Plastic headed fastener assembly

Claim 1

A threaded fastener with a composite, corrosive resistant head, including a metal body with a threaded shank and an integral radially enlarged head portion at one extremity and a drill point at the other extremity, a pair of slots formed in the head portion intersecting at right angles at their midpoints and at the axis of the threaded shank, the slots extending transversely of the head intersecting the outer periphery thereof, a flange extending radially outwardly of the head the bottommost surface thereof forming the clamping surface of the head portion, the slots defining four upstanding posts, each post thereby including a pair of internal, intersecting planar surfaces extending substantially perpendicular to the base of the slots and to each other, the base of the slots being coplanar and substantially perpendicular to the longitudinal axis of the fastener, a thin-walled, substantially uniform thickness of corrosive resistant thermoplastic coating covering all surfaces of the enlarged head portion including the flange, the outer periphery of the flange and at least the radial outermost surface region of the surface beneath the flange forming the clamping surface, the composite head thus providing a cruciform slot configuration presenting eight substantially equal, flat internal bearing surfaces maximizing the surface area on which a mating driving tool applies a rotary inducing force on four of said internal surfaces when torque is applied in a given direction compressing the plastic coating against the upstanding posts to minimize the stress on the thermoplastic material when subjected to large torque required in drilling and setting the fastener.