Ana amfani da injin sosai a cikin man fetur, masana'antar sinadarai, siminti, tukunyar jirgi, ginin jirgi, jirgin sama, kiyaye ruwa, hasumiya mai watsa wutar lantarki da sauran injuna da kayan aiki.Ka'idar aiki ita ce juyawa nakasar lankwasawa.Domin babba abin nadi za a iya motsa sama da ƙasa, don haka babu bukatar ƙarin latsa ko kayan aiki, iya gane lankwasawa, kazalika da gyara na workpiece.