Development of Powder Lubricant for Compacting Raw Material Powders in Powder Metallurgy

Abstract

This technology was developed by surveying the characteristics of powder lubricants as raw material powders prepared for powder metallurgy from melting and mixing N, N’-ethylene-bis-stearamide (EBS) and lithium stearate. The author found that not only the particle size and composition of the EBS-containing wax composite agent but also the crystal polymorphism that originated from the EBS affected the powder characteristics, lubricant properties, and compact powder characteristics of the metal powder of the raw material and that the difference between the M-type and the S-type presented different trends. The M-type is preferable for the improvement of flow characteristics and the apparent density of the metal powder of the raw material, and the blending quantity of lithium stearate also affects the flow characteristics. The M-type is preferable for the effect of improving transverse rupture strength. The S-type is preferable for the realization of both the reduction of ejection pressure and improvement in the compact powder characteristics (green density and spring back).