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2 | Design for Powder Metal Processing INTRODUCTION A variety of structural parts bearings gears and so on are produced from raw materials in the form of powders. This area of processing is generally called powder metallurgy although parts can also be made from nonmetallic powders such as ceramics by these methods. In the main processing sequence used raw material powders are mixed and then compressed into the required shape. The compact is then heated in a controlled atmosphere sintered to bond the particles together and produce the required properties of the part. The powder metallurgy process has a number of features that are not found in other metalworking processes including LI 4J 1. Precise control of material and product properties. Through careful control of the constituent powder materials compaction levels and so on precise control of the final product properties can achieved. 2. Unique material compositions. Although most powder metallurgy parts are produced with standard material compositions 5 6 a wide range of compositions can be produced by the powder metallurgy process including combinations impossible by other means. For example metals and ceramics can be combined by compaction and sintering. 3. Unusual physical properties. Physical properties can be readily varied by powder metallurgy from low-density highly porous filters to high-density parts with low porosity. Tensile strengths can also be varied from low to very high. It is possible to compact dissimilar materials in layers to obtain different properties at various places in the part. The porosity can be 461 Marcel Dekker Inc. 270 Madison Avenue New York New York 10016 462 Chapter 11 Process Type FIG. Material utilization for basic shape-producing processes. Adapted from Ref. 7. controlled so that impregnation with oil or other lubricants can lead to selflubricating properties for bearings. 4. Net-shape manufacturing. Complex-shaped parts that require no further processing can be .

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