has recently demonstrated a deterministic microgrinding process
that replaces the iterative conventional grinding and polishing
sequence suggested by the manufacturer. It may even eliminate
the need for polishing in some applications. COM's deterministic
microgrinding process is able to achieve optical quality surfaces
on Stavax® in minutes instead of days.
example of the process potential is presented in Figure 2.
A 70 mm convex radius was microground onto each of several
28 mm diameter hardened and tempered Stavax® tool inserts
provided by Opkor,
Inc. The extraordinary finishes were achieved on the OptiPro
SX50 using Lunzer Inc. metal-bonded CBN (cubic boron nitride)
ring tools (32 mm inner diameter, 4 mm wall thickness). The
three step process (rough grit: 65 µm, medium grit:
6-12 µm, fine grit: 2-4 µm), at a tool spindle
speed of 9,560 rpm and a work spindle speed of 135 rpm, required
a total process time of 30 minutes.
microgrinding, the final surface finish quality was examined
on the Zygo NewView® 200. As can be seen in Figure 2,
the surface has a very uniform finish quality. The surface
roughness for the test samples typically ran between 20-30
Å rms. The surface figure error was under 1 wave p-v.
with any initial development, it is likely that the process
could be further refined and that the results could be improved.
In addition to saving significant time and grinding cost,
the deterministic microgrinding technique will substantially
reduce final polishing time and could potentially eliminate
it. After processing, check to be certain that the surface
hardness was not compromised.
Van Gee developed the initial process.
For more detail, please contact:
from the July/August 1998 issue of Convergence