After completion of 1 or two teeth, the blank and gear rack for Machine Tool Industry china cutter stop feeding and the cutter is withdrawn and indexed back again to its starting position, thus allowing a short rack cutter of a practical size to be used. Cutter is again fed back again to depth and routine is repeated. Number of teeth is managed by the device gearing, and pitch and pressure angle by the rack cutter. This method can be used for generation of exterior spur gears, being preferably suited for cutting large, double helical gears. For generating helical tooth, the cutter slides tend 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 if in mesh. One’s teeth of the hob cut in to the function piece in successive order and each in a slightly different placement. Each hob tooth cuts its profile depending on the shape of cutter , but the accumulation of these straight cuts creates a curved form of the gear teeth, therefore the name generating process. One rotation of the work completes the reducing upto specific depth upto which hob is usually fed unless the gear has a wide face.
This methodis specifically 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 present.
In gear planing process, the cutter consists of accurate involute rack which reciprocates over the face of the blank and the blank rotates in the right relationship to the longitudinal movement of the cutter as though both roll collectively as a rack and pinion. At first the cutter is certainly fed into complete 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 completing cuts are taken with single pointed tools. The use of the formed device for finishing is definitely impracticable for the larger pitches which are finished by an individual pointed tool. The number of cuts required depends upon how big is the tooth, amount of stock to be taken out, and the type of material.