Injin rufi shine injin rufi wanda zai cika kwantena tare da kunshin kunshin, bayan kayayyakin da aka saka a cikin kwantena na kunshin kunshin, don cewa samfurin zai iya hatimi don adanawa, kiyaye ingancin samfurin, kauce wa asarar samfurin, ana buƙatar rufi kwantena na kunshin kunshin, wannan aikin an yi shi a kan injin rufi.

Injin rufi yana nufin injin rufi kwantena bayan shirye-shiryen kwantena. Yin kayan da yawa na kunshin kwantena, kamar takarda, filastik, gilashi, yumbu, karfe, kayan haɗuwa, da dai sauransu, siffar kunshin kwantena da kaddarorin jiki sun bambanta.