As metallurgists and engineers will confirm, nickel-boron coatings such as Nickel 60A are notoriously difficult to work. In fact nobody, until now, has really been able to properly grind it so valve manufacturers using this coating performed all necessary adjustment operations on the ball seats instead.
Looking to solve this problem, SAPORITI teamed up with one of the top suppliers of grinding tools to find a way to sucessfully work this coating. Tests have recently been performed for a customer in China who is delighted with the results and the accuracy that can be realized.
The ball, worked on a SAPORITI PV500XD grinding machine, had a DN 400 port with an OD of 590 mm. The accuracies reached are: Roughness Ra 0.475 and Roundness 0.0084. It should be noted that this unusual material does not have a uniform texture but, as it is a powder that is welded onto the rough metal ball and heated in a furnace, the behaviour is strongly dependant on the dimensions of the ball.
Thanks to more than twenty years’ experience in manufacturing grinding machines for ball valves and seventy-five years in the machine tool field, SAPORITI is convinced that this development will herald a new era in grinding balls for valves.
The company notes that the user-friendly PV 500XD grinding machine is suitable for balls from 2” up to 16” (max OD 595 mm). Moreover the inclined shape permits an ideal view of the working area.
