Pump bodies and sealed housings: coaxial bores, sealing faces and 100% leak testing

Leaks in a pressure housing usually start at thin water-passage walls, flange roots and spigot roots: once entrained gas links up with shrinkage in a heavy section, it forms a path that only shows under pressure. At the same time, the coaxiality of the bearing and seal bores and the flatness of the cover face decide whether the seals stay compressed over the part's life.

We form the critical bores and joint faces in the same die half and add local squeeze at heavy sections; CNC roughing and finishing are separate operations, with bores taken in one setup. Every pressure part is leak tested, at up to 0.6 MPa to your standard; at 0.25 MPa held for 30 s the leak rate is typically kept under 0.5%. In the cases published here, a water pump housing holds φ0.05 mm coaxiality with its leak rate cut from 6.2% to under 0.5%, and an oil pump end cover is flat to 0.02 mm.