Study on effect of residual stresses and strains in sequential passes in microwire drawing

Abstract Digital twins (DT) have been widely applied to model complex manufacturing processes and products for various purposes such as implementing controls, monitoring operations, and identifying bottlenecks of manufacturing processes. This paper aims to develop a DT model for a precise wire drawing process with dozens of passes. Metal microwires are required to possess high quality and precision since they are mostly used in micro-electro-mechanical systems (MEMS) in health care. Since microwires are drawn through dozens of passes to reduce their sizes gradually, it is unavoidable that the whole wire-drawing process is affected by numerous factors, and thus might cause defects in production. The developed DT model will help to analyze the effects of main design factors on products, predict the performance of a process, and identify critical ones when a defect occurs. Distinguishing from existing works, this paper emphasizes the effect of existing residual stresses and strains generated in previous passes on these in sequential passes, and it is our finding that only residual strains will be accumulated pass by pass; while the ranges of residual stresses stay at a similar level. This further implies that over-accumulated residual strains, rather than residual stresses, should be emphasized when a defect occurs to a sequential pass.