How To Deal With The Hardened Surface Of 1-piece Ball Valve?

Because the sealing surfaces of 1 Piece Ball Valve are made of ultra-hard materials or surface-hardened (≥45 HRC / ≥950 HV), machining with conventional tools is difficult. Even if machining is possible, the accuracy may not meet the required requirements. Therefore, selecting the appropriate tooling is crucial.

Precision grinding of balls is generally performed using a specialized grinding machine, which primarily consists of a rotating shaft for clamping the ball and a grinding head. The grinding head primarily comprises a centering flange (connecting plate) connected to the shaft, a spring-loaded floating mechanism, a grinding wheel clamping plate, and grinding wheels. Depending on the surface treatment of the ball, grinding wheels can be made of various oilstone or synthetic diamond materials.

The base material of the seat of a metal-seal ball valve should be stainless steel with a linear expansion coefficient close to that of the housing material. The sealing surface can also be hardened using manual cladding or plasma spray welding of cemented carbide. The final thickness of the overlay layer should be...

Typically, the sealing surface of a metal-seal ball valve seat is precision-ground simultaneously with the ball using a planetary grinding principle on a specialized ball mill. It is then manually ground one-on-one with the ball and inspected using the indentation method.