北美压铸压铸件公差标准NADCAStandard,Brief

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1、.-NADCAStandardLinearDimensions:StandardTolerancesLinearDimensions:PrecisionTolerancesPartingLine:StandardTolerances-.word.zl.-PartingLineToleranceisthemaximumamountofdieseparationallowedfortheendproducttomeetspecifiedrequirementsofform,fitandfunction.Thisisnottobe

2、confusedwithPartingLineShiftTolerancewhichisthemaximumamountdiehalvesshiftfromsidetosideinrelationtooneanother.PartingLineToleranceisafunctionofthesurfaceareaofthediefromwhichmaterialcanflowfromonediehalftotheother.ThisisalsoknownasProjectedArea.ProjectedAreaisalwa

3、ysaplustolerancesinceacompletelycloseddiehas0separation.Excessmaterialandpressurewillforcethedietoopenalongthepartinglineplanecreatinganoversizecondition.TheexcessmaterialwillcausetheparttobethickerthantheidealspecificationandthatiswhyProjectedAreaonlyhasplustolera

4、nce.ItisimportanttounderstandthatTableS-4A-2(ProjectedAreaTolerance)doesnotprovidePartingLineTolerancebyitself.PartthicknessordepthmustbefactoredintogiveatrueideaofPartingLineTolerance.PartingLineToleranceisafunctionofpartthicknessperpendiculartotheProjectedAreaplu

5、stheProjectedAreaTolerance.Example:Analuminumdiecastinghas75in2(483.9cm2)ofProjectedAreaonthepartingdieplane.FromtableS-4A-2,ProjectedAreaToleranceis+0.012.ThisiscombinedwiththetotalpartthicknesstolerancefromtableS-4A-1toobtainthePartingLineTolerance.-.word.zl.-The

6、totalpartthicknessincludingbothdiehalvesis5.00in.(127mm)whichismeasuredperpendiculartothepartingdieplane(dimension“E2E1〞).FromtableS-4A-1,theLinearToleranceis±0.010forthefirstinchand±0.001foreachofthefouradditionalinches.TheLinearToleranceof±0.014inchesiscombinedw

7、iththeProjectedAreaToleranceof+0.012toyieldaStandardPartingLineToleranceof+0.026/-0.014in.orinmetricterms±0.35mmfromLinearTolerancetableS-4A-1plus+0.30mmfromProjectedAreaTolerancetableS-4A-2=+0.65/-0.35mm.PartingLineShift:StandardToleranceExample:PartingLineShiftTo

8、leranceThecavityareaatthepartinglineis75inchessquared.FromTableS-4A-6,theProjectedAreaPartingLineShiftToleranceis±0.006(±0,152mm).Thisisaddedtoth