High-precision bearing steel ball processing requires a lot of processes, and generally requires hard grinding after heat treatment. Usually, after the steel ball is heat treated, it is ground by a grinding wheel on the grinding machine. That is, the main function of the hard grinding is to eliminate the soft or light grinding defects, remove the surface oxidation, decarburization, deformation and troostite structure generated during the heat treatment. Defects further improve the accuracy and surface quality of high-precision bearing steel balls.
It should be noted that in order to ensure the accuracy of the high-precision bearing steel ball, it is necessary to inspect the appearance during and after the hard grinding process. This is because in the hard grinding process, problems such as burns may occur.
Therefore, for high-precision bearing steel balls, it is necessary to first check the appearance of the surface for defects, and then check for burns after cold pickling. Burns can usually be divided into secondary tempering burns and secondary quenching burns. Secondary tempering burns are black after cold pickling. The specific method for judging the secondary quenching burn is to gray martensite in the middle of the cold pickling of the high-precision bearing steel ball, surrounded by black troostite, showing linear burns, spot burns and bipolar burns.