SPH Simulation of the Embossing and Injection Moulding of Micro-Parts: Softening and Aggregation Aspects

D. Kauzlarić(a), L. Pastewka(b), C. Bretthauer(a), A. Greiner(a), J. G. Korvink(a)
a: Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany
b: Fraunhofer Institute for Mechanics of Materials, Freiburg, Germany

Abstract

We present an approach based on Smoothed Particle Hydrodynamics (SPH) for the predictive simulation of ultrasonic embossing and injection moulding of micro-components. The material is represented by a set of moving fluid particles, carrying all relevant physical information. In order to discretise arbitrary transport equations, the idea of interpolation over the discrete particle data is used. We use this approach for the non-isothermal modelling of embossing of polymers and for the injection moulding of feedstocks with suspended powder particles (powder injection moulding, PIM). For the former we incorporate softening by introducing a temperature dependent yield-stress model based on viscosity regularisation. For the simulation of powder filled feedstocks, we perform an SPH-discretisation of a continuum model for particle migration. For both models, simulation results are presented for engineering relevant mould geometries. The embossing simulations show a softening below the glass transition temperature. The simulation of powder injection moulding shows an aggregation of the solid particles, eventually leading to failures during sintering.