Effect of Drilling Conditions on Microwave-Metal Discharge during Microwave Drilling of Stainless Steel

Abstract

Processing of metallic materials using microwave energy offer benefits of time compression and energy saving during applications such as sintering, casting, melting, joining and cladding. However, use of microwave energy is uncommon for machining of metallic materials because of high reflectivity. The present work aims to study microwave-metal (MW-m) discharge-induced plasma channel (PC) characteristics during microwave drilling of thin stainless steel (SS) sheet (0.6 mm) at 2.45 GHz. Experimental trials inside two different microwave applicators A1 and A2 were monitored and recorded. The images of the plasma channel generated in both the microwave applicators were obtained at different time intervals to analyze the plasma channel diameter (PCD). Experimental results revealed that variation in the microwave power significantly affects the dimension of plasma channel generated in the tool-work gap and heat affected zone (HAZ) formed around the drilling zone. Reduction in microwave drilling time of approximately 80% was observed at 3 kW power compared to drilling time at 0.7 kW power. The HAZ observed in the samples drilled at 0.7 kW was significantly higher than the HAZ observed at 3 kW owing to higher drilling time of samples at 0.7 kW.