Grinding with a taper

Dear Doc: We cylindrical-traverse-grind long steel parts. We must follow a specification from 1970 that stipulates “traverse maximum one-eighth of the wheel width per workpiece revolution,” which is contrary to what you preach regarding using almost the entire wheel width during rough grinding. Is there something we can do? Our cycle times are eight to 12 hours.

The Doc replies: Yes. You can dress a taper into your wheel.

Currently, with your overlap ratio of 8.0, one-eighth of the wheel is doing almost 100% of the work, and seven-eighths of the wheel basically is “sparking out” with a depth of cut close to zero. That’s fine for finishing grinding but silly for rough grinding. Use almost the entire wheel. That’s why it’s there.

But you can’t do that. You’re stuck using one-eighth of the wheel. So here’s what we can do to use almost all the wheel for roughing and still honor that specification: Dress a taper into the wheel.

Dress a flat into one-eighth of the wheel and a taper into the remaining seven-eighths. The taper height should be slightly higher than your DOC — say 120%. This is akin to cylindrical peel grinding.

The formula is tangent(taper-angle) = taper-height/taper-width. In the situation in the figure, that’s 0.05 degree.

Dressing a taper in a wheel allows you to use almost the entire wheel for roughing. Image courtesy of J. Badger

That’s not much of an angle, but it’s enough to shift the grinding action to the taper. It might be tricky to program your machine to dress in such a small angle. If so, you also could dress in a series of steps as shown in (c).