Simintin kumfa da aka rasa wani yanki ne na simintin yashi wanda ke amfani da taimakon busasshiyar yashi don samar da simintin gyare-gyare. Simintin kumfa da ya ɓace yana nufin sassan simintin simintin gyare-gyaren da aka yi ta hanyar asarar kumfa. Ƙarfe na ƙarfe da maras ƙarfe, gami da baƙin ƙarfe simintin toka, baƙin ƙarfe ductile, baƙin ƙarfe malleable, ƙarfe carbon, gami da gawa na aluminum ana iya jefa su ta hanyar jefar da kumfa.Batar da Kumfa, LFC a takaice, wanda kuma ake kira Full Mold Casting, wani nau'in simintin simintin gyare-gyare ne na Evaporative Pattern Casting (EPC) tare da busasshen simintin simintin yashi. EPC wani lokaci yana iya zama gajere don simintin simintin gyare-gyaren da za a iya kashewa saboda bacewar ƙirar kumfa sau ɗaya kawai. Bayan an gama tsarin kumfa ta hanyar injina na musamman, sannan ana lulluɓe ƙirar filastik ɗin kumfa tare da abin rufe fuska don samar da harsashi mai ƙarfi don tsayayya da narkakken ƙarfe. Ana saka sifofin kumfa tare da bawo a cikin akwatin yashi, kuma a cika shi da yashi busassun yashi a kusa da su. A lokacin da ake zubawa, ƙarfe mai zafi mai zafi yana sa tsarin kumfa ya zama pyrolyzed kuma ya "bace" kuma ya mamaye kogon fita na tsarin, kuma a ƙarshe an sami simintin gyare-gyaren da ake so.
