Process parameters optimisation for Si3N4 in chemical-mechanical polishing via Taguchi technique

By applying chemical-mechanical polishing (CMP) technique to high precision processing of rotary curved surface workpieces of silicon nitride (Si3N4) ceramic, a CMP experimental device was established on a numerical control (NC) jig grinder. Using Taguchi robust design method, through signal to noise ratios (S/N ratios) and analysis of variance, the influence of slurry concentration, slurry flow rate and polishing wheel speed on surface roughness was analysed. With the increase of polishing wheel speed, the surface roughness Ra increased. The optimal process parameters of CMP on rotary curved surface workpieces of Si3N4 ceramic were selected: slurry concentration of 20%, polishing wheel speed of 6,000 r/min, and slurry flow rate of 0.6 L/min. The result showed that the descending order of selected process parameters impacting on surface roughness was polishing wheel speed, slurry flow rate and slurry concentration.