Parameters in a complex material model for powder compaction, based on a continuum mechanics approach, are evaluated using real insert geometries. The parameter sensitivity with respect to density and stress after compaction, pertinent to a wide range of geometries, is studied in order to investigate completeness and limitations of the material model. Finite element simulations with varied material parameters are used to build surrogate models for the sensitivity study. The conclusion from this analysis is that a simplification of the material model is relevant, especially for simple insert geometries. Parameters linked to anisotropy and the plastic strain evolution angle have a small impact on the final result.
The rate-dependence of hardmetal powder pressing in cutting insert production is investigated experimentally and numerically. In the latter case, the finite element method is relied upon using a continuum mechanics approach. In particular, possible rate-dependency due to creep deformation and rate-dependent friction is discussed with the experimental investigation focusing mainly on dimensional changes during sintering but also pressing forces. The results indicate that rate-dependent frictional effects are the dominating feature and accordingly, it can be argued that for the metal powders investigated here, creep deformations do not have to be accounted for in the constitutive description at the timescales relevant for powder pressing and when the shape after sintering is concerned. For the present powder, the apparent frictional effect decreases at higher pressing rates. Additional details of the friction behavior are studied comparing finite element simulations with experiments.
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