Roll Crushing - 911 MetallurgistFeb 23, 2016 . The crushing action of roll crushers on rock is completely by . as the surface speed increases; also, it will increase as the angle of nip is.angle of nip in roll crusher,Angle of nip | Article about angle of nip by The Free DictionaryThe largest angle that will just grip a lump between the jaws, rolls, or mantle and ring of a crusher. Also known as angle of bite; nip. (mining engineering).