Progress in the simulation of microPIM
Professor Jan Korvink and his research team at the Laboratory for Simulation, University of Freiburg, Germany, have been developing simulation technology for micro Powder Injection Moulding of both ceramics and metals using Smoothed Particle Hydrodynamics (SPH) in order to meet the computational challenge for complex, strongly deformed materials.
The researchers state that feedstocks for microPIM possess a significant yield stress which can be modelled by means of the viscosity regularisation technique, the approximation of the yielded and unyielded domains of the material by two different viscosities. Incorporated into the particle based SPH-formalism, the model successfully reproduces an experimental observation of splitting in a channel with cylindrical obstacle.
Shear induced powder migration was incorporated by means of the diffusive flux model developed by R. J. Phillips, et al (Phys. Fluids A, 4(1):30-40, 1992). This model was discretised by formulating an SPH-equation of motion for the occupied volume of the solids fraction with exact conservation properties. The simulations correctly predicted powder migration to regions with the lowest shear rates. For Powder Injection Moulding into complex geometries the simulations help to predict an accumulation of the solids fraction at convex corners (pointing outside of the cavity) and a depletion at concave corners (pointing inside the cavity).
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