| Résumé | Good powder mix flowability is required in high-volume powder metallurgy (P/M) manufacturing in order to ensure a uniform and consistent filling of the die cavities and, in turn, high productivity, low rejection rates, part integrity and consistent part-to-part characteristics such as dimensional change. Apart from the particle size and the shape of the metallic powders and additives, lubricants, even though admixed in small quantities (<1.5 weight %), have a significant impact on the flow characteristics of powder lend formulations. In addition to that, the blending parameters and the atmospheric conditions such as powder temperature and atmosphere temperature and humidity, may also affect significantly the flow of powder mixes. For instance, it is know that some mixes produced during humid and hot summer days may behave differently. In this paper, the effect of relative humidity and temperature on the flow of conventional P/M mixes containing different types of lubricants was studied. Typically, amide wax, Kenolube, zinc stearate as well as proprietary lubricants were admixed in a V-blender enclused in an environmental chamber set at different humidity and temperature levels to simulate different atmospheric and processing conditions. The sensitivity to such conditions of the different lubricants was assessed and the influence on the flow of the powder mixes as well as on the compaction and ejection behaviors was measured. |
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