After completion of 1 or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and indexed back to its starting position, thus allowing a brief rack cutter of a practical duration to be utilized.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 method is utilized for generation of external spur gears, being preferably fitted to cutting large, dual helical gears. For creating helical the teeth, the cutter slides are inclined at the apparatus tooth helix angle.
The hob is fed in to the gear blank to the proper depth and both are rotated together as though 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 own profile depending on the form of cutter , however the accumulation of these directly cuts creates a curved type of the gear teeth, hence the name generating process. One rotation of the task completes the reducing upto particular depth upto which hob is definitely 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 is not widely used at present.
In gear planing procedure, the cutter contains 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 though both roll with each other as a rack and pinion. At first the cutter is certainly fed into full 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 finishing cuts are taken with single pointed tools. The use of the formed device for finishing can be impracticable for the bigger gear rack for Machine Tool Industry pitches which are finished by a single pointed tool. The amount of cuts required is dependent upon the size of the tooth, quantity of stock to be taken out, and the type of material.