Advanced Optical Technologies recently published a paper co-authored by FISBA’s Senior Expert Optical Fabrication Technology, Oliver Fähnle.
The paper, titled “Analysis of critical process parameters of ductile mode grinding of brittle materials”, can be accessed online here.
The process of ductile mode grinding has been analyzed experimentally. Besides the traditional approach, controlling the depth of a cut on feed-controlled ultra-precision machines (UPMs), two alternative approaches have been tested. By applying fluid jet polishing (FJP) using a grinding slurry, a stable ductile mode grinding could be set up. Subsequently, loose abrasive grinding processes on load-controlled traditional spindle machines have been tested to be suited for ductile mode grinding identifying the dependence of crack initiation on the type of slurry fluid being applied. In that way, substantially improved levels of surface roughness could be achieved, although local brittle cracking within the generated clear apertures still remained. Furthermore, critical process parameters were identified determining the process window of feed-controlled ductile grinding applied on state-of-the-art UPM machineries. These have been analyzed experimentally, and it was found that the critical depth of a cut significantly depends on the set of critical process parameters being applied. Finally, the critical ductile grinding process parameters could be identified determining the generated level of surface roughness achieving 0.83 nm Ra on tungsten carbide. Access full article.