Lathes and turning machines come in many types and sizes to suit specific application requirements. Engine lathes, turret lathes, and NC/CNC turning machines are just a few of the types in use today. Drilling is the production of holes by the relative motion of a rotating cutting tool and the work piece. Drilling machine types include vertical, multiple spindle (gang), radial, and turret. Milling is a machining process for removing material by relative motion between a work piece and a rotating cutter having multiple cutting edges. Power band sawing uses a long endless band with many small teeth traveling over two or more wheels (one is a driven wheel and the others are idlers) in one direction. Grinding is a process used when high surface finish and high dimensional accuracy are needed. The designation nontraditional machining is applied to many mechanical, electrical, thermal, and chemical material-removal processes.