New Segregation-Free Iron-Based Powder Mixture Effective for Reducing Ejection Force during Ejection Process after Compaction

A new segregation-free iron-based powder mixture with excellent lubricity was developed. The most notable feature of this new powder mixture is superior lubricity compared with mixtures containing conventional lubricants such as zinc stearate. In addition, clean sintered surfaces can be obtained because the new mixture does not contain zinc stearate. These features will contribute to improvement of product quality and the yield rate of sintered parts. The mechanism of the excellent lubricity of this powder mixture was investigated by SEM/EDX analysis of green compact surfaces. The analysis indicated that the ejection force of the compacts made of this powder mixture was reduced by concentration of the lubricant between the compact and the die wall surface during the compaction process.