Finite element analysis (FEA) of metal microforming processes may require Crystal Plasticity Finite Element (CPFE) formulations to incorporate material inhomogeneity as feature size approaches grain size. Presently, it is unknown if the micropunching process, where holes are formed by shearing thin metal foils with a thickness on the same scale as grain size, can be accurately simulated by using the material’s bulk material properties or if CPFE is required. In the current research, validity of conventional FEA in simulating micropunching is investigated as CPFE formulations have yet to be integrated with most commercially available programs. Using DEFORM finite element software, strain hardening and strain rate hardening material models were employed to approximate flow stress when punching 200 μm diameter holes in 25 μm thick annealed copper foil. For validation of peak punching force, micro holes were fabricated with a nominal diameter of 200 μm for die clearances ranging from 7.6% to 48% of material thickness. The average grain size of the foil was determined to be approximately 47 μm. Therefore, micropunching was predominantly through a single grain across foil thickness and less than a grain in the direction of radial die clearance. Results indicate that the homogeneous material model in DEFORM is capable of predicting the maximum punching forces with reasonable accuracy, concluding that a CPFE model is not necessary for this category of micropunching. Regardless of die clearance, the maximum punching force was approximately 3 N.

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