METHOD FOR MAKING A LIP TYPE SHAFT SEAL HAVING A RESIN LINER

摘要

A method for molding an annular lip type shaft seal (10) of the type having an annular elastomeric shaft seal element (12) and a resin liner (14) (preferably polytetrafluoroethylene) integrally molded therewith and bonded thereto, including providing a step or shoulder (36) on the mold core (26) to prevent the resin liner (14) from flowing axially beyond a predetermined location during molding. The method includes providing a certain range of acute angles "//c" between the shoulder surface (42) and the liner forming surface (38) of the mold core surface (34), and a certain range of shoulder heights "d" relative to the liner thickness "t", for various values of the initial viscosity of the elastomeric preform (18). The percentage of rejects due to undesired flow of the resin liner (14) during molding has been greatly reduced.