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the cutter is withdrawn and indexed back to its starting position, thus allowing a short rack cutter of a practical duration to be utilized. Cutter is again fed back again to depth and cycle is repeated. Amount of teeth is controlled by the machine gearing, and pitch and pressure position by the rack cutter. This method is utilized for generation of external spur gears, being ideally fitted to cutting large, dual helical gears. For producing helical tooth, the cutter slides are inclined at the apparatus tooth helix angle.
The hob is fed into the gear blank to the correct depth and the two are rotated together as though in mesh. The teeth of the hob cut in to the function piece in successive purchase and each in a somewhat different position. Each hob tooth cuts its own profile depending on the shape of cutter , but the accumulation of these directly cuts produces a curved form of the gear teeth, hence the name generating process. One rotation of the task completes the trimming upto particular depth upto which hob is definitely fed unless the gear includes a wide face.
This methodis specially adopted to cutting large teeth which are challenging to cut by formed cutter, and also to cut bevel-gear teeth. It isn’t widely used at present.
In gear gear rack for Machine Tool Industry planing procedure, the cutter contains 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 if both roll together as a rack and pinion. At first the cutter is usually fed into full 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 technique, both roughening and finishing cuts are taken with single pointed tools. The usage of the formed tool for finishing can be impracticable for the bigger pitches which are completed by an individual pointed tool. The number of cuts required is dependent upon how big is the tooth, amount of share to be removed, and the kind of material.
