a dead center (one that does not turn freely, i.e., "dead") may be used to support the workpiece at either the fixed or rotating end of the machine. when used in the fixed position, a dead center produces friction between the workpiece and center, due to the rotation of the workpiece. lubrication is therefore required between the center and workpiece to prevent friction welding from occurring. additionally the tip of the center may have an insert of cemented carbide which will reduce the friction slightly and allow for faster speeds. dead centers are typically fully hardened to prevent damage to the important mating surfaces of the taper and to preserve the 60° angle of the nose. as tungsten carbide is much harder than steel, a carbide-tipped center has greater wear resistance than a steel center.