SIGNIFICANCE OF RAPID PROTOTYPING

Introducing new products at ever increasing rates is crucial for remaining successful in a competitive global economy; decreasing product development cycle times and increasing product complexity require new ways to realize innovative ideas. In response to these challenges, industry and academia have invented a spectrum of technologies that help to develop new products and to broaden the number of product alternatives. Examples of these technologies include feature-based design, design for manufacturability analysis, simulation, computational prototyping, and virtual and physical prototyping. Most designers agree that "getting physical fast" is critical in exploring novel design concepts. The sooner designers experiment with new products, the faster they gain inspiration for further design changes. During the last decade a new physical rapid prototyping concept called layered manufacturing or solid freeform fabrication (SFF) has gained popularity worldwide. The key idea of this new rapid prototyping technology is based on decomposition of 3-D computer models into thin cross-sectional layers, followed by physically forming the layers and stacking them up "layer by layer." Creating 3D objects in a layered fashion is an idea almost as old as human civilization. Constructions as early as the Egyptian pyramids were likely built block by block, layer by layer. Stacking up layers of individually shaped material layers also has a long tradition in a range of manufacturing applications such as tape casting and shape melting.

A little more than a decade ago, the art of building 3D objects by layers was significantly advanced by 3D Systems Inc., a U.S. company based in southern California. Availability of 3D computer models was crucial to realizing the concept of layered object creation, but other technologies such as affordable laser systems, photocurable materials, and powerful personal computers helped to disseminate this technology, called stereolithography. This technology today is capable of producing highly complex 3D geometries with little or no human intervention. Emerging almost in parallel with the advancement of stereolithography were alternative systems for layered manufacturing, offered by a variety of U.S. companies. Included are systems that build layered objects by lamination of sheet materials (Helisys) and by layered fusion or binding of powder articles (DTM, Soligen) or extruded wires (Stratasys). These processes have added a range of new materials that go beyond those of photocurable polymers as used in stereolithography.

Today the key benefits of layered manufacturing are mostly derived from its ability to rapidly create physical models regardless of shape complexity. Also, models built with the help of layered manufacturing processes are valuable during the process of establishing tools for casting and molding.

To further advance U.S. capability in SFF technology, the U.S. government and industry have initiated a range of research projects. The main goal of these efforts is to manufacture "functional components" rather than the "touch and feel" parts that the majority of today's SFF technologies produce. Following the U.S. lead, Europe and Japan have also identified layered manufacturing as a key technology. A number of programs have been initiated in this area. For example, Germany's Fraunhofer Gesellschaft, a nonprofit research organization with more than forty laboratories supported by government and industry, has taken the lead in establishing centers for rapid prototyping research nationwide. Results to date show that innovation and coordination have led to successful transfer of SFF technology into European industries. Similarly, the coordination efforts of Japan's Ministry of International Trade and Industry (MITI) have inspired numerous research and development programs in Japan's industrial laboratories and more recently also in university research settings. [An overview of RP technology and usage based on a study trip to Japan by Marshall Burns can be found in his recent report (Burns 1996).]

In Europe and Japan, educational infrastructure and computational environment have been recognized as key factors for broadening the use of RP in industry. Japan has launched a research and development program called CALS (Commerce at Light Speed) with funding exceeding $300 million in 1996 in order to significantly improve the design and manufacturing infrastructure along a broad range of dimensions, with particular emphasis on computational tools in design and manufacturing. This program is expected to grow during the next few years.

While the United States is still leading the world in most aspects of rapid prototyping, Europe and Japan are catching up fast. Technical innovations in the next few years are likely to dominate this field for more than a decade. The combination of government programs and industrial entrepreneurship will determine who will lead this field in the future.

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Published: March 1997; WTEC Hyper-Librarian