Development of micro-nibbling method based on dieless punching

The nibbling process is a method used to cut arbitrary features from thin sheets by continuously piercing partially overlapping holes to form slits. While laser processing is currently the dominant method for such cutting, nibbling offers several advantages, including lower operational costs and the absence of thermal effects on the workpiece. In microfabrication, laser processing has inherent limitations that present both technical and financial challenges. Therefore, this study developed a micro-nibbling method for fabricating microfeatures using a dieless punching technique, where the workpiece is supported from underneath by a backing material, eliminating the need for a die and die set assembly and enabling the practical use of micropunches. A punching device specifically designed for micropunches, fabricated from cemented tungsten carbide using electrical discharge machining, was employed with stainless steel sheets as the workpiece. Initial experiments used a 20 μm-diameter punch on a 5 μm-thick sheet, varying the punch feed pitch from 5 to 15 μm, and successfully produced slits at all pitches, demonstrating the feasibility of the method. Subsequently, punches with diameters below 10 μm were used on 3 μm-thick sheets with feed pitches ranging from 3 to 8 μm. Additionally, slit-and-space patterns were produced using a 5 μm-diameter punch on 2 μm-thick sheets, yielding slits approximately 5 μm wide with comparable spacing. Rotating the punch at 1000 min −1 significantly reduced the punch load compared with non-rotating punches. Finally, the fabrication of cut-out pieces, including a 120 μm square and a 300 μm-radius sector on 5 μm-thick sheets, demonstrated the versatility and applicability of the proposed micro-nibbling method. • The feasibility of micro-nibbling using dieless punching was demonstrated. • Experiments with varied micropunch diameters, feed pitches confirmed slit formation. • Punch rotation, newly introduced in nibbling, effectively reduced the punch load. • Cut-outs, a 120 μm square and a 300 μm sector, showed the method's effectiveness.