ADVANCES IN INSULATED POWDER TECHNOLOGY

The powder metallurgy technique is a well established process for the cost effective production of near net shape products in long series. S oft magnetic materials utilise the premix and compacting techniques of powder metallurgy. High purity powder particles with high compressabi lity are required to ensure good soft magnetic properties. Improvement s in the compressability of the powder combined with advances in compa cting techniques such as warm compacting result in high density compon ents suitable for commercial production. High induction in powder base d products is dependant on the density. In order to ensure low eddy cu rrent loss at medium frequency a continuous insulation layer between p articles is applied. The thickness of the insulation layer should be m inimised in order to maintain the compressibility of the powder and re sultant induction. The insulation layer should remain intact after com pacting at high pressure. Additives are a normal requirement in the ma ss production of powder components as lubrication for easy removal of the component from the tool is required. In the case of insulated powd er particles where the thin insulation layer must be maintained, addit ives may also be used to increase the strength. In the case of convent ional irregular particle Corm, the magnetic and thermal properties whi ch can be achieved are isotropic. This permits the design of motors wi th three dimensional flux and limits the constraints imposed by anisot ropic materials.