THE IRON-POWDER PROCESS - FROM SCRAP TO NET SHAPE PRECISION COMPONENTS

Ferrous powder metallurgy deals with the mass production of net shape precision components without machining and virtually without scrap los s. The technology has been greatly improved since its inception in the early 1930s. The rate of innovation is still high, and up to this tim e, important technical breakthroughs keep coming along. Most important ly, great improvements in iron powder purity and compressiblity have m ade it possible to make parts with high density. The density level has been further increased by the introduction of warm compaction and, ve ry recently, by pressing without the addition of lubricant to the powd er in automatically lubricated dies. Alloy systems capable of bringing materials up to an ultimate tensile strength of >1000 N/mm(2), whilst maintaining tight dimensional tolerances have been developed. New hig hly sophisticated, numerically controlled, press systems are now provi ded, that enables the PM part producer to make complex shapes with hig h reliability and excellent quality. Going from simple space filling a pplications, ferrous PM is now a viable process for making materials w ith high static and dynamic properties, good for the most demanding ap plications in the automotive field. The most difficult of them all, th e transmission gears, will probably become a viable PM product in the 21st century. Another area which holds great promises for the future i s that of soft magnetic PM materials, consisting of individually insul ated iron powder particles. The eddy current losses of such new materi als are cut down substantially in all directions, not just in one as w ith sheet laminates. It is believed that this new technique will find many applications in electrical machines and transformers for low to m edium frequencies. (C) Munksgaard, 1998.