Process Encyclopaedia

Grinding / Polishing

Overview

The basic principle of grinding is similar to that of using sand paper to smooth wood. Where it is used it will be the final finishing operation, with the possible exception of painting. Although grinding wheels (which can be up to 2m!) are commonly found in industry, they are being replaced by abrasive belts. Unusually for a mechanical process, grinding usually works best with harder materials, rather than softer materials.

Materials and shapes

Grinding and polishing are finishing operations used where great dimensional accuracy or a good surface finish are required. Polishing often produces a lustrous surface finish - this is due to softening and smearing of the surface from the frictional heating. Primarily used with metals and ceramics. Although grinding does remove material, almost none of this can be recycled.

Economics

On an industrial scale, the wear on grinding equipment is significant and this adds greatly to the cost. The variable wear on a grinding wheel makes control of automated equipment more difficult and hence expensive. The production rate depends on the level of finish required - the limiting factor is usually the overall cost. As with the other machining processes, grinding and polishing should be avoided if at all possible.