The Process Of Gear Shaving

- Aug 01, 2018 -

Gear shaving is a free-cutting gear finishing operation which removes small. amounts of metal from the working sur- faces of the gear teeth. Its purpose is to correct errors in in- dex, helical angle, tooth profile and eccentricity. The pro- cess can also improve tooth surface finish and eliminate, by crowned tooth forms, the danger of tooth end load concen- trations in service. Shaving provides for form modifications that reduce gear noise. These modifications can also increase the gear's load carrying capacity, its factor of safety and its service lire. Gear finishing (shaving) is not to be confused with gear cutting, (roughing). They are essentially different. Any machine designed primarily for one cannot be expected to do both with equal effectiveness, or equal economy. Gear shaving is the logical remedy for the inaccuracies in- herent in gear cutting. It is equally effective as a control for these troublesome distortions caused by heat treatment. The form of the shaving cutters can be re-ground to make crown and profile alJowance for different heat treatment movements due to varying heats of steel. The gear shaving machine can also be reset to make allowance for lead change in heat treatment. The gear shaving process can be performed at a high pro- duction rate. Machines are available to shave external spur or helical gears up to 180" in diameter. Other machines are also available for internal spur or helical gears. For best results of shaving, the hardness of the gear should not exceed 30-32 Rc scale. When stock removal is kept to the recommended limits, and gears are properly qualified, the shaving process will finish gear teeth in the 7 to 10 pitch range to the following accuracies: involute profile .0002; tooth-to-tooth spacing.0003; lead or parallelism .0002. ]n any event, it should be remembered that gear shaving can remove 65 to 80% of the errors in the nabbed or shaped gear. It will make Q good gear better. The quality of tile shaved gear ls dependent to a large degree upon havillg good hobbed OT shaped gear teeth.