Rotary having cutter are high-precision. hardened and ground, high-speed steel generat- ing tools held to Class A and AA tolerances in all principle elements . The gashe in the having cutter extend 'the fun length of the tooth, terminating in a clearance space at the bottom. The e clearance spaces provide unre- stricted channel for a constant flow of coolant to promptly di pose of chips. They also permit uniform depth of serration penetration and in- crease cutter life. The shaving cutter i rotated at high speeds up to 122m (400 and more surface ft.) per minute. Fig. 1.3- Ex~.ernal shaver wHit internal. cutter headattachment, Feed is fine and the tool contact zone is re- stricted. Cutter life depends on . everal factor : operating peed. feed ..material and hardne s of the work gear, its required tolerances, type of coolant, and the size ratio of culler to work gear. Design - Rotary gear shaving cutters are de- signed much like other helical involute gears. The serrations on the tooth profiles, in conjunc- tion with the crossing of the axes of the cutter and the work gear, make it a cutting tool. In design- ing rotary gear shaving cutters, the following are some of the points that must be considered:
I. Normal diametral pitch and normal pres- sure angle must be the same as those of the gears to be shaved.
2. Helix angle is chosen to give a desired crossed axis angle between the cutter and work. The crossed axis angle is the difference between the helix angles of the shaving cutter and work gear. The desired range is from 5 to 1.5°.