When it comes to precision ceramics and other project-finishing items, a good lapping plate and a diamond lapping process can make all the difference. Lapping is the machining process that rubs two surfaces together using an abrasive to grind or polish. In diamond lapping, the abrasive used is diamonds.
If you are looking for edge-to-edge flatness then diamond lapping, which routinely offers sublight band (11 millionths of an inch) results and can offer up to 1/20 wavelength under specific conditions, is the best option. A high down-pressure or down-force of five psi or up is best to fully leverage the strength of diamond on ceramic. The lapping machine should also a tough drive system to tolerate the pressure, and a variable speed drive with high top-end RPM capability. Accurate interferometry combined with specialized polishing machines or skilled hand polishing can produce surfaces flatter than 30 nanometers.
In comparison to conventional abrasives, diamonds provided the best results for alumina wafer, eliminating hand-polishing, reducing the cycle time by 30 minutes and reducing cleaning time. It also saved $14.87 per hour in slurry costs and reduced waste and associated disposal costs, according to one study.
Very small items of 3″ down to a few millimeters, can be handled with the use of a lapping jig to hold the material while it is lapped. This allows precise control of the orientation of the specimen to the lapping plate as well as fine adjustment.
