Honing

Honing is a machining process in which an abrasive stone is run along a surface generally the inside of a bore in a very controlled path to improve the geometry and surface finish of the bore. Honing is used in manufacturing for greater precision in bores. In the honing process, honing stones are pressurized radially outward against the inside of a cylindrical bore. Cutting fluids are then utilized to pull chips and the abrasive material away from the surface. Honing is a self-truing grinding process.

This process is very similar to grinding in the construction of the stone and the wheel. The difference between the two abrasive tool is the honing stones will generally break down much easier in spite of the stones being treated with wax to improve life. Honing stones look very much like grinding wheels and people can easily fall to the temptation to think of honing as a form of finish grinding. The complex path of the honing stone overcomes the limitation of the geometric accuracy of grinding. The path is created by the stone moving along two simultaneously. The bore and stone conform to an average of the shape of both the bore and the stone, so the imperfections of the stone are not transferred to the bore.  Because of this, there is no need to true a honing stone unlike a grinding wheel that does require truing throughout a process.

Due to the precision level of the process, honing workpieces can become expensive, but necessary in high quality gear system to insure the center distances and mounting. In that regard honing can be considered a saving when you consider the scrap or time needed to obtain this level of precision from other methods. The higher precision of this expensive process results in a much quieter operation of the components; that can justify the cost of the process.