Ultrasonic cavitation and vibration hybrid-assisted micro-drilling of stainless steel

Abstract

The ultrasonic cavitation and vibration hybrid-assisted micro-drilling method is proposed to improve the micro-drilling performance of difficult-to-machine materials such as stainless steel. The mechanism of ultrasonic cavitation and vibration hybrid micro-drilling is investigated by performing the comparison tests of conventional micro-drilling (CD), ultrasonic vibration micro-drilling (UVD), ultrasonic cavitation micro-drilling (UCD), and hybrid micro-drilling (HD), and the effects of ultrasonic cavitation and vibration on stainless steel during micro-drilling process are analyzed considering the chip morphology, thrust force, tool wear, and micro-hole quality. Experimental results show that both CD and UVD produce strip-shaped chips, and the chips in UVD is much shorter than that in CD. However, the chips in UCD and HD are mostly fragmented short chips with a very small length ranging from tens to hundreds of microns. When drilling to the same number of holes, the thrust force, and micro-hole roundness error in UVD, UCD, and HD are less than that in CD; especially, those in HD are the smallest. Moreover, the tool wear in HD is also smaller than the other three processes. Thus, the HD method can effectively improve the chip breaking ability, greatly reduce the thrust force and extend the tool life, and the best processing quality of micro-hole is obtained by HD. The ultrasonic cavitation and vibration hybrid-assisted micro-drilling is demonstrated to effectively improve the micro-drilling performance of stainless steel.