Advancements in microforming: a key aspect of the present miniaturisation in the production of metallic products

Abstract Microforming is a promising technique for creating miniature metallic parts due to its advantages of high productivity, low cost, near-net-shape capability, and superior mechanical properties compared with other micromanufacturing methods. The rapid miniaturisation of metallic products and devices has intensified research into size effects, deformation mechanisms, and process optimisation at the microscale. Studies reveal that when the specimen-to-grain size ratio ( t/d ) decreases below 2, flow stress can drop by 30%–40%, accompanied by surface roughening and inhomogeneous deformation. In micro deep drawing of stainless steel foils, a maximum limit drawing ratio (LDR) of 2.2 has been achieved, whereas superplastic micro-extrusion of Mg alloys produced defect-free micro-pins and micro-cups with uniform hardness. These findings demonstrate that factors such as grain size, temperature, lubrication, and friction critically influence deformation behaviour. A deeper understanding of these parameters is essential to overcome size-effect-induced challenges and facilitate the reliable industrial application of microforming for medical devices, aerospace components, and MEMS technologies.