Optimization of process parameters with Taguchi method for nano machining CaF2 crystal

Abstract

ABSTRACTOwing to the outstanding optical characteristics of calcium fluoride (CaF2) crystal, this material is a great choice for ultraviolet lenses and windows. Due to its softness and brittleness, it is difficult to nano machining CaF2 crystal. Fixed abrasive polishing technology, one of nano machining directions, was adopted to process CaF2 crystal. Experiments were designed using Taguchi method to explore the effect of pressure, plate speed, slurry flux and slurry pH on material removal rate and surface roughness in fixed abrasive polishing of CaF2 crystal. The optimum polishing parameters for material removal rate are discovered to be pressure 10 kPa, slurry pH 11, plate speed 50 rpm and slurry flux 40 ml/min. And they are pressure 6.7 kPa, slurry pH 9, plate speed 40 rpm and slurry flux 60 ml/min for surface roughness. The analysis of variance shows that pressure 52.6% and plate speed 25.4% are the most significant parameters that affect material removal rate, while plate speed 51.3% and slurry flux 32.0% are the two main factors for surface roughness. The most significant factor and the contribution of each parameter for MRR and surface roughness were obtained in nano machining process, respectively.