An experimental investigation on the influence of machining parameters on surface finish in diamond turning of silicon optics

Silicon is widely used in IR optics, X-Ray optics and electronics applications. These applications require Silicon of optical quality surface as well as good form accuracy. To get the desired finish and dimensional accuracy, diamond turning is preferable. Taylor-Hobson Nanoform-250 diamond turning equipment is used to machine flat Silicon mirror. Negative rake diamond tool is used with a tool nose radius of 1.5 mm. A series of SPDT machining operations are performed in the sequential combinations of tool feed rate, Spindle Speed and depth of cut. In order to find out the effect of machining parameters on the Surface Roughness during turning, Response Surface Methodology (RSM) is used and a prediction model is developed related to average Surface Roughness (Ra) using experimental data. The surface quality is analyzed in terms of arithmetic roughness (Ra) and Power Spectral Density for uniform evaluation. In addition, a good agreement between the predicted and measured Surface Roughness is observed.