Abstract
This paper discusses the hobbing of gears made of austempered ductile iron (spheroidal graphite iron), which has recently, become the object of attention as a new material for gears. This iron has many advantages, such as a high strength equivalent to steels, and is an economical material. The cutting of teeth of a hardened gear blank is considered to be very difficult, yet if it be possible, the production cost will be lower because the gear can be used without a finishing operation on the tooth surface, removing the distortion caused by the heat treatments. In cutting tests, at first a basic test was conducted using a fly-tool of the same form as that of one blade of a hob. As a result, it was found that hobbing can be performed by using a tool with a large clearance angle (20°).
