Worm Parts Grinding Cracks Reason Analysis

  Worm is an important part of machine tool rotating parts. Worm spiral surface and worm gear tooth surface slip relatively when working, which is easy to wear. Therefore, the worm will usually carburizing quenching treatment to obtain higher hardness to prevent worm spiral surface wear. Worm parts require high precision, so the processing technology is complex and long. If there is any problem during processing, it will cause big loss. A kind of worm parts in our company appeared grinding cracks during grinding, resulting in parts scrapped, seriously affecting the production schedule. 1. Worm material and main process flow The worm material is 20CrMnTiH and the heat treatment requires carburizing and quenching with a depth of 1.1-1.5mm and a surface hardness of 58HRC after quenching. Blanking→Forging→Normalizing→Rough machining→Stress relieve→Fine machining→carburizing→Carbon remove on the thread→Quenching→Rough grinding→Test→Aging→Fine grinding Heat treatment process: Forging normali