Multi-objective Optimization for Ultrasonic Drilling of GFRP Using Grey Relational Analysis

For machining of brittle materials like glass, ceramics etc., ultrasonic machining has become very popular. Number of engineering and common applications require use of glass fiber reinforced plastic (GFRP) and it is essential to machine features in this material for use. In this work, full factorial design of experiments (DoE) based investigation is conducted to study the effect of process parameters on ultrasonic drilling of GFRP. The control parameters selected include amplitude, pressure and thickness of the GFRP sheet being machined. Three levels of each of these parameters are selected giving 33 = 27 trials. The material removal rate (MRR), overcut (OC), taper, top delamination and bottom delamination produced on the GFRP while slitting are measured as response parameters. Ultrasonic machining has number of process parameters and is not a simple process to control and get desired machining results. Grey relational analysis is applied to the experimental data to obtain the best combination of input parameters for different cutting conditions like roughing, semi-finishing and finishing. Parameter combinations are given grades using grey relational analysis (GRA) process and the optimum combination is suggested for various requirements of machining in terms of roughing, semi-finishing and finishing.