Technical Paper: PIM International, Vol.2 No. 4 December 2008, pages 60-63, 1264 words

Authors: Kazuaki Nishiyabu [1] Ian Andrews [1] and Shigeo Tanaka [2]

[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

Abstract

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 (ì-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 ì-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.

Introduction

A gearwheel is a component within a transmission device that transmits rotational force to another gear or device and is also a machine element for high-accuracy positioning. In recent years some advanced micro-manufacturing processes and the micro-sized gears made of metals and some advanced ceramics were demonstrated [1]. Furthermore, micro-planetary gear motors made of Ni-Fe and Ni-based bulk metallic glasses were developed by X-ray lithography & electro-deposition (direct-LIG) method [2] and injection moulding method [3], respectively.

However, micro-sized gears made of general-purpose durable materials are demanded for miniaturisation and reliability improvement of products, and also manufacturing is aiming to achieve a high economical efficiency for industrial needs. Micro metal powder injection moulding (ì-MIM) process is useful for producing the micro-sized and micro-structured parts [4-5]. However, the accuracy of micro-gears manufactured by ì-MIM process has not been clarified sufficiently because of the difficulty of measuring.......

Further sections of this article include:

- Experimental Procedure
- Results and Discussion
- Conclusion
- Acknowledgment
- References

Figures and Tables:

Fig. 1 Micro-planetary-gear manufactured by MIM process
Fig. 2 Four shape deviations and principle definition of gear teeth
Fig. 3 Diameters of addendum circle (da) and root circle (df)
Fig. 4 Tooth thicknesss (s)
Fig. 5 Total runout (Fr)
Fig. 6 Single pitch deviation (fpt) and accumulated pitch deviation (Fp)
Fig. 7 Tooth profile deviation (Fá)
Fig. 8 Microstructures of ultra-compact gears

Table 1 Specification of planet gear (as sintered)
Table 2 Specification of planet gear calculated by considering the shrinkage
Table 3 Accuracy classes for four shape deviations in MIM process
Table 4 Vickers hardness and relative density