Superfinishing, also known as microfinishing[1] and short-stroke honing, is a metalworking process that improves surface finish and workpiece geometry.
The stone is oscillated or rotated while the workpiece is moved in such a way that each bonded grain of abrasive follows a random path with variations in speed, direction and pressure.
This multi-motion is a key feature of superfinishing because it prevents the sort of smeared finish that results from built up edge.
[3] Superfinishing differs from grinding in that the relative speed between the abrasive and workpiece is kept low enough to avoid heating and the pressure is light.
This "multi-motion" is critical to achieving the finest possible finish because it prevents re-formation of an amorphous layer of smear metal due to built up edge.
Common abrasives used for superfinishing include aluminum oxide, silicon carbide, cubic boron nitride (CBN) and diamond.
[7] Superfinishing was conceived of by the Chrysler Corporation in 1934 in response to widespread damage sustained by wheel bearings installed in automobiles shipped by rail from Detroit to California.
[2]: 39 The hand finishing method of removing amorphous "grinding fuzz" from crystalline base metal using sandpaper was then mechanized for low-rate production.