This process is also called grinding. There may be fluctuations, burning and deep scratches on the surface of the brake discs. The operation performed on the lathe to correct and eliminate these deformations is called grinding.
To do this, the thickness of the discs must be sufficient. Because the turning process will reduce the thickness measure while correcting your disc. If the Brake Discs are not thick enough, turning will cause serious financial and moral problems for yourself and others.