Nano-finishing of BK7 optical glass using magnetic abrasive finishing process

BK7 is an optical glass extensively used in lens manufacturing. In this work, magnetic abrasive finishing (MAF) method was utilized for finishing of this hard-to-machine material and the effect of various process parameters on surface roughness was investigated using response surface methodology. The best surface roughness value achieved was 23 nm. Among various finishing parameters, the abrasive size was found to be the most significant parameter followed by machining gap, magnetic particles size, rotational speed, and percentage weight of binding agent. Also, the mechanisms of material removal were studied by using atomic force microscopy (AFM). The AFM observations revealed that both microcutting and microfracture mechanisms might exist during MAF of brittle materials depending on the finishing conditions. (C) 2015 Optical Society of America