Polishing abrasives that have been bound in a solid matrix can offer several potential advantages over loose abrasive processes with pitch or polyurethane laps for finishing of optics. These advantages include polishing efficiency, temperature stability, cost of consumables, and compatibility with CNC generating machines. Unfortunately, little has been published on bound- abrasive polishers, and very few commercially available products exist.

Custom-manufactured polishing laps are used to study material removal for transparent ceramics as a function of load, coolant, and lap composition.

There are four performance criteria for the successful development of a bound abrasive polisher:

1) The polisher must maintain its physical integrity during use at moderate to high velocities (thousands of rpm), in an aqueous environment, and under light to moderate load;

2) The polisher must release particles of polishing abrasive at a rate that promotes efficient removal of glass from the work piece surface, but not so rapidly as to cause excessive tool wear, or so slowly that the tool surface "glazes" over with a solid film of binder;

3) The polisher must be manufactured in such a way that it exhibits reproducible performance under constant operating conditions;

4) The initial surface figure quality of the fine ground part must not be so severely degraded that it cannot be easily improved in fine finishing with processes like MRF.

We conduct research on compositions and manufacturing techniques for developing bound abrasive polishing tools. Our long term objective is to produce tools for use on COM CNC machines to remove grinding tool marks (e.g., cutter marks) on optical glass surfaces in a pre-polishing stage prior to fine finishing with MRF. Another objective is to eliminate sub-surface damage and pitting from deterministically micro-ground polycrystalline optical ceramics like ALON and spinel. Our strategy is to conduct screening experiments manually with pin laps and/or pellet laps on candidate systems (polisher abrasive and epoxy host, part type/shape-flat, coolant type, and load), followed by the manufacture and testing of contour or peripheral ring tools using CNC machine platforms.

	Pyramidal alumina pin lap (far left), and a square-faceted epoxy lap (left) filled with nanodiamonds and alumina. Grain decoration on the surface of an ALON part (below).

L. L. Gregg, A. E. Marino, J. C. Hayes, and S. D. Jacobs ,“Study of Grain Decoration in ALON Using Bound Abrasive Polishers,” in Optical Manufacturing and Testing V , edited by H. P. Stahl (SPIE, Bellingham, WA, 2003), Vol. 5180, pp. 47-63.

B. E. Gillman and S. D. Jacobs, "Bound-Abrasive Polishers for Optical Glass," Appl. Opt. 37, 3498-3505 (1998).

B. E. Puchebner and S. D. Jacobs, "Development of New Bound Abrasive Polishers for Final Finishing of Optical Glasses," in Optical Manufacturing and Testing, V. J. Doherty and H. P. Stahl, eds., Proc. SPIE 2536, 256-264 (1995).

W. Ng et al., "Evaluation of Bound Abrasive Media for Fabrication of Ring Tool Polishers," in Optical Fabrication and Testing, Vol. 13, 1994 OSA Technical Digest Series (Optical Society of America, Washington, DC, 1994), pp. 114-116.