Glossary

Superfinishing is a precision surface finishing process used to improve the smoothness, accuracy, and performance of metal parts beyond what conventional grinding or polishing can achieve. It involves the use of fine abrasive stones or tapes that lightly rub against the workpiece under controlled pressure while the part is oscillated or rotated. This removes only a very thin layer of material—measured in microns—but it eliminates surface irregularities, reduces roughness, and creates a highly refined finish.

The key benefit of superfinishing is that it produces surfaces with extremely low roughness and high dimensional accuracy. Unlike standard polishing, which can leave directional scratches or waviness, superfinishing produces a uniform crosshatch pattern that helps retain lubrication on the surface. This makes it especially useful in components subject to friction, wear, or rolling contact.

Common applications include engine components such as crankshafts, camshafts, gears, and bearings, as well as aerospace and precision tool parts. Superfinished surfaces reduce friction and heat buildup, extend component life, improve load-bearing capacity, and enhance fatigue resistance.

In the context of fasteners and mechanical assemblies, superfinishing may be applied to high-performance bolts, shafts, or washers where smooth, uniform surfaces are critical for reducing wear, improving fatigue strength, or preventing premature failure under high loads.