Metal Powder Injection Molding Computer Simulation

In this paper, the finite element analysis software ANSYS/CFX is successfully applied to simulate the filling process of Metal Injection Molding (MIM). On some desiderated problems of the filling process of MIM, what we have done is a series of fundamental studies and numerical simulation analysis.On the basis of analyzing the mechanics of MIM feedstock filling process, assuming that feedstock melt is homogeneous and incompressible non-Newtonian, whose flow type is laminar flow. Combining the hydrodynamic and thermodynamics theory, powder particles are supposed to be pseudo-fluid by Euler method, also recognized that the powder particles and the binder are mutually infiltrate continuous fluid. Then the mass equation, momentum equation and energy equation were deduced, and the mathematical model of powder-binder two phase flow for MIM was established. For the rheological character of MIM feedstock melt, the synthesis rheological equation is the best choice to describe the filling process, which have been fit and amendment with viscosity data. The mathematical description of flowing boundariy condition and diathermanous initial value condition was been discussion, and the front of the flowing melt is traced by VOF method.The algorithm and flow process chart had been studied, and the rheological equation of the MIM feedstock was added to the viscous models of ANSYS/CFX by second-developed, which was complied with CEL language and the system was reintegrated. This was the first time to apply the two phase flow mathematical medel to the filling process of MIM successfully by ANSYS/CFX. Take the test sample for example, the process of MIM feedstock filling sample cavity was simulated, and the simulation results were analyzed with the CFX-Post, mainly studied on the effects of the inlets position, injection temperature, injection velocity, injection pressure and predicted the conditions for some defects which often appeard in the filling process of the MIM. After adjusted the technological paramer, the simulation results were consistent with the experiment results in performance, and which certificated the feasibility and accuracy of 3D simulation on MIM filling process.