求高手热加工专业英语翻译（铸造类的）专业翻译，勿使用软件翻译谢谢
Asmetalsolidifiesandcools,itshrinksandcontractsinsize.Tocompensateforthis,apatternismadelargerthanthefinishedcastingbyanamountcalledshrinkageallowance.Althoughcontractionisvolumetric,thecorrectionforitisusuallyexpressedlinearly.Dimensionsarenotshownoversizeonapartorpatterdrawingtoallowforshrinkage,butthepatternmakermeasurestothefinisheddimensionswithshrinkrules.Sucharulehasascalethatislongerthanstandardbyadefiniteproportionsuchas5,10,or15mm/m.Shrinkageisdifferentfordifferentmetals,differentshapesofcastingsofthesamemetal,anddifferentmoldingandcastingmethods.
OtherAllowances.Machiningallowanceistheamountbywhichdimensionsonacastingaremadeoversizetoprevidestockformachining.Dimensionsonapatterndrawingincludemachiningallowance.Theamountofmetalleftformachiningmustbenomorethannecessarybutenoughtoassurethatcutterscangetanamplecutbeneathandcompletelyremovethehardscaleandskinonthesurfaceofthecasting.Whatissufficientdependsuponthekindofmetal,theshapeofthecasting,andthemethodsofcasting,cleaning,andmachining.
DistortionallowancemaybeaddedtodimensionsofcertainobjectssuchanlargeflatpiatesandU-shapedcastingsthatareexpectedtowarponcooling.Thepurposeofthisallowanceistodisplacethepatterninsuchawaythatthecastingwillbeofthepropershapeandsizeafteritdistortsinprocess.
