Process optimisation in pulsed laser micromachining with applications in medical device manufacturing

Pulsed laser machining offers many unique capabilities that continuous-wave (CW) laser machining cannot. In pulsed laser machining, however, the additional process parameters of peak power, pulse frequency and pulse duration make it more difficult to find and fine tune a suitable operation window. This becomes harder in micromachining applications where tolerance of inaccuracy is smaller. How to determine these parameters in a systematic way is of great interest. This paper presents a hybrid approach, in which an analysis of the interactive reactions between various process parameters and their influence on machining quality if first conducted. Based on an energy balance as well as on the characteristics of pulsed laser machining, these relationships lead to the establishment of several guidelines. These guidelines are followed to determine an initial set of process parameters that are refined in the subsequent design of an experiment. The approach is followed in a precision medical device manufacturing case where a six-variable fractional factorial design with multiple responses is chosen to quantify the effects of key process parameters on visual and metallurgical responses.