a cup shaped or cylindrical thread protector , having circumferentially spaced , internally projecting lugs , is formed by injection molding of a thermoplastic resin into a female mold cavity having a smooth cylindrical interior and having a male mold member fitting therein and cooperable therewith to define a cup shaped or cylindrical cavity . the male mold member has a plurality of recesses of a size and shape operable to produce said lugs in the molded thread protector produced therein . when the thread protector is molded , the male mold member is rotated about its axis sufficiently to compress said lugs into the cup wall thereof at a time after the thermoplastic has solidified but before it has cooled and is then pulled from within the cup shaped member .