Radiiareextremelyimportantindiecastingsandoftenneglectedbycomponentdesigners.Toavoidhighstressconcentrationsinthecomponentandthediecastingtool,filletradiioftheappropriatesizemustbeusedinallinternalandexternalcomponentedges.Theexceptiontothisruleiswherethefeaturelandsonthepartinglineofthetool.Anotherimportantaspectconcerningfilletradiiisthattheyassistinfillingthepart

RecommendedFilletDesigns

LessDesirableFilletDesigns

NotRecommendedFilletDesigns

Thereisanoptimumsizeoffilletwherestructuralpartsareconcerned.Althoughincreasingthefilletsizegenerallywilldecreasethestressconcentrationatthebottomofarib,eventuallythemassofmaterialaddedbythefilletwillinduceshrinkageporosityinthatarea.Designersshouldalsonotethatfilletsappliedperpendiculartothepartinglineofthetoolrequiredraft.

Ribsareusedto:

Increasethestiffnessofacomponent.

Addstrengthtoacomponent.

Assistintheproductionofasoundcasting.

Ifthecomponentinquestionisastructuralpart,carefulconsiderationmustbegiventothedesignofribs,especiallyinareasofhighstress.Properlyproportionedfilletradiimustbeusedtoavoidhighstressconcentrationsatthejunctionoftheribandthemaincomponent.Thiscanalsoassistinproducingasoundcastingbyprovidingameansofdistributingthemetal.Currentdiecastingtechnologypermitsthinneranddeeperribsthanwerepreviouslypossible.Howevertheratioofwidthtodepthdoeshaveasignificantbearingonthedesignofthetoolandtheprocessesusedtomanufactureit.

Thecomponentdesignershouldnotethatcornersandedgesatthepartinglinelocationmustbesharp,whichmaybeundesirablefromthepointofviewofcomponentserviceperformance.Allotherlocationsshouldhavefilletradiitoavoidproblemswithearlydiefailure,andpromotebetterfillingofthecavity.

RecommendedRibDesigns

NotRecommendedRibDesigns

EjectorPins,EjectorPinMarksandEjectorPinFlash

Inordertoremovethecastingfromthedie,movableejectorpinsmaybeused.Thesegenerallyresultinamarkonthecasting,andtheirlocationandsizeshouldbediscussedwithDynacastasearlyaspossibleintheconceptionofthepart.Themarksleftbytheejectorpinscanberaisedordepressed-typically0.3mm(0.012").

FlashRemoval

Necessaryflashremovalcanbereducedbycarefulcomponentdesign.CollaborationwithDynacastearlyinthedesignofcomponentswillresultinmoreeconomicalproduction.

Reducingheavymass

Whenredesigningpartspreviouslymanufacturedbyusingotherprocesses,usingthinnerwallsandribreinforcementcanreduceweightbyeliminatingheavymasses.

Intheexampleabove,thebossshownin(1)isbadduetotheheavymassofmaterialinthewalls,whichwillleadtoporosityandincreasecycletimes.Thebossshownin(2)isbetter,withamoreuniformwallthicknessandtheheavywallsreplacedbyribs.Thebossshownin(3)isalsogoodandrequiresnomovablecoresorcoreslides.

Diesimplification

Somefeatures,suchasundercuts,bossesandholes,requireeithersubsequentmachiningorretractablecoreslidesinthetool,becausethesefeaturesarenotorientatedinthedirectionofdiedraw.Retractablecoreslidescansubstantiallyincreasethecostofmanufacturingandmaintainingatool,andalsoincreasethecastingcycletime.Furthermore,theyalsotendtocauseflashonexteriorsurfacesandattractadditionalcostsforsubsequentremoval.

Examplesofcomponentredesigntoeliminatecoreslidesareshownbelow.

Movablecoresarerequiredin(1),duetotheoutsidefeatures,whereasthecastingcanbemadewithoutmovablecoresorcoreslidesin(2).

EliminatingUndercutsBeneathBosses

Undercutsbeneathbossesformfeaturesthatpreventthecastingbeingejectedfromthedie.Inthesecases,carefulredesigncaneliminatethesubsequentmachiningrequiredortheadditionalcoreslidesrequiredinthetool.Designalternativesthateliminateanundercutformedbyaninteriorbossareshownbelow.

Theoriginalhousingdesignisshownin(1).Thebossescreateundercutsthatcannotbecast.Analternativeisshownin(2)wherethebossesarerelocatedontheoutsideofthebox,eliminatingtheundercuts.In(3)theoriginaldesignhasthebossescoredbyprovidinganopeningthroughthebottomwall.In(4)thebossesareextendedtothebottomwalloftheenclosure,eliminatingtheundercut.However,withouttheadditionalcoringshownin(5),anexcessivemassofmetalwillbepresent.

DieParting

Thediepartinglinelocationmaybeimportanttotheapplicationbecauseofthelineleftonthediecastingwherethediehalvesmeet.Ifrequired,thecastingmustbetrimmedalongthislineandthetrimdiemustbeconfiguredtoitandmaintained.Simplificationofthepartinglineconfigurationwillreducethecostofmanufacturingandmaintainingthetrimdie.Insomecases,asimplifiedpartinglinemaynegatetheneedforclean-upoperationsonexternalsurfaces.

DraftRequirements

Thankstotheprecisionofourprimaryprocesses,we’reoftenabletoeliminateoperationsthattraditionallyneedtobeperformedafterthediecastingprocess.Thissavesyoutimeandmoney.

Inordertomaximizethispotentialbenefit,itisvitaltoinvolveDynacastinyourdesignprocessattheearlieststagepossible.Toapplyvalueanalysisandvalueengineeringtechniques,takeadvantageofourfreeseminarsatyourfacility.Contactustodaytoschedule