After completion of one or two teeth, the blank and gear rack for Machine Tool Industry china Cutter stop feeding and the cutter is withdrawn and indexed back again to its starting position, thus allowing a brief rack cutter of a practical length to be utilized.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 once again fed back again to depth and cycle is repeated. Quantity of teeth is managed 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 suited for cutting large, double helical gears. For producing helical teeth, the cutter slides tend at the gear tooth helix angle.
The hob is fed into the gear blank to the proper depth and the two are rotated together as if in mesh. The teeth of the hob cut in to the work piece in successive purchase and each in a somewhat different placement. Each hob tooth cuts its own profile based on the form of cutter , but the accumulation of these directly cuts creates a curved type of the gear teeth, therefore the name generating process. One rotation of the task completes the trimming upto specific depth upto which hob is fed unless the gear has 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 is not widely used at present.
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 right relationship to the longitudinal motion of the cutter as if both roll together as a rack and pinion. At first 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 technique, both roughening and finishing cuts are taken with single pointed tools. The utilization of the formed tool for finishing is certainly impracticable for the bigger pitches which are completed by a single pointed tool. The amount of cuts required is dependent upon how big is the tooth, quantity of stock to be eliminated, and the kind of material.