Theoretical and experimental studies on localized electric field during microwave drilling of metals

Microwave drilling (MWD) is a nontraditional machining process. To further reveal the mechanism of the MWD of metals, a physical model of the electric field during the MWD was established and mathematically solved. Microwave drilling experiments were performed, and an ultra-depth microscope was used to investigate MWD morphologies under different conditions (gap scale d and tip radius R). By comparing the characteristics of the MWD morphology and the distributions of electric field strength, the relationship between the MWD morphology characteristics and electric field strength distribution on the workpiece was revealed. The effects of the gap scale d and tip radius R on the MWD morphology and electric field strength distributions were also analyzed. The results of this study can be helpful in enhancing the understanding of the MWD mechanism and the prediction of machining accuracy and surface quality.