Feature article: PIM International, Vol.3 No. 2 June 2009, pages 21-29, 4013 words

Author: Professor Randall M. German, San Diego State University, USA

Associate Dean of Engineering, College of Engineering, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-1326, USA

In the light of an increasing global demand for microPIM (µPIM) components, leaders in the field came together at a special workshop held as part of the PIM2009 Conference, Lake Buena Vista, Orlando, USA between 4-6 March 2009.

In this specially commissioned report for Powder Injection Moulding International, Professor Randall German looks at the key issues that were identified, including both the technical and commercial challenges that lie ahead.

Introduction

The production of microminiature components is a rapidly growing area, with much early success using plastic and silicon materials. In recent years the production of microminiature devices has expanded from lithography, machining and plastic moulding to include powder injection moulding techniques.

Over the past five years these activities have accelerated as smaller powders have become available in a few different materials, especially those compatible with medical applications. Simultaneously, designers in various fields have begun to specify microminiature powder injection moulding for a variety of components, for use in automotive systems, computers, jewellery, eyeglasses, fibre optic systems, lasers, opto-electronic systems, nozzles, dental instruments, acceleration sensors, electronic assembly tools, data storage devices, communication systems, and surgical tools. This activity is expected to accelerate.

In the meantime, the information on microminiature powder injection moulding (µPIM) is poorly organised. There are no newsletters, conferences, journals, or any semblance of topical organisation for the field, similar to how powder injection moulding was in the late 1980s.

In March 2009 a group of experts on diverse fields such as biomaterials, biology, dentistry, lithography, physics, and powder injection moulding met in Lake Buena Vista, Florida, USA, to discuss the status of the field, and to identify the research needs and opportunities evident for microminiature injection moulding for medical and dental applications.

This Workshop took place immediately following the PIM 2009 Conference and Tutorial organised by the Metal Powder Industries Federation. The workshop overview below gives some details on the event. Table 1 lists the speakers on microminiature powder injection moulding, giving those that spoke at the PIM Conference and also those that spoke at the Workshop. Obviously there is much activity in the field and the range of presentation topics shows the focus of the research and development efforts.

Author

Professor German is the author of 850 articles, 15 books, and 23 patents and has been active in PIM for over 20 years. He conducts research and consults with firms on issues of customer development, technology enhancements, new product development, and R&D policy. He founded and co-chaired the annual PIM Symposium. He has written three books on PIM.

Further sections of this article include:

- Background
- Status of µPIM
- Technology report
- Identified needs and priorities
- Summary
- Acknowledgements
- References

Figures and Tables:

Fig. 1 An example PIM stainless laparoscopic surgery component, with a 29.5g mass, 20mm diameter base and overall length of 45mm (Component courtesy MimEcrisa)

Fig. 2 Microdevice stainless steel surgical biopsy cutter fabricated with less than 100micrometer wall thickness and length of 6mm (Component courtesy Boston Scientific)

Fig. 3 Microfeatured 35mm long dental endodontic device. Shown moulded (left) and sintered (right) with a close up on the micrometer sized features, reflecting the current state of microminiature powder injection moulding and one example discussed in the Workshop (Photographs courtesy Young Sam Kwon)

Fig. 4 Various views of stainless steel orthodontic brackets as examples of high production quantity µPIM components. The scale at the bottom shows 1mm steps

Fig. 5 A cellular telephone component fabricated using µPIM to provide a 2000 MPa tensile strength (Photograph courtesy Kuen-Shyang Hwang)

Fig. 6 Stainless steel micropillar arrays as representations of microfeatured devices produced via µPIM. The left image is as-moulded and the right image is as-sintered (Photographs courtesy Ngiap Hiang Loh)

Fig. 7 Demonstration of microminiature zirconia gear and gear wheel produced via µPIM shown at the tip of a pencil (Photograph courtesy Volker Piotter)

Fig. 8 Micrograph of the Parides sesostris butterfly scales. The gross arrangement of scales shows a brilliant green colour, but as shown in Fig. 9 this is due to Bragg’s scattering on nanoscale features (Photograph courtesy Giselle Thibaudeau)

Fig. 9 High magnification scanning electron micrograph of the same butterfly scales as shown in

Fig. 8. At the higher magnification the nanostructure becomes visible leading to the structural colour via Bragg’s scattering (Photograph courtesy Giselle Thibaudeau)

Fig. 10 An early demonstration of a two material combination in µPIM where miniature alumina and zirconia components are joined [Photograph courtesy of Volker Piotter]

Fig. 11 The near-full dense microstructure from an agglomerated nanoscale powder after injection moulding and sintering at 1000°C (Photograph courtesy Jai-Sung Lee)

Fig. 12 The application of computer simulation in support of µPIM, in this case to examine the mixing of feedstock using a static mixer (Image courtesy Seokyoung Ahn)

Fig. 13 Four glimpses of the atomic motion occurring during the sintering of nanoscale tungsten particles, showing an almost fluid phase at the particle surface (Images courtesy S. J. Park and S. G. Kim)

Table 1 Speakers at the MicroPIM Workshop, plus MicroPIM related speakers from the PIM2009 Conference

Table 2 Current status and key needs for MicroPIM