An Inverse Technique for Evaluation of Flow Parameters of Modeling Materials Using Extrusion


K.K. Pathak, Advanced Materials and Processes Research Institute (CSIR), Bhopal, MP 462026, India


Modeling materials such as plasticine are used for studying the hot deformation processes as their property can be easily correlated with hot metal. Being soft in nature, they take very less energy in forming as compared to real material. Hence flow behavior, surface roughness, and possible defects can be easily visualized using experimentation with modeling materials. However, being soft in nature, it is quite difficult to evaluate their flow properties. Neither tension nor compression test can be successfully attempted. To accurately determine the flow parameters, an inverse engineering technique which is based on elaborate analytical studies of rod extrusion process has been proposed. Using Sachs's analytical model and varying the material parameters, extrusion loads are evaluated for large number of conditions. Friction is also considered as variable. Material modeling is carried out using rate power law. Using these data, a contour map is generated to predict material and friction parameters for real experimental extrusion load. The proposed contour map is successfully validated for two plasticine experiments and found to be quite accurate. The proposed contour map offers a powerful tool to characterize modeling material using extrusion process which is otherwise not possible using conventional tension or compression tests.