Date Visited: 26 October 1995
JTEC/WTEC Attendees: F. Prinz (report author)
The Daimler Benz (DB) automotive division (Mercedes Benz, MB) has 3 laboratories (2 at Untertčrkheim and 1 at Sindelfingen). All labs serve as service centers for MB product development. In particular, they focus on tasks that cannot be done by outside RP service centers on a routine basis. The laboratory in Sindelfingen has one SLA 250 and one C-MET station and is in the process of acquiring a DTM laser sintering station. MB managers consider the automotive industry in Germany to be the leading user community for RP, followed by the appliance industry. They consider that the majority of innovative ideas in RP are still coming out of the United States rather than Europe or Japan.
MB is most interested in epoxy-based resins. MB researchers have reported satisfactory results with Ciba resins with regard to accuracy, distortion, and mechanical properties. The JTEC/WTEC team's hosts noted that ABS-like materials would be very desirable. They also noted that to the best of their knowledge, no one in Europe was then capable of building functional metal parts or functional metal tooling directly with RP processing. Based on the experience of MB researchers, the quality of RP parts comes at the expense of the time spent to make them. They envision that better times could be achieved if a better recoating system were available.
MB researchers routinely achieve 200 µm RMS accuracy in the XY directions, 250 µm in the Z direction. An accuracy of 70 µm RMS would be satisfactory for their needs. MB focuses R&D efforts on the process, not on the post process.
MB researchers have spent significant efforts to help develop CAD support tools for error-free STL model generation. SYRKO, the DB in-house CAD tool, is fully compatible with the STL or CLI format. (STL is preferred at DB.)
DB is one of the leaders in Europe with respect to research in reverse engineering. Programs are underway to automatically acquire outside and inside surface shapes. At the time of the JTEC/WTEC visit, the DB research focused on geometry only. Future efforts might include material data as well.
MB participates in a range of educational activities to promote the use of RP inside and outside of MB. Many outside activities are done in coordination with VDI (the equivalent of Japan's small and medium-sized enterprises group, SME). NC Gesellschaft is considered another key promoter for RP technology in Germany.
MB is in an RP development partnership with BMW, Rover, Fiat, EOS, and Deskarts. This group receives funding from the EU under the BRITE EuRAM umbrella to develop RP methods for making parts directly from the "technical material," which means material for the target application, such as tool steel. Total funding is ECU 2 million (about DM 4 million). The main foci of this development effort are injection molding and deep drawing.
Tooling is considered the most important application area for use of RP technologies.
MB participated in a study where an injection molding tool was fabricated directly from an a 3 mm thick SLA shell, which was later back-filled with a mix of aluminum shots and epoxy resin. This tool lasted for about 200 injection-molded parts.