we provide laser coating for wear and corrosion protection on screw flight to increase variety of plastic materials in injection applications and the use of abrasive corrosive additives to improve life of screws. the screws are turned into bimetallic structure by hard facing the tops of the flights. in order to minimize the rate of abrasive and corrosive wear, the flights of the new and repaired screws are coated with fe, ni, co based metal alloys.