Theairholeisthemaindefectintheproductionofthebrakedrumofthebimetalautomobile,andismainlydistributedontheinnerwallandtheouterwallofthebrakedrum.HowcanIpreventitinordertogetacompletebrakedrumcasting?1.Whencastingthebrakedrumcastings,itisnecessarytoreducetheoverheatingtemperatureduringthefinancializationandminimizethecontacttimebetweenthealloyliquidandthegasduringthemelting.Second,wemustpayattentiontothetreatmentofoxidesandstainsonthesurfaceofsteelparts,sothesteelplateshouldbesandblasted;remembertodrythesteel.Third,intheplacewherethecastironandsteelpartsarecombined,itisnecessarytopayattentiontothebrushingofthegetteringpaint.Fourth,opentheexhaust(overflow)riserintheprocesstomakethegasinthecavitytimely