Gear manufacturing basically is categorised based on the type of gear to be manufactured. The types of gears can be classified as follows:
- Worm Gears
- Bevel Gears
The manufacturing methodology involved for manufacturing of the above types of gears defines the types of machines to be used. The various production methods for producing the above mentioned gears by machining are as follows.
a) Gear Milling: This is one of the initial and best known and metal removal process for making gears. This method requires the usage of a milling machine. It is also to be noted that this method can produce nearly all types of gears. The method involves the use of a form cutter, which is passed through the gear blank to create the tooth gap. This method is right now used only for the manufacture of gears requiring very less dimensional accuracy. To put it correctly this method is currently outdated.
b) Gear Hobbing: Gear Hobbing is a continuous generating process in which the tooth flanks of the constantly moving work piece are formed by equally spaced cutting edges of the hob. The main advantage of this process is its versatility to produce a variety of gears including Spur, Helical, Worm Wheels, Serrations, Splines, etc. The main advantage of the method is the higher productivity rate of the gears.
c) Gear Shaping: Gear shaping is a generating process. The cutter used is virtually a gear provided with cutting edges. The tool is rotated at the required velocity ratio relative to the gear to be manufactured and any one manufactured gear tooth space is formed by one complete cutter tooth. This method can be used to produce cluster gears, internal gears, racks, etc with ease, which may not have the possibility to be manufactured in gear hobbing.
d) Bevel Gear Cutting: Bevel gear cutting is a very specialized area in the field of gear cutting. This involves a special type of machine for each variety of the bevel gear to be manufactured. Some of the bevel gear types along with the type of machines required are Gleason, Oerlikon, Hypoid, Zerol, etc. Each type of bevel gear is always manufactured only on the corresponding type of machine against its name. The tooling required also tends to vary based on the type of gear.