Site: Fraunhofer Institut Für Produktiontechnologie (IPT)
Steinbachstrasse 17
D-52074 Aachen, Germany

Date Visited: 17 October 1995

JTEC/WTEC Attendees: R. Brown (report author), J. Beaman, B. Kramer

Hosts:

Stefan Nöken, Dipl. Ing., Process Technologies Department
Ivo Celi, Dipl. Ing., Process Technologies Department

BACKGROUND

(See the ICT site report for a brief general introduction to the Fraunhofer Institutes and the Fraunhofer Rapid Prototyping Network.)

The Fraunhofer Institut für Produktiontechnologie (IPT) was established in 1980 in proximity to the RWTH Technical Institute of Aachen and located next to the WZL (Machine Tool Institute). The four professors of WZL are also in charge of the four major departments of IPT:

The activities of the RP program are cross-functional to all IPT departments. Unlike most of the other Fraunhofer Institutes, the 62 members of IPT's professional staff are expected to remain there for only five years while they obtain their Dr.-Ing. degrees. This staff is supported by 176 students and 38 nontechnical assistants and technicians. Sources of revenue are 45% industrial contract, 25% base funding, and 30% public funding (the EC and the German government).

IPT operates a large open bay machine tool laboratory and is constructing 1,500 square meters of additional laboratory space to increase the size of its laboratory by 50%. Equipment and software within the RP group include the following:

CAD             CATIA
                EUCLID (FIDES)
                ProEngineer
RP Machines     EOS STEREOS 600 (stereolithography)
                EOSINT P 350 (laser sintering)
                EOSCAN 100 (digitizer)
                Experimental SLS
                Experimental Laser Generation Process

RP was started as a new initiative at IPT in 1992. IPT led the coordination of the seven Fraunhofer Institutes involved in RP. The IPT RP group's mission includes the following functions:

The group operates the commercial RP equipment in its laboratory primarily to fulfill its role of introducing RP processes and capabilities to industry. It does not compete with service bureaus.

RESEARCH AND DEVELOPMENT ACTIVITIES

IPT engineers have developed two experimental RP machines. One machine is an experimental SLS-type unit designed for direct metal sintering. It is equipped with a 300 W Nd:YAG laser that normally operates in the 200 W range. The beam is moved with a scanner mirror system from above the work chamber to provide a ~100 mm diameter work area that can be shrouded with a protective gas. The system is not designed to hold an atmosphere in the work chamber. This unit is used for direct sintering of uncoated powder metals, including bronze (Electrolux material) aluminum, copper, and 316L stainless steel. With this unit researchers have achieved up to 90% theoretical density. In addition, they have experimented with ceramics.

The second experimental system, laser-generated RP, is designed to melt metal powder as it drops from a coaxial laser/distribution cone. Other concentric cones within the probe deliver shroud gas and fluids for cooling. Researchers use either a 900 W CO2 laser or a 1,000 W Nd:YAG laser. Full-density parts are claimed to be produced with this unit. Within the work chamber is a 2_-D milling cutter to finish the walls of the metal part and improve tolerances. The Laser-Generated RP unit was to be shown at the EUROMOLD Exhibition in Frankfurt, Germany, in December 1995. The IPT hosts showed us both thin-wall and solid parts made of steel from this experimental unit. IPT plans to commercially develop this system with a die casting machine tool company over the next several years. With significant funding from the commercial partner, the chances of commercializing this technique appear promising.

GENERAL DISCUSSIONS

IPT representatives indicated that RP is not as popular in Germany as it is in the United States, for several reasons:

When asked what German companies would like improved in RP, the team's hosts indicated the following:

Overall, IPT staff feel that RP will not displace all applications of rapid prototyping using conventional techniques. Conventional machining processes have made rapid strides in the past five years and will continue to do so. RP will find its place among competing techniques, but will not displace all other construction techniques.

SUMMARY

IPT staff have extensive knowledge and capabilities in tooling, conventional laser and ultrasonic machining, and advanced grinding techniques. They are developing knowledge and experience in RP, and have great potential to develop new RP processes that overcome many of the current limitations.


Published: September 1996; WTEC Hyper-Librarian