After completion of 1 or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and indexed back to its starting position, thus enabling a short rack cutter of a practical length to be utilized. Cutter is once 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 can be used for generation of external spur gears, being ideally fitted to cutting large, dual helical gears. For producing helical teeth, the cutter slides tend at the gear tooth helix angle.
The hob is fed in to the gear blank to the correct depth and both are rotated together as though in mesh. One’s teeth of the hob cut into the function piece in successive purchase and each in a somewhat different placement. Each hob tooth cuts its profile depending on the form of cutter , but the accumulation of these straight cuts creates a curved kind of the gear teeth, therefore the name generating process. One rotation of the work completes the trimming upto certain depth upto which hob is usually fed gear rack for Machine Tool Industry china unless the gear includes a wide face.
This methodis specifically adopted to cutting large teeth which are tough to cut by formed cutter, and also to cut bevel-gear teeth. It is not widely used at the moment.
In gear planing process, the cutter contains accurate involute rack which reciprocates across the face of the blank and the blank rotates in the right relationship to the longitudinal motion of the cutter as if both roll collectively as a rack and pinion. Initially the cutter can be fed into complete tooth depth with cutter reciprocating and blank stationary. Involute shape is produced as the blank rotates and involute rack cutter feeds longitudinally.
In the other technique, both roughening and completing cuts are taken with single pointed tools. The utilization of the formed device for finishing is usually impracticable for the larger pitches which are completed by an individual pointed tool. The number of cuts required is dependent upon the size of the tooth, quantity of stock to be eliminated, and the kind of material.