After completion of 1 or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and indexed back again to its starting position, thus allowing a brief rack cutter of a practical length to be utilized. Cutter is again fed back to depth and routine is repeated. Amount of teeth is controlled by the device gearing, and pitch and pressure position by the rack cutter. This method is used for generation of exterior spur gears, being preferably fitted to cutting large, double helical gears. For making helical tooth, the cutter slides are inclined at the apparatus 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. The teeth of the hob cut in to the function piece in successive purchase and each in a slightly different position. Each hob tooth cuts its own profile based on the shape of cutter , but the accumulation of these straight cuts generates a curved kind of the gear teeth, thus the name generating process. One rotation of the work completes the trimming upto specific depth upto which hob can be fed unless the gear has 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 isn’t widely used at present.
In gear planing procedure, the cutter consists of true involute rack which gear rack for Machine Tool Industry china 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 with each other 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 method, both 
roughening and finishing cuts are taken with single pointed tools. The use of the formed device for finishing is usually impracticable for the bigger pitches which are completed by a single pointed tool. The number of cuts required is dependent upon the size of the tooth, amount of share to be taken out, and the kind of material.