Roller burnishing

Process used to obtain mirror finishes inside metal holes

Roller burnishing is a surface finishing technique where hardened rollers cold work surface imperfections to reduce surface roughness. Roller burnishing differs from abrasive surface finishing techniques in that material is displaced rather than removed. The tooling typically consists of a hardened sphere or cylindrical roller. The tooling is pressed into the surface of the part while it is rotated. The burnishing tool rolls against the surface of the part at a constant speed, producing a very consistent finish across the part. A surface finish of less than Ra 0.1 μm is achievable with roller burnishing. A side effect is that the outer surface of the part is work hardened.

This keyword could refer to multiple things. Here are some suggestions: