The flywheel ring gear a part attached to the flywheel or flexplate of an engine. Sometimes, people called it starter ring gear. The ring gear teeth connect with the starter motor teeth when the driver ignites the engine.

 

It's made of steel forging, then the gear teeth are processed by the hobbing tool, followed by processes to chamfer, deburr and clean the gear teeth.

 

Generally, the flywheel ring gear material is SAE1045. After finish the processing, in order to increase the surface hardness, we need to do induction hardening to make the hardness at pitch circle diameter in the range of 45HRC-55HRC.