Slitting is a type of metal cutting process where large rolls, or coils, of sheet metal stock are cut using extremely sharp rotary blades. In metal slitting, straight lines are cut lengthwise into the large coil to create strips of metal that are narrower in width. As the coil runs through the slitter, circular blades - one upper, the other lower - make the cuts. These are commonly called knives and can be moved to make sheet metal strips of differing widths. In metal fabrication, slitters often come equipped with multiple knives.