Lubricating effect on density distribution in uniaxial powder compaction

Y. Taniguchi*, K. Dohda, Z. Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Density distribution in powder compact caused by frictional force at die wall has been estimated. The iron and pre-alloyed stainless powder were tested. The magnitude of density distribution was characterized as the slope of axial density variation α. The pressure transmission ratio λ (derived as the slope of relation between upper and lower punch during compaction) was obtained to estimate the frictional force on die wall during compaction. Friction coefficient on die wall was also measured, and the behavior of the zinc stearate, StZn (applied as admixed lubricant or die wall lubricant) in uniaxial powder compaction process was estimated. Admixed StZn prevents the occurrence of density distribution and uniform green compact is obtained in the critical amount of lubricant, however, even though the lubricant amount increases λ increases less because the radial stress increases. The die wall lubrication is more effective to increase λ in comparison with the admixed lubrication, but since the ability of StZn is poor a decreases less and uniformity of density is improved little. More effective die wall lubricant will be necessary to obtain the uniform compact without pressure increase and its ability becomes more important in the case of pre-alloyed stainless powder since the higher radial stress is observed.

Original languageEnglish (US)
Pages (from-to)356-362
Number of pages7
JournalMaterials Forum
Volume29
StatePublished - Sep 6 2005

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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