The production of steel balls (especially for the bearing industry) is a multi-stage process. After the blank has been cut to length, forged, flashed and cured, it is pre-ground with vitrified bonded silicon carbide grinding wheels. After this process the nearly finished balls are subjected to a 2- to 3-stage fine grinding process with resin-bonded aluminium oxide grinding wheels in grit sizes ranging between 280 and 1500.
Classification in so-called G-classes
The balls are then classified in so-called G-classes, whereby a G12 rating is currently regarded as the standard for precision balls. More and more ball manufacturers are striving for grades up to G5.
Due to the enormous forces generated (as a result of the extremely high number of balls that are located between the wheels at the same time), grinding wheels with the hardest possible grade, i.e. hardness grade Z, are produced for both grinding processes.