Efficient electromagnetic micropunching technology for producing well-ordered, high-density micropits

Micropits are favorable for interfacial lubrication and cell culturing. This study developed an AC electromagnetic-driven high-speed micropunching mechanism capable of rapidly fabricating a large-numbered array of well-ordered micropits. The designed mechanism converts 60-Hz AC into 120-Hz electromagnetic force, which in turn drives a punching-shaft to complete a high-speed punching movement at 120-Hz. The micropunching mechanism is installed on a desktop gantry framework to create a stable, high-speed CNC micropunching system. Combining an eddy current sensor with an oscilloscope determines optimal spring stiffness for the system. A micropunching experiment is performed using a micropunching tool comprised of electrically conductive polycrystalline composite diamond (ECPCD) and an annealed aluminum alloy workpiece. The results revealed that a 120-Hz punching-frequency, a spring stiffness of 2.7 N/mm, and a workpiece moving speed of 2160 mm/min generate micropits with a high-integrity profile. It takes only 3.4 seconds to complete 400 high-integrity, well-organized micropits, with a depth of 23.0–23.3 μm that are burr-free and almost chipless, indicating the proposed high-speed electromagnetic micropunching technology is highly precise and efficient while also being energy-saving.