STUDY ON ULTRA HIGH SPEED MICRO DRILLING OF HARD COMPOSIT

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In this study. an ultra high speed micro drilling system was made by using a precision X-Y servo driving table.The glass epoxy print circuit board(PCB) was drilled by the above system under various drilling conditions. The drilling performances of HSS drills with 40-100 mum in diameter were tested under dry and wet conditions. As the results, it was shown that the drill feed rate 2 IOTAm /rev with higher drill speed under wet condition was suitable for micro drilling of PCB.Stepping feed also gave good results. The effect of oil supply on micro drilling operations was very significant. Especially, the oil supply was very effective to reduce the torque which is the main cause of micro drill damage and lower tool life. The sintered carbide drill resulted in longer tool life and higher quality of drilled hole surfaces and In reducing the bar due to lower tool wear. Oil mist application was also very effective to improve the micro drilling performance. As the result of this study, it was made clear that the ultra high speed micro drilling with sintered carbide tool was effective to drill out many micro hole S on PCB under oil mist conditions.