Page 336 - Gear Technology Solutions

angle. The inside blade top and the outside blade top match the average tooth
root in Figure 4. The term average tooth root indicates that the real root moves
from the outside blade top to the inside blade top location in direction of the
gear rotation vector.

23.4 Top Slope and Stepping of Cutter Blades for Face Milled
Pinions and Gears

In generated and Formate face milling processes, stepping of the blades is not
used. The major reason is the fact that the tip reference points are significantly
closer together as compared to the blade tip reference point distance in a face
hobbing cutter. In connection with Figure 5, it will be explained in the following
section why only using a top slope angle on inside and outside blades delivers
the perfect solution for pinions and generated or Formate gears.

Figure 5: Top slope angle for all face milled members

The cutter head tilt in the face milling process moved the cutter at the opposite
side of the cut away from the part. This tilt reduces the natural length crowning
caused by duplex taper root angle reduction. Because the values of length
crowning reducing cutter head tilt are rather large, the required amounts are
commonly split between pinion and gear. This practice makes it necessary to
apply top slope angles to face milled pinions and gears.

321