Multi Response Optimization of Nd:YAG Laser Micro Drilling Characteristics of 304 Stainless Steel using Desirability Function Approach

Abstract

Laser micro drilling is a non-traditional machining process for producing micro hole of various sizes and different angle in many modern industrial application, such as aerospace gas turbine, automobile industry, electronics field etc. Laser drilling is extremely high speed with high aspect ratio. However, the quality and accuracy of the holes can be excellent, if the optimal process parameter has set. It is difficult to achieve exact size of hole as per suggested by the equipment manufacturer without any consideration. So this paper addressed to investigate influence of process parameter on drilling characteristics of 304 stainless steel of 1.5 mm thickness material using Nd:YAG laser drilling through desirability function optimization technique. The effect of process parameter taken during machining operation is average power, nozzle stand-off, nitrogen gas pressure to obtain requisite hole quality. The output responses are entry circularity, exit circularity and taper angle were considered performance criteria for the experimentation. Analysis of variance (ANOVA) has been performed to find out the significant process parameter during the micro drilling process. It is found that nitrogen gas pressure is highly influencing factor on the overall response characteristics, which is about 54.62% and nozzle standoff is 2nd highest influencing parameter, which is about 27.69%.