As incremental sheet forming (ISF) is a relatively new micro-forming process, only a few FE models are available in literature to study its process mechanics. The objective of this article is to develop an efficient FE model for ISF so that the unknown stress state, excessive thinning and part failure can be successfully predicted for any process parameters, materials and part geometry.

Material behavior varies significantly when a metal forming process is scaled down to the micro/meso-scale due to higher grain size to sheet thickness ratio. It also results in the reduced limiting drawing ratio due to irregular strain distribution.

Therefore, an FE model is developed to improve the process performance of µISF. A conical part with 45° wall angle is designed and formed on a 50 µm thin AL 1100 foil. Four different models are developed to study the effect of solid vs. shell element-type,  different mass scaling (M. S.) and stiffness-based hourglass (HG) control technique.

An FE model for ISF is developed and experimentally validated for a truncated cone 45° geometry. Some of the key findings from this study are -  

• Simulation with M. S. = 1x10^7 resulted in wrinkles on the part geometry and sudden jump in predicted force values due to high oscillations in kinetic energy. However, reducing it to 1x10^6 yielded most optimum results with force prediction error below 10%.

• Implementing stiffness-based hourglass control helped reduce the computation time by 25% compared to that of M. S. = 1x10^7 but provides inferior force prediction with error above 20%.