After completion of one or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and gear rack for Machine Tool Industry indexed back again to its starting position, thus enabling a short rack cutter of a practical duration to be utilized. Cutter is again fed back again to depth and routine is repeated. Number of teeth is controlled by the device gearing, and pitch and pressure position by the rack cutter. This technique is utilized for generation of exterior spur gears, being ideally suited for cutting large, dual helical gears. For creating helical the teeth, the cutter slides tend at the apparatus tooth helix angle.
The hob is fed into the gear blank to the correct depth and both are rotated together as though in mesh. The teeth of the hob cut into the function piece in successive purchase and each in a slightly different position. Each hob tooth cuts its own profile depending on the form of cutter , but the accumulation of these straight cuts produces a curved type of the gear teeth, hence the name generating procedure. One rotation of the work completes the trimming upto specific depth upto which hob is usually 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 to cut bevel-gear teeth. It isn’t widely used at the moment.
In gear planing process, the cutter consists of accurate involute rack which reciprocates across the face of the blank and the blank rotates in the correct relationship to the longitudinal motion of the cutter as if both roll together as a rack and pinion. Initially the cutter is certainly 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 finishing cuts are taken with single pointed tools. The utilization of the formed device for finishing can be 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, quantity of share to be taken out, and the kind of material.