High-velocity compaction and conventional compaction of metallic powders; comparison of process parameters and green compact properties

Abstract

High-velocity compaction (HVC) has been used for some years now with commercially available high-energy hydraulic presses. Compact densification is achieved in less than 0.01 s, shorter than with a conventional process (about 1 s) but longer than with explosive compaction (0.001 s). Powders are compacted by means of an adjustable energy instead of force or displacement. This work presents a comparison between conventional compaction (CC) and HVC using an industrial hydraulic press (18 kJ) and a laboratory press (380 J). The velocity of the hammer producing the impact is therefore restricted to 10 m/s. Six powders were compacted using the HVC process and the conventional die compaction process. Differences and similarities are examined considering process characteristics (punch forces, ejection force, and tooling strength) and the characteristics of green compacts (densities, dimensions, and cohesion).