SECTION 5.4

As discussed earlier, there is a general practice which can be altered to suit each particular situation in determining when a broach tool should be pulled for sharpening. The basic spline tooth tends to have a greater corner breakdown than the wear directly along the cutting edge (see Figure 5-2). When a tool has more than the 0.003" to 0.005" corner breakdown, an O. D. or top grind is recommended.

Figure 5-2.
A view of a spline tooth showing a typical corner wear pattern.

This effectively removes the worn areas. If the broach tool is not sharpened properly and worn areas are not removed, the corners will break down further and wear back prematurely. Since part tolerances are usually limiting, the practice of O.D. or top sharpening must be done cautiously and sparingly