High velocity compaction compared with conventional compaction

Abstract

Compaction to full density is a means to deliver performance and precision without the distortion associated with sintering densification. High strain rate compaction using shock waves has been demonstrated as one means to attain full density in the green state. In the present study, variations in the compaction pressure are used to determine the conditions for attaining full density and these conditions are compared between high velocity and traditional die compaction technologies. A diminishing effect of compaction pressure on densification was observed. At the same compaction pressure the green density and hardness were lower using high velocity compaction. Sound velocity measurements in the powder show high velocity compaction did not generate a shock wave. Therefore, under subcritical compaction velocity conditions there is a higher green density from conventional compaction when compared using the same peak pressure.

Comparative research on high-velocity compaction and conventional rigid die compaction

“…These average gains are below earlier reported 0.3 g/cm 3 when iron powders were used to conduct the comparison. In a former research conducted by Sethi et al [12], high-velocity compaction yielded lower density under the same peak pressure when atomized iron powder was impacted. Thereby, as for soft metal powders, loading speed is not the only decisive factor over the green density, while some intrinsic characteristics of the powders cannot be neglected.…”

Experimental studies and modelling of high-velocity loaded iron-powder compacts

“…Kenolube is a lubricant from the same supplier. The theoretical pore-free density of this mix is 7.52 g/cm 3 . The behaviour in the compression state of powder mixes (green strength) was characterised by static and dynamic tests.…”

“…4 has an impact velocity of 13.2 m/s, corresponding to impact energy of 2.7 kJ and a peak force of 776 kN with a maximum compaction pressure of 1581 MPa. The resultant density for this test is 7.4 g/cm 3 . The maximum overall strain rate is of the order 10 2 s −1 for the compactions performed.…”

“…A number of investigations into the HVC process have been published in recent years. All publications indicate that high-density components can be obtained using HVC [1][2][3][4][5][6]. Other characteristics are low spring back, low ejection forces and uniform densities.…”

The effect of impact compaction on surface quality of powder discs

“…A number of investigations of the HVC process have been published recently. All publications indicate that high-density components can be obtained using HVC [2][3][4][5][6][7]. Other characteristics are low spring back, low ejection forces and uniform densities.…”