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Investigations into water soluble binder systems for Powder Injection Moulding
Feature article: PIM International, Vol.5 No.1 March 2011, pages 51-54, 1957 words
CRITT-MDTS, 3 Boulevard Jean Delautre, F-08000 Charleville-Mézières, France
Water soluble binder systems for metal and ceramic injection moulding offer several distinct benefits. Compared with thermal debinding, water solvent debinding is regarded as more environmentally friendly, with a faster debinding rate, simpler processing, and a wide range of feedstocks are available.
Delphine Auzène and colleagues from CRITT-MDTS, Charleville-Mézières, France, present a comparative study of some commercially available feedstock systems that can be processed using water solvent debinding.
Introduction
CRITT-MDTS, a centre for innovation and technology transfer specialising in materials, coatings and surface treatment, was founded in 1984 and is an important research and inspection laboratory in France. A team of technicians and engineers offer technical assistance for the characterisation and analysis of materials, as well as the development of new products. In particular, the manufacturing of complex shaped parts by metal and ceramic injection moulding has been studied since 2006.
In 2007 an injection moulding machine, debinding equipment and a sintering furnace was purchased and installed. The mission of CRITT-MDTS is to promote powder injection moulding primarily in the Champagne-Ardennes region of France, but also in Wallonia, Belgium, via the INTERREG IV PRISTIMAT program with SIRRIS and in wider France via collaboration with French PIM networks.
Metal injection moulding has evolved to become a versatile mass production method for a wide range of complex-shaped metal components [1]. The powder is first incorporated into a polymer by high shear mixing at a volume loading typically between 50 and 70 vol %. The melted suspension is injected into a cavity where the polymer solidifies. The task that remains is to remove the organic components before sintering the metal powder assembly. Binder removal is a critical processing step and plays a central role in PIM part production. The main reason for this is that the risk of introducing defects into the components is particularly high during this step [1]. In the past binder removal involved reheating the moulded part to cause thermal, degredative or evaporative loss of the organic phase [2]. This processing step has to be very long in order to avoid sample distortion and defects. Therefore the development of feedstocks for MIM is the area of the technology with the greatest improvement potential. In recent decades considerable progress has been made in feedstock development and binder removal…..….
Further sections of this paper include:
- Experimental details
- Step 1: Injection moulding
- Step 2: Water debinding
- Step 3: Thermal debinding & sintering - Results and discussions
- Binder removal mechanism
- Conclusion
- Authors
- Acknowledgements
- References
Figures and Tables:
Fig. 1 Stéphane Roberjot and Delphine Auzène in the CRITT laboratory
Fig. 2 SEM images of alumina x 8000(a), 316L polyMIM x 1000(b), 316L aquaMIM x 1000(c)
Fig. 3 PolyMIM® 316L SEM binder weight loss according to debinding water curves and corresponding SEM images at 50°C
Fig. 4 AquaMIM® 316L SEM binder weight loss according to debinding water curves and corresponding SEM images at 70°C
Fig. 5 Inmafeed® Al2O3 SEM binder weight loss according to debinding water curves and corresponding SEM images at 50°C
Fig. 6 Schematic illustration of water binder removal (scheme from POLYMIM)
Fig. 7 MIM Parts made of polyMIM Cu999 developed in CRITT-MDTS
Table 1 Characteristics of each feedstock
Table 2 Comparative results for water debinding
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