Ultrasonic assistance in drilling: FEM analysis and experimental approaches

Conventional drilling (CD) which is known by two constant rotary and linear motions causes some problems in drilling of materials such as high thrust force, poor surface quality, and rapid tool wear. To get rid of these problems or at least minimize them, a promising technology has been employed in the recent years, where vibrations usually with low amplitude and high frequency are applied to the direction of feed motion results in a time-dependent velocity between drill tip and workpiece. This paper focuses on the design of a vibratory tool following by experimental and numerical approaches to study the influence of longitudinal ultrasonic vibrations on drilling of aluminum alloy 7075. Experimental part is a comprehensive exercise to design, fabricate, and test a system equipped with different instruments to work in desired conditions. Experimental results are supported by a finite element method to better comprehend what is happening in cutting process when ultrasonic vibrations are added. The achieved results prove that using ultrasonic-assisted drilling (UAD), the machining ability of drilled aluminum workpiece can enhance significantly. Improvement of up to 40% for drill circularity and a reduction of up to 37% in thrust force were achieved.