State-of-the-art review on ultrasonic vibration-assisted micro-drilling

The increasing demand for accuracy and miniaturization has greatly highlighted the significance of micro-drilling, and it has become a prominent micromachining technique. The capacity to accurately drill holes in various materials has brought about significant improvements across several industries, facilitating them to achieve new levels of productivity and effectiveness, such as in aerospace, automobiles, medical, and microelectronics. However, due to the growing demands of these industries, conventional micro-drilling (CMD) is no longer sufficient to achieve precision accuracy. Therefore, to meet the requirements, researchers have proposed ultrasonic vibration-assisted micro-drilling (UVAMD), a versatile, cost-effective, and efficient technique based on the CMD. It is a novel technique to achieve enhanced machining accuracy by applying high-frequency, low-amplitude vibrations directed toward the tool or workpiece in the feed direction. The use of vibrations enhances chip breaking, hence reducing burr formation, thrust forces, and rubbing between the tool and chip, resulting in superior surface finish quality of the micro-hole, especially for difficult-to-cut materials. This review article evaluates cutting tools and workpiece materials, along with the effects of UVAMD on chip morphology, burr formation, tool wear, cutting forces, and surface integrity. Additionally, it summarizes the ultrasonic vibration devices used for micro-drilling and the sustainability aspects of ultrasonic vibration machining.