preparation of feed screw having a wear resistant alloy coating thereon for the injection molding or extrusion of plastic . nickel - based alloys that have shown themselves to be compatible with inlaid barrel liners by virtue of similar wear ratios , modulus of elasticity , ultimate yield strength , and linear thermal coefficients of expansion , are sprayed at high velocity onto a heated feed screw to mechanically bond the alloy to the feed screw . the alloy is then fused to the feed screw in a controlled manner . following the fusing process , the feed screw and alloy thereon is heated and allowed to cool in a highly controlled environment to produce a crack - free dense coating of the alloy on the screw substrate .