In the manufacture of bevel gears, the gear blanks are first being pre-formed through forging or casting and then followed by machining to desired dimensions using lathes or by a special machine specially designed for the task. The teeth are then produced in the gear blank by machining. The form of the teeth and the volume of production are what dictates the type of machining and machine tool to be used in creating the gear. In this case, the following guidelines are usually considered when machining straight toothed bevel gears.
In forming through a milling cutter, the process involves low productivity and quality, making it suitable for productions that require less volume and precision.
In generation process, there is high accuracy and finish which is applicable to mass manufacturing. During this process, the internal flanks of two teeth of straight toothed bevel gear adjacent to each other are created with an involute profile of the cutting edges that are rotating as they cut through the gear blank.
It is worth noting at this point that the teeth of hypoid and spiral bevel gears are created by a very similar generation process with the cutters resembling the face of milling cutter. In order for both gears to have good performance, last longer, and run smooth, they need to have a high surface finish and to be accurate in forms and dimensions. More importantly, they need to be wear-resistant that can be achieved through the employment of gear teeth finishing that could be done right after almost precise pre-forming and machining.
Typically, smaller gears that are created through cold rolling don’t need additional finishing works. In case, they do, a little bit of finishing might be enough such as lapping right after the hardening process. But if you need machined and hardened bevel gears, then they are most likely need to be finished for high accuracy.
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