After completion of 1 or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and indexed back to its starting position, thus allowing a short rack cutter of a practical size to be used. Cutter is again fed back to depth and cycle is repeated. Amount of teeth is managed by the device gearing, and pitch and pressure position by the rack cutter. This technique is utilized for generation of exterior spur gears, being preferably suited for cutting large, double helical gears. For generating helical the teeth, the cutter slides tend at the apparatus tooth helix angle.
The hob is fed in to the gear blank to the proper depth and both are rotated together as if in mesh. The teeth of the hob cut in to the function piece in successive order and each in a somewhat different gear rack for Machine Tool Industry placement. Each hob tooth cuts its own profile based on the form of cutter , however the accumulation of these straight cuts generates a curved kind of the gear teeth, thus the name generating process. One rotation of the task completes the trimming upto specific depth upto which hob is usually fed unless the apparatus has a wide face.
This methodis specially adopted to cutting large teeth which are tough to cut by formed cutter, and to cut bevel-gear teeth. It is not widely used at present.
In gear planing procedure, the cutter consists of true involute rack which reciprocates over the face of the blank and the blank rotates in the correct relationship to the longitudinal movement of the cutter as though both roll jointly as a rack and pinion. At first the cutter is fed into complete tooth depth with cutter reciprocating and blank stationary. Involute form is produced as the blank rotates and involute rack cutter feeds longitudinally.
In the other technique, both roughening and finishing cuts are taken with single pointed tools. The usage of the formed tool for finishing is definitely impracticable for the bigger pitches which are finished by an individual pointed tool. The number of cuts required depends upon the size of the tooth, amount of stock to be removed, and the kind of material.