Eight Processing Methods of Gears

There are various forms of gear profiles, among which involute gear profiles are the most common. There are two main types of processing methods for involute gear profiles, namely forming method and generating method.

Let's take a look at several gear profile processing methods below.

1. Milling

Milling teeth with disc-shaped module milling cutters or gear cutters belong to the forming method of processing. The cross-sectional shape of the milling cutter teeth corresponds to the shape between the gear teeth. This method has low processing efficiency and accuracy, and is only suitable for single-piece and small batch production.

2. Form grinding

Also belonging to the forming method of processing, it is used less due to the difficulty in dressing grinding wheels.

3. Gear hobbing

Belonging to the generating method of processing, its working principle is equivalent to the meshing of a pair of helical gears. The prototype of the gear hob is a helical gear with a large helix angle. Due to the few number of teeth (usually z = 1), the teeth are long and wrapped around the shaft to form a worm with a small helix angle. After grooving and cutting teeth, it becomes a hob with cutting edges and back angles.

4. Gear shaving

In mass production, gear shaving is a common precision machining method for non-quenched gear surfaces. Its working principle is to use the free meshing movement between the shaving cutter and the workpiece gear, and with the relative sliding between them, very fine chips are shaved off from the tooth surface to improve the accuracy of the tooth surface. Gear shaving can also form a crowning gear to improve the position of the tooth contact area.

5. Gear hobbing

Besides gear hobbing, gear hobbing is another commonly used tooth cutting process using the generating method. During gear hobbing, the hobbing cutter and the workpiece are equivalent to a pair of cylindrical gears meshing. The reciprocating motion of the hobbing cutter is the main motion of hobbing, while the circular motion of the hobbing cutter with the workpiece in a certain proportional relationship is the feed motion of hobbing.

6. Generating method grinding

The cutting motion of generating method grinding is similar to gear hobbing, which is a precision machining method for gear profiles, especially for hardened gears, and often the only precision machining method. Generating method grinding can be performed with worm grinding wheels, as well as with conical or disc-shaped grinding wheels.

7. Gear honing

The principle of gear honing is similar to gear shaving. The honing wheel and the workpiece are similar to a pair of helical gears with no backlash engagement. By utilizing the relative sliding at the engagement point and applying a certain pressure between the tooth surfaces, gear honing is performed.

8. Electrical discharge wire cutting

Electrical discharge wire cutting, abbreviated as wire cutting, has developed based on electrical discharge piercing and forming. It not only advances the application of electrical discharge machining but also in some aspects has replaced electrical discharge piercing and forming.