Machining parameters optimization on micro hole vibration drilling using grey system theory

The grey system theory is a new technique for performing prediction, relational analysis, and decision making in many areas. In this paper, grey relational analysis was used to optimize the machining parameters with multiple performance characteristics in micro hole vibration drilling. Experiments were conducted on a computer numerical control vertical machining centre and L9 orthogonal array was chosen for the experiments. The drilling parameters namely the vibration frequency, amplitude, feed and spindle speed were optimized based on the multiple performance characteristics including the positional error, aperture error, and burr height. Optimal machining parameters were determined by the grey relational grade obtained from the grey relational analysis. The experimental results show that the vibration frequency is the most significant factor which affects the micro hole vibration drilling and the performance in the drilling process can be effectively improved through the new approach. Confirmation tests verify that the optimal combination of the vibration drilling parameters can reduce the positional error, the aperture error, and the burr height.