Abun yumbu yana nufin kayan da ba na ƙarfe ba na inorganic waɗanda aka yi da mahallin halitta ko na roba ta hanyar ƙirƙira da ɓata.Yana da abũbuwan amfãni daga high narkewa batu, high taurin, high lalacewa juriya da hadawan abu da iskar shaka juriya.An yi amfani da hatimin inji mai yumbu a ko'ina a cikin injina, masana'antar sinadarai, man fetur, magunguna, mota da sauran fannoni.
Hatimin injina yana da babban buƙatu game da kayan rufewa, don haka ana ɗaukar yumbu don yin hatimin injin yumbu saboda fasalin gasa.
