Technical Paper
The Warm Compaction Process.Basics, Advantages and Limitations
1998-02-23
980334
The origins of the new compacting method are surveyed. The densification enhancement derives from yield strength drop versus temperature and from a most effective lubrication mechanism. For any mix the pore free density figures out the limit density after compaction. The allowances corresponding to volume increase on ejection are evaluated. The curves of porosity versus compaction pressure show that graphite additions can contribute to densification. For part shapes with upper profiles replicating the upper punch faces, the porosity distribution attained by warm compaction is better than that attained by room temperature compaction. The changes with respect to room temperature compaction bring about a higher radial pressure at densification end but a lower residual radial pressure at ejection start. These are the reasons for a relatively high spring-back but low ejection strength.