After completion of one or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and indexed back to its starting position, thus enabling a short rack cutter of a practical duration to be used. Cutter is once again fed back again to depth and routine is repeated. Amount of teeth is controlled by the machine gearing, and pitch and pressure position by the rack cutter. This technique can be used for generation of external spur gears, being preferably fitted to cutting large, dual helical gears. 
For generating helical tooth, the cutter slides tend at the gear tooth helix angle.
The hob is fed in to the gear blank to the correct depth and the two are rotated together as if in mesh. The teeth of the hob cut in to the work piece in successive order and each in a slightly different placement. Each hob tooth cuts its own profile depending on the shape of cutter , but the accumulation of these straight cuts produces a curved kind of the gear teeth, therefore the name generating procedure. One rotation of the task completes the slicing upto particular depth upto which hob can be fed unless the apparatus has a wide face.
This methodis gear rack for Machine Tool Industry specially adopted to cutting large teeth which are difficult to cut by formed cutter, and also to cut bevel-gear teeth. It is not widely used at present.
In gear planing procedure, the cutter consists of accurate involute rack which reciprocates over the face of the blank and the blank rotates in the right relationship to the longitudinal motion of the cutter as if both roll with each other as a rack and pinion. At first the cutter can be fed into complete tooth depth with cutter reciprocating and blank stationary. Involute shape is generated as the blank rotates and involute rack cutter feeds longitudinally.
In the other method, both roughening and completing cuts are taken with single pointed tools. The usage of the formed tool for finishing is definitely impracticable for the larger pitches which are completed by an individual pointed tool. The number of cuts required depends upon how big is the tooth, amount of share to be removed, and the kind of material.