Quantitative modeling and characterization of the size effects in microscale coining process of copper

This paper investigated size effects of copper in microscale coining process. By comparing experimental results with finite element analysis (FEA), the type and contribution of size effects could be identified. We found that the deformation size effect is the most pronounced in microscale coining where grains must be introduced into relatively small die cavities through severe plastic deformation. The magnitude of the deformation size effect was determined by the relative ratio of the grain size to the die cavity, and smaller size factor produced greater effect. We also found that feature height in microscale coining was related to grain size and flow stress of the material. Therefore, size effects could be quantitatively modeled and compensated by calculating equivalent grain size and flow stress correction. After compensating for size effects, the FEA model could accurately predict material forming performance.