Optimisation of ultrasonic machining of zirconia bio-ceramics using genetic algorithm

Ultrasonic machining is one of the most extensively used non-traditional machining processes for the machining of non-conductive, brittle materials such as carbides, glasses and bio-ceramics. The present paper includes the investigation into surface roughness of machined of hexagonal holes and material removal rate during ultrasonic machining of zirconia bio-ceramics. The response surface methodology was employed for developing empirical models. Abrasive grit size, abrasive slurry concentration, power rating and tool feed rate have been considered as controlling parameters of ultrasonic machining process. Multi-objective optimisation has been carried out for minimising surface roughness of hole surface and maximising material removal rate during hexagonal profile generation by USM. However, for searching out the best optimal solution, genetic algorithm (GA) is used. Unlike traditional optimisation techniques, GA is strong and performs well in multi objective optimisation problems. Using genetic algorithm, maximum MRR of 0.2365 g/min and minimum surface roughness of 0.58 µm were obtained at the optimal parametric combination such as abrasive grit size of 57 µm, abrasive slurry concentration of 42 g/l, power rating of 492 W and tool feed rate of 0.88 mm/min.