Abstract

Metallic grinding tools have been designed which behave similarly to unstable hydrodynamically lubricated bearings. Tool suspension geometry has been arranged so that negative angles of attack occur when the tool traverses a workpiece using a viscous slurry of diamonds in the micrometer size ranges. The negative attack angle causes a large suction pressure equal to the vapor pressure of the slurry between the tool and the workpiece. Under proper conditions, the tool force is independent of velocity, and the pressure is independent of the tool contact area. The result is a tool that works completely to edges without roll off, and which is suitable for working lightweight waffle structures without print-through. The grinding rates obtained are comparable to those obtained with #100 silicon carbide at the same velocity. A specular surface finish is produced which is suitable for interferometry. The tools have been used to surface a square mirror, and an off-axis parabola of lightweight construction. An optician working by hand, has been able to remove 7 µm per hour on a 0.75 m² pie-shaped optic. The principal application problems concern the large lateral shear forces produced on lightweight structures, and the possibility of inclusions in the tool metal causing occasional scratches.

© 1990 Optical Society of America