In Europe the use of RP for investment casting is limited but increasing. As the use of CAD solid modeling increases, application of rapid prototyping for manufacturing metal investment castings will also increase. Table 10.2 summarizes some German-manufactured rapid prototyping systems.
Dassault Aviation (France) is a frequent user of RP patterns for investment casting. In the same manner as many U.S. companies, Dassault designs and manufactures complex metal castings using 3D Systems' QuickCast build style to fabricate patterns. Dassault engineers have worked with several foundries to develop process parameters for successfully casting RP patterns. Dassault has certified RP castings for use in testing prototype flight hardware. In addition, some German companies use the expertise of Dassault to get metal castings from RP patterns.
The European automotive industry has also had success using RP castings. Typically, a company sends a CAD solid model of the design to the United States for pattern fabrication, a U.S. foundry does the casting, and the part is delivered back to the company. One such successful case study is documented in the recently published book Stereolithography and other RP&M Technologies (Jacobs 1996). Mercedes-Benz Division of Daimler-Benz designed a new four-cylinder engine block using CATIA solid modeling software. The solid model design of the full-size engine block was sent to 3D Systems Technical Center in Darmstadt, Germany, for pattern fabrication. The completed investment casting pattern was then sent to Solidiform, Inc., in Dallas, Texas, for investment casting. The completed aluminum casting was then sent back to Mercedes-Benz, resulting in a significant savings in time and cost.
Schneider Prototyping, the largest service bureau in Germany, has developed a proprietary process for casting metal parts from the Cubital SGC process. Metal castings account for 15-20% of Schneider's work. Cubital is developing a process for fabricating wax patterns by capturing a wax shape within a thin polymer coating.
The Fraunhofer Institute for Applied Materials Research (IFAM) currently uses the Stratasys FDM process to fabricate wax patterns for investment casting. It is also involved in a demonstration project for investment casting of custom medical implants in a joint effort with a medical clinic, an implant manufacturer, and an investment casting foundry.
Electro Optical Systems (EOS), a manufacturer of rapid prototyping systems, is developing processes and materials focused on metal casting applications.
Cubital is developing a process for fabricating wax patterns for investment casting by capturing the wax shape within a thin polymer coating. The polymer coating is subsequently removed, leaving the wax pattern.
The enabling technology for use of rapid prototyping processes is CAD solid modeling. The CAD solid model captures the geometry, which can be easily processed in any RP machine. The use of CAD solid modeling in Europe is not widespread; however, its use and application are increasing. As the use of solid modeling and rapid prototyping increases, the use of investment RP patterns is increasing as well. European RP manufacturers recognize the potential for metal casting applications and are developing new processes and materials for use in metal casting. In addition, German foundries are learning to cast RP patterns. They have had more success casting polystyrene patterns than stereolithography QuickCast patterns.