MAKING THE TRANSITION TO 3D SOLIDS

3D solid modeling is a relatively new concept to design and manufacturing -- less than 30 years old. Its widespread use in practice is even more recent, made possible by the large increases of the past 15 years in the information processing power-to-cost ratio. On the other hand, engineering drawing using paper and pencil has evolved over 150 years. Although designers have migrated to solid modeling because analysis is more easily handled, manufacturing engineers by and large still rely on drawings. The reason is more complex than that it requires a pro forma change in the way engineers view parts. An engineering drawing is a sophisticated language for building things and contains many nongeometric elements like tolerances, notes, and procedures that are meaningful to production. A solid model is simply a geometric representation of shape.

It is therefore not surprising to find manufacturing-oriented companies, both large and small, changing only slowly to 3D solid modeling. The JTEC/WTEC panel found this to be particularly true in Japan, where use of 3D solids was estimated to be between 3% and 20%. Whatever the actual percentages, it is apparent that a sizable number of RP users in Japan are not utilizing 3D solids at present. On the other hand, solid modeling for RP is used widely in Europe, but still not as extensively as in the United States, where the solid model is seen as a key element in the next-generation design and manufacturing data representation that will supersede drawings, because it will be able to support automated processes.

The reason for the perceived slow adoption of 3D solids in Japan is not entirely clear. One answer may be that the panel did not see a suitable cross-section of activity in large user companies because their RP technology was employed in the development of new proprietary products. Another reason may be that SFF is still too embryonic and relatively imprecise to attract serious attention across a large segment of Japanese industry. The current benefits of RP technology are perhaps perceived to be too small when compared with the fast turnaround and high quality achieved by Japanese NC (numeric control) machining technology, which is the best in the world. NC parts are produced directly from 2D drawings today.

Rapid prototyping will come into its own when the industry goes beyond making parts faster and starts producing parts not possible by any other means. Sachs et al. (1995) give a relevant example dealing with the creation of cooling channels that conform to the shape of the injection molding tooling, as opposed to the traditionally machined straight channels. The conformal channels give precise temperature control of the molding cavity throughout the process cycle and reduce the part production cycle time.

It is a significant problem in Japan that most 2D part drawings must be recreated with 3D data before proceeding with RP, since much of this work is done manually.

Table 8.1 lists comments concerning this issue that the JTEC/WTEC panel collected from various Japanese hosts, primarily at the service bureaus. When the JTEC/WTEC team mentioned such comments to MITI representatives, the response was that they recognize that this is a problem and they would like to see change, but there are no programs specifically aimed at accelerating the acceptance of 3D solid modeling. Several hosts noted, however, that this and other RP topics may be addressed within the large supplementary budget programs recently enacted by the Japanese government, with the most likely candidate being a major CALS (Commerce at Light Speed) program dealing with information integration in manufacturing.

Table 8.1
1995 Company Estimates of 3D Solid Modeling Use in Japan

The panel's hosts also predicted dramatic changes in the future. They relate that Japanese industry has realized the strategic value of 3D solids; at the time of the JTEC/WTEC visit to Japan, plans were already in place to transition to 3D CAD, with large companies expected to begin the shift within two years.

Few comments surfaced from the European site visits that expressed concern about the issue of 2D drawing versus 3D solid modeling. Instead, the issues in Europe seem to be related to cost and ease of use.

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Published: March 1997; WTEC Hyper-Librarian