Quantitative study of powder binder separation of feedstocks
Martin Jenni (1), Lukas Schimmer (1), Rudolf Zauner (2), Juergen Stampfl (3) and Jeff Morris (4)

(1) Austrian Research Centers GmbH – ARC, A-2444 Seibersdorf, Austria
(2) Verbund – Austrian Renewable Power GmbH, A-1010 Wien, Austria
(3) Vienna University of Technology, Institute of Materials Science and Technology, A-1040 Vienna, Austria
(4) City College of New York, Levich Institute & Chemical Engineering, NY 10031 New York, USA

The rheological properties of feedstocks and their flowability and tendency for powder binder separation have a strong influence on the successful manufacturing of PIM components. A systematic comparison of the filling behaviour of different tungsten and aluminium feedstocks has been carried out experimentally. Using specially designed moulds, designed experiments (DOE) with variations in the nozzle temperature, mould temperature an injection speed of feedstocks with extremely different physical and thermal properties (tungsten and aluminium) were carried out. The results were statistically analysed. The observed effects are explained and implications for optimised PIM processing are suggested. Furthermore parts of the samples are analysed for powder separation and compared to predictions made by the pseudo-continuum separations model named: Balance Model.
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The effect of the carbon content on microstructure and tensile properties of a MIM 17-4PH stainless steels has been investigated.  Carbon content influences the formation of delta ferrite at high temperature, which increases sintered density. However, delta ferrite causes a decrease of tensile strength, without a corresponding increase in ductility. In the presence of large amounts of delta ferrite, ductility decreases significantly.
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Accuracy evaluation of ultra-compact gears manufactured by the microMIM process
Kazuaki Nishiyabu1a Ian Andrews1b and Shigeo Tanaka2c

1 Osaka Prefectural College of Technology, 26-12 Saiwai, Neyagawa, Osaka 572-8572
2 Taisei Kogyo Co., Ltd., 26-1 Ikeda-kita, Neyagawa, Osaka 572-0073, JAPAN

The production of micro-size and micro-structured parts by metal powder injection moulding (MIM) process require more sophisticated techniques than conventional MIM. New techniques for the quality evaluation of those tiny parts are also necessary to be developed. A micro-planetary gear made of 17-4PH stainless steel has been developed by micro metal powder injection moulding (μ-MIM) process. This study describes the method of fabrication and quality evaluation of the ultra-compact planet gears (module: m=0.07, number of teeth: z=24) manufactured by μ-MIM. Cross-sections of the gear teeth were observed with a digital microscope and dimensions of the teeth were measured by image analysis. The variation in dimensions of teeth was evaluated for mould, green compacts, sintered parts and age-hardened ones. It was shown that those experiments contributed useful information on the quality of the ultra-compact gears.
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