Short dies and thin walled inserts for room temperature or warm compaction - numerical determination of design features

Abstract

If a certain physical phenomenon is so complex that simplifying hypotheses are inadequate to represent it, the determination of design parameters through analytical procedures is unsuitable. In these cases, a numerical algorithm may be the alternative solution, to simulate the phenomenon in a manner that is more faithful to the actual physical situation. The design parameters of compaction dies have been determined by FEM. To evaluate the effects of higher temperatures, as in warm compaction, the available literature data have been used to include the variations of characteristic parameters of the involved materials. A wide range of die dimensions has been covered, focusing the interest on progressively shorter dies or thin inserts. A die can be coded as short when its axial extension is small in comparison to the radial size, which can vary significantly. Different insert materials have been considered, from HSS to PM steels and Co-WC. The deviations from classical Lame's formulae depend on the geometry of the die elements. The limitation on limit stresses requires a minimum wall thickness of the insert, which is higher than that considered dangerous for the instability of elastic equilibrium.