaybetappedwithoutremovingdraft.ThisStandardTolerancerecommendationisbasedonallowing85%offullthreaddepthatthebottomD2（smallend）ofthecoredholeand55%atthetopD1（largeend）ofthecoredhole.Acountersinkorradiusisalsorecommendedatthetopofthecoredhole.Thisprovidesreliefforanydisplacedmaterialandcanalsoservetostrengthenthecore.

ThreadsextendthroughthecoredholeasbyY.Xshowstheactualholedepth.Aswiththecountersinkatthetopofthehole,theextraholelengthprovidesrelieffordisplacedmaterialandallowsforfullthreadengagement.Tolerancesbelowapplytoallalloys.

1.2:

General:

0.14”（3.5mm（+/-0.5mm）1.2.1Deviations:

fromthenominalconditionarebaseduponproductfunctionandmanufacturingprocessrequirements.

2Radii:

2.1FilletRadii:

2.1.1General:

0.14”（+0.08/-0.04”）[3.5mm（+2.0mm/-1.0mm）]

2.1.1.1Deviations:

fromthenominalconditionarebaseduponproductfunctionandmanufacturingprocessrequirements.

2.1.2Minimum:

0.060”（1.5mm）

2.2CornerRadii:

2.2.1General:

0.060”（+0.08/-0.04”）[1.5mm（+2mm/-1mm）]

2.2.1.1Deviations:

fromthenominalconditionarebaseduponproductfunctionandmanufacturingprocessrequirements.

2.2.2Minimum:

0.020”（0.5mm）

3Cores:

3.1Guidelines:

Coresshouldbeusedtominimizemachiningstock,andshouldbepulledperpendiculartoeachother.Usesteppedcoreswherepossibletominimizefinishstock,reduceheavysections,andminimizeporosity.

3.2Minimum:

Coredholediametertobe0.25”（6.0mm）inandparalleltothedirectionofdiedraw.

3.3ForholesLessThan:

0.50”（12.5mm）diameterthecoreholelengthtodiameter（L/D）ratioshouldnotexceed4:

1.

3.4ForHolesGreaterThan:

0.50”（12.5mm）diameterthecorepinlengthtodiameter（L/D）ratioshouldnotexceed10:

1

EjectorPinBosses:

SurfaceGeometry:

6.2.1:

0.06”（1.5mm）raisedto0.03”（0.8mm）depressed.

7Trimming&Cleaning:

7.1PartingLines:

7.1.1TrimRibs-GateandPartingLine:

0.12”maximum（1.5mm）7.1.2Gates&Overflows:

0-0.059”（0-1.5mm）7.1.3Flash:

Asspecifiedinnormalstandard.

7.2CoredHoles:

0-0.02”（0-0.5mm）

7.3Openings:

7.3.1:

0-0.06”（0-1.5mm）atthefinishmachinedface7.3.2:

0-0.03”（0-0.8mm）onas-castsurfaces7.3.3:

0-0.01”（0-2.5mm）ofcornerradii

7.4Corners-Sharp:

Notremoved.

7.5EjectorPinFlash（Max.Projection）:

7.5.1:

0-0.12”（0-3.0mm）onmachinedsurfaces.7.5.2:

0-0.04”（0-1.0mm）onas-castsurfaces.

7.6MachinedSurfaces:

0.12”（0-0.3mm）max.

7.7SeamLines:

0-0.02”（0-0.5mm）

7.8Negativetrim（shearing）:

conditionisallowedwhenthenominalwallthicknessismaintained.

Engineering&Design:

AdditionalSpecificationGuidelines

AcceptableEjectorPinMarks

Ejectorpinmarksonmostdiecastingsmayberaisedordepressed.015”（.381mm）.Raisedejectorpinmarksarepreferredforoptimumproduction.Largercastingsmayrequireadditionalejectorpintolerancesforpropercastingejection.

EjectorPinFlash

Ejectorpinmarksaresurroundedbyaflashofmetal.Normally,ejectorpinflashwillnotberemoved,unlessitisobjectionabletotheenduseofthepart.

Alternatively,ejectorpinflashmaybespecifiedascrushedorflattened.

Inthecaseofeithernonremovalorcrushing/flattening,flashmayflakeoffinuse.

Completeremovalofejectorpinmarksandflashbymachiningorhandscrapingoperationsshouldbespecifiedonlywhenrequirementsjustifytheaddedexpense.

Witheachdiecastingcycle,thedieopensandtheejectorplateintheejectorhalfofthedie（Fig.A）automaticallymovesallejectorpinsforward（Fig.B）,releasingthecastingfromthedie.Then,thediecastingisremovedfromthediemanuallyormechanically.

5MetalExtension（Flash）Removal

GuidelinestoExtentofRemoval

Thetablebelowprovidesaguidetothetypesofdiecastingmetalextension（flash）whichoccursintypicaldiecastingsandtheamountofmetalextensionmaterialwhichremainsafter

（1）degating（removalofanygatesandrunnersfromthecasting）,and

（2）commercialtrimmingofdiecastingmetalextension.

Notethatinsomeinstances,wherespecialsurfacefinishcharacteristicsarenotinvolved,themosteconomicmethodofdegatingandmetalextension（flash）removalmayincludeatumblingorvibratorydeburringoperation.

SurfaceFinish,As-Cast

GeneralGuidelinesforAsCastSurfaceFinishonDieCastParts

Thespecificationofexternalsurfacefinishrequirementsisdesirableforselecteddiecastingapplicationsand,inthecaseofsomedecorativeparts,essential.

Thepurposeoftheguidelinespresentedhereistoclassifyas-castsurfacefinishfordiecastingsintoaseriesofgradessothatthetypeofas-castfinishrequiredmaybeaddressedanddefinedinadvanceofdiedesign.

Theseguidelinesshouldbeusedforgeneraltypeclassificationonly,withfinalsurfacefinishqualityrequirementsspecificallyagreeduponbetweenthediecasterandthecustomer.

Thefirstfourclasseslistedrelatetocosmeticsurfaces.Classfiverelatestoselectedsurfaceareaswherespecifiedsurfacefinishlimitationsarerequired.

7DieCastLetteringandOrnamentation

Lettering,medallions,logotypes,trademarksandarangeofidentificationsymbolsmaybereproducedonthesurfacesofdiecastparts.

Suchas-castornamentationmayberaisedordepressed,butnotethatraisedletteringwillresultinlowerdieconstructioncostsandreduceddiemaintenanceoverthelifeofthedie.

Raisedletteringonadepressedpanelcanbeaneconomicalsubstitutefordepressedletters,asshownintheillustrationbelow.

Cast-inLettering/OrnamentationGuidelines

Inadditiontotheavoidanceofdepressedletteringorsymbolsinthecastingsurface,thefollowingguidelineswillachievethemostsatisfactoryresults.Thetermsusedrefertotheillustrationsbelow.

1.TheLineThickness（or“face”）ofanylettertobeclearlycastshouldbe0.010in.（0.254mm）orgreater.

2.TheHeight（orraiseddimension）ofacastletterorsymbolshouldbeequaltoorlessthanthelinethickness.

3.TheDraftAngleshouldbegreaterthan10°.

4.Lettersorsymbolscontainingfineserifsordelicatelinescannotbeexpectedtodiecastcleanly.