Surface quality improvements of WC–Co micro-punch finished by ion beam irradiation for micro-punching process of metal foil

Non-contact surface finishing processes have become an important issue in fabricating micro-die for micro-forming technology. In the paper, surface finishing processes of WC–Co flat sample and micro-punch having ultrafine grains were carried out by ion beam irradiation with Ar ion beam. The surface roughness Ra value of micro-punch was decreased from submicron to nano-scale and the profile accuracy was improved significantly compared with the original sample fabricated by micro-grinding. Moreover, the ultrafine grain microstructure can still be intact after ion beam bombardment with irradiation time of 240 min. Micro-punching tests of metal foil were conducted with ion beam finished micro-punch and micro-holes of 400 μm and 600 μm in diameters were punched with good dimensional accuracy. The surface roughness of cross-section of micro-inner-hole was decreased from 0.22 μm to 40 nm. Therefore, surface finishing process by ion beam irradiation can effectively improve surface quality of micro-die for micro-punching with no apparent damage due to the non-contact polishing.