After completion of one or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and indexed back again to its starting position, thus enabling a brief rack cutter of a practical length to be utilized. Cutter is again fed back to depth and cycle is repeated. Quantity of teeth is controlled by the device gearing, and pitch and pressure angle by the rack cutter. This technique is utilized for generation of exterior spur gears, being preferably suited for cutting large, double helical gears. For making helical tooth, the cutter slides tend at the gear tooth helix angle.
The hob is fed into the gear blank to the correct depth and both are rotated together as if in mesh. One’s teeth of the hob cut in to the function piece in successive purchase and each in a slightly different placement. Each hob tooth cuts its profile based on the form 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 slicing upto particular depth upto which hob is definitely fed unless the apparatus has a wide face.
This methodis specifically adopted to cutting large teeth which are hard to cut by formed cutter, and to cut bevel-gear teeth. It is not widely used at the moment.
In gear planing process, the cutter gear rack for Machine Tool Industry china includes true 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 collectively as a rack and pinion. Initially the cutter is definitely fed into complete tooth depth with cutter reciprocating and blank stationary. Involute form is produced 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 use of the formed tool for finishing can be impracticable for the larger pitches which are finished by a single pointed tool. The amount of cuts required is dependent upon how big is the tooth, quantity of share to be removed, and the type of material.