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Development of new PM materials and processes during the last decade has led to an increased use of PM components in automotive applications. To maintain its competitiveness towards other manufacturing techniques, the PM industry must continue to combine high demands on mechanical properties with maintained or even improved close tolerances of the sintered components in a robust, reliable and cost effective way. As the PM technology offers a wide selection of alloys that can be processed under a variety of conditions it is of outmost importance to know the influence of each on the both performance and robustness of the PM part to secure a reliable function in the final application. In this paper the influence of material and processing conditions on dimensional tolerances and reliability are discussed. A case study is presented describing results from manufacturing of belt pulleys in a state-of-the-art hydraulic press.

In-situ formed Al-AlN sintered composite materials have been developed by the direct nitriding process based on the reaction of the aluminum matrix to nitrogen gas during sintering. A traditional press-sinter(P/S) method, hot extrusion(H/E) and powder forging (P/F) processes are available to consolidate the composite aluminum alloys. Fine AlN particles less than 1 μm in diameter dispersed as hard particles in the material have a significantly strong bonding to the matrix. They have an important role to improve wear resistance equivalent to the hard anodizing or Ni-P plating. The aluminum alloy also shows a low friction coefficient (less than 0.01) under oil lubricating conditions because fine AlN particles make it possible to form oil film at the interface between the counterpart material.

A new sintered composite friction material consisting of mechanically-alloyed copper-based composite powders has been developed. It has a unique microstructure of fine hard particles that are embedded in the matrix of the copper-based primary particles. This friction material reduces abrasive wear and/or seizures that are often caused by hard particles which become detached from the matrix, because the hard particles in this material are bonded tightly to the matrix even under harsh service conditions. The fine hard particles are also very useful for improving high friction force when contacting a surface material. Therefore, this new friction material provides a higher friction coefficient than the conventional material containing coarse hard particles. Furthermore, this friction material is less abrasive to the surface material than the conventional one.

An internal gear-type pump has advantages compared with an external involute gear-type pump, for example, higher mechanical or volumetric efficiency, considerable reduction of weight and dimension in the oil-pump system[1]. This paper presents characteristics of the internal gear type rotors with a modified trochoidal profile in the oil-pump system, and new P/M(Powder Metallurgy) aluminum alloys which satisfy required wear properties as the lubrication oil-pump rotors. Also, the advantage of high volumetric efficiency and discharge performance and excellent properties of the oil-pump rotor with a modified trochoid profile were combined with a R/S (Rapidly Solidified) aluminum alloy in the scavenging pump for racing car engine. Good results without wear or damage after an actual race are also reported.

We have developed new P/M Al-Si wrought alloys having high strength and high wear resistance for use in the rotors and vanes of rotary car air conditioners. In addition, combined with the development of near-net-shape extrusion technologies, through a joint project with Diesel Kiki Co.,Ltd., we have succeeded in the world's first mass production of rotors made of P/M aluminum wrought alloy. In this paper, the properties and production technology of vanes and rotors made with new P/M Al-Si wrought alloys are presented.

A sintered steel with a high rolling contact fatigue strength of 1660 MPa was developed using a new process and modified powder. It is expected to be used for heavy duty gears and races for automatic transmissions. The process consists of compacting, sintering, repressing and a deep carburization. It is a more simple process than the conventional one like hot powder forging and the repress-resintering process. The repressing is used to get a density of 7.4 g/cm3 and above. Another of its merit is a better dimensional tolerance and economic efficiency. Deep carburization is used to obtain a very hard surface layer and good mechanical properties by means of resintering pores upset by repressing. Some process parameters and chemical composition are to be discussed in terms of the rolling contact fatigue strength compared to wrought steels.

The sensor ring for Antilock Brake Systems was developed by the Powder metallurgy(P/M) process. The P/M process provides the following merits;better dimensional tolerance, flexibility of tooth design, versatility of the materials, and better economics. Residual porosity introduced by the P/M process decreases the output voltage of the sensor. A representative porosity of 10% was confirmed to be allowable. By developing a new surface treatment suited to P/M parts which contain the residual porosity, we succeeded in developing the P/M sensor ring which can endure a 500 Hr. salt spray test.