Experimental investigation and numerical simulation in micro wire-drawing

With the aim of developing numerical and tribological models suitable to be applied in bulk micro-forming processes, the authors propose to focus the research on a specific plastic deformation process: the drawing of micro wires. This process has been chosen because it can be considered a quasi-stationary process where tribological conditions at the interface between the material and the die can be assumed to be constant during the whole deformation. Two different materials have been investigated: i) a low-carbon steel and, ii) a nonferrous metal (copper). The tensile tests performed on each drawn wire show, specially for low-carbon steel wires, a thin hardened layer (more evident than in macro wires) on the external surface of the wire. The experimental investigation performed on fine wires has been numerically simulated using the FE code MSC.Superform. For the copper wire traditional material constitutive model seems to be adequate to predict experimentation. For the lowcarbon steel a modified constitutive material model has been proposed and implemented in the FE code in order to fit the experimental results. The results indicate that the modified model of the process shows a better agreement with the experiments.