There are many forms of tooth profile, among which the involute profile is the most common. There are two kinds of methods of involute forming.

Gear milling

Milling gear with disc modulus milling cutter or finger milling cutter belongs to forming processing, and the profile of cutter tooth section corresponds to the shape of gear teeth. The processing efficiency and accuracy of this method are low, and it is only suitable for single piece and small batch production.

Form grinding

It also belongs to the forming process, because the grinding wheel is not easy to be trimmed and used less.

Hobbing

It belongs to generative machining, and its working principle is equivalent to a pair of helical gears meshing. The prototype of gear hob is a spiral gear with a large helix angle. Because the number of teeth is very small (usually the number of teeth is Z = 1) and the teeth are very long, a worm with small helix angle is formed around the shaft. After slotting and relieving teeth, it becomes a hob with cutting edge and back angle.

Shaving

Shaving is a common finish machining method for non hardened tooth surface in mass production. Its working principle is that the shaving cutter and the gear to be machined are meshed freely, and with the help of the relative slip between the two, fine chips are shaved from the tooth surface to improve the accuracy of the tooth surface. Shaving can also form drum shaped teeth to improve the position of tooth surface contact area.

Gear shaper

In addition to hobbing, gear shaper is a kind of gear cutting technology using generation method. In gear shaping, the gear shaper cutter and the workpiece are equivalent to the meshing of a pair of cylindrical gears. The reciprocating motion of the gear shaper cutter is the main motion of the gear shaper, and the circular motion of the gear shaper cutter and the workpiece according to a certain proportion is the feed motion of the gear shaper.

Gear grinding by generative method

The cutting motion of gear grinding by generative method is similar to that of hobbing, which is a kind of gear profile finishing method, especially for hardened gears, it is often the only finishing method. Worm wheel, cone wheel or disc wheel can be used for gear grinding.