Study of Compaction and Ejection Properties of Powder Mixes Processed by Warm Compaction

Warm compaction takes advantage of temperature to favor densification during compaction. However, this technique requires powder mixes with specific physical characteristics to be adequately processed in the temperature range involved in warm pressing. The mix formulation, especially the lubricant/binder system, should provide good flowability and compressibility and lubrication of the die walls to ensure high green densities and low ejection forces. The behavior of powder mixes made with different lubricants processed by warm compaction was investigated with an instrumented compacting device to quantify the phenomena taking place during the compaction and ejection processes. In particular, the influence of compacting temperature and part height on the level of friction at the die walls, the intrinsic compactability, volume expansion and, the ejection stripping and sliding pressures are discussed.