Abstract
A gear is one of the most popular machine element parts. It is used to transmit power between two axes, to change speed, to obtain large torque and so on. The history of gear is old. It is known that a wooden gear had already been used since B.C.. Nowadays, steel, cast iron, and plastic are used as gear material, and gears are used at severe conditions. Therefore, it becomes important problem for gears to miniaturize more, and to make the vibration and the noise a more decrease. This research introduced some typical machining methods of gears, reported the influence of machining methods on gear strength, and considered the future of gear as machine element parts.
