Loading when grinding cermets

Dear Doc: I grind cermets and experience massive loading. Any ideas how to overcome that?

The Doc Replies: Assuming you’re using the right wheel (small grit size, friable grit) and the right parameters (low material-removal rates, low wheel speeds), first match the coolant velocity to the wheel velocity to reduce the rate of loading. Then, stick the wheel frequently to clear loading that does accumulate. If that still doesn’t do the trick, install a small-orifice-area, high-pressure cleaning nozzle.

Courtesy of J. Badger

Figure 1: When grinding with the wheel face, the aggressiveness is high and the corner breaks down quickly, which is good because the contact area is much larger.

Dear Doc: I grind with the wheel face and eventually get a taper. Once I get the taper, a fine surface finish is hard to achieve. What is your recommendation?

The Doc Replies: When grinding with the face of the wheel, the aggressiveness is high and the corner breaks down quickly. That’s good, because now the contact area is much larger and you can remove material quicker (Figure 1). However, only the tail end of the fully developed taper cleans the surface finish.

The solution is to dress a taper in the wheel. That way you start with the taper and control its shape. What’s more, you can put a flat in the end to clean the surface finish at the end of the cut. You also eliminate having to scrap parts until the taper breaks in.