After completion of 1 or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and indexed back to its starting position, thus allowing a brief rack cutter of a practical length to be utilized. Cutter is once again fed back again to depth and cycle is repeated. Amount of teeth is controlled by the gear rack for Machine Tool Industry china machine gearing, and pitch and pressure position by the rack cutter. This technique is used for generation of exterior spur gears, being preferably suited for cutting large, double helical gears. For making helical the teeth, the cutter slides tend at the apparatus tooth helix angle.
The hob is fed into the gear blank to the proper depth and both are rotated together as if in mesh. One’s teeth of the hob cut into the function piece in successive purchase and each in a slightly different placement. Each hob tooth cuts its profile based on the shape of cutter , but the accumulation of these straight cuts produces a curved type of the gear teeth, therefore the name generating process. One rotation of the task completes the reducing upto specific depth upto which hob is definitely fed unless the gear includes a wide face.
This methodis specially adopted to cutting large teeth which are hard to cut by formed cutter, and to cut bevel-gear teeth. It is not widely used at present.
In gear planing process, the cutter includes accurate involute rack which reciprocates across the face of the blank and the blank rotates in the right relationship to the longitudinal movement of the cutter as if both roll jointly as a rack and pinion. At first the cutter is definitely fed into complete tooth depth with cutter reciprocating and blank stationary. Involute form is generated as the blank rotates and involute rack cutter feeds longitudinally.
In the other method, both roughening and finishing cuts are taken with single pointed tools. The utilization of the formed device for finishing can be impracticable for the bigger pitches which are completed by a single pointed tool. The number of cuts required depends upon how big is the tooth, quantity of share to be removed, and the type of material.