Direct Laser Sintering of Ceramics

Abstract

For more than one decade layer manufacturing technologies assist the development of new products. Due to a layer-wise build-up of a three-dimensional geometry, nearly every complex design is producible in a short period of time. Selective Laser Sintering is a powderbased technique to produce plastic prototypes (Rapid Prototyping) or metal mould inserts (Rapid Tooling). The laser sintering of ceramic powder is not yet commercialized but applications could be both Rapid Prototyping and Rapid Tooling. The former involves the laser sintering of investment casting shells and cores to cast metal prototypes and the latter the laser sintering of ceramic master patterns for metal spray forming of steel mould inserts. The advantage compared to actual processes are a faster availability of the final product. To facilitate these applications, special ceramic powders as well as new process parameter combinations were investigated. This paper will present achieved results within the abovedescribed applications. Introduction Steadily decreasing product life cycles make it ever more important to reduce the development time for new products. Time-to-market instead of development costs has become the key factor for a products success. New methods from the organizational (Simultaneous Engineering) and the operative point of view have been developed [1]. At the end of a product development, technical prototypes which closely resemble the final product are demanded. Viable solutions for plastic components have been around for years, but the prototyping of metal components has often thought to be too time-consuming, and has been unable to meet comparable specifications. The fast production of metal prototypes still remains a central concern in the area of layer manufacturing technologies [2]. Within the sphere of direct manufacture of metal prototypes, a few technologies such as 3D Printing or laser sintering are already commercialized. Since laser sintered or 3D printed metal prototypes contain low melting alloys, the mechanical properties are limited. The indirect manufacture of metal prototypes provides two different approaches either the direct Rapid Tooling where mould inserts instead of prototypes are layer-manufactured or the combination of Rapid Prototyping techniques and casting processes (indirect Rapid Tooling). The direct Rapid Tooling is utilized if higher quantities of prototypes are necessary. To date, this application achieves good results for plastic injection molding. Examinations and case studies of Magnesium and Aluminum die casting or thixo casting are carried out at several research institutes [2, 3, 4].