Design and Validation of Elastic Dies for Enhanced Metal Powder Compaction: A FEM and Experimental Study.

Abstract

Metal powder compaction in rigid dies often suffers from high ejection forces, non-uniform density, and accelerated tool wear. We investigate an elastic-sleeve die concept in which a conical shrink-fit sleeve provides controllable radial confinement during pressing and elastic relaxation during extraction. An extensive experimental program on Fe-based and 316L powders, carried out in parallel with finite element analyses (SolidWorks Simulation version 2021; Marc Mentat 2005), quantified the roles of taper angle (α = 1-4°), axial pretension (Δh = 0.5-1.5 mm), and friction. Contact pressure increased from ≈52 MPa at α = 1° to ≈200 MPa at α = 3°, with negligible gains beyond 3°. For 316L, relative density reached ρ ≈ 0.889 at 325 kN with Δh = 1.5 mm; Fe-Cu-C achieved ρ ≈ 0.865 under identical conditions. The experimental results provided direct validation of the FEM, with calibrated viscoplastic simulations reproducing density-force trends within ≈±5% (mean density error ≈ 4.6%), while mid-stroke force differences (≈15-20%) reflected rearrangement/friction effects not captured by the constitutive law. The combined evidence identifies an optimal window of α ≈ 3° and Δh ≈ 1.0-1.5 mm that maximizes contact pressure and densification without overstressing the sleeve. Elastic relaxation of the sleeve facilitates extraction and suggests reduced ejection effort compared with rigid dies. These findings support elastic dies as a practical route to improved densification and tool life in powder metallurgy.