The design-for-manufacturability concept has been around for a while, but now technology is facilitating early-stage simulated manufacturing.

DESIGNERS NOW STAND AT the threshold of a next-generation paradigm that begins with the cre-ation of all components of a product in three-dimensional vir-tual space. But new tools also simulate the manufacturing process itself, allowing problems to emerge before the design ever leaves the engineering workstation. This new paradigm started with computer-aided design and computer-aided manufacturing, but has the po-tential to advance much further. First-generation CAD/CAM technology simply took the drawing board, straight edge, and prototype and replaced pen-cil with keyboard and mouse, paper with CRT display, and prototype with two-dimensional simulation. "What is occurring in engineering de-sign is a breakdown in the compartmen-talization of the process," says Dave Weisberg, president of Technology Au-tomation Services. "Design engineers used to develop a design concept and pass it on to detailers," who would pro duce the drawings. Then still another department would analyze the design and determine its manufacturability. Manufacturability is a key design issue at Apple Computer Inc., Palo Alto, Calif., and the process requires far less paper than in the past. "Once we have been given a brief from mar-keting," says industrial designer Daniele De Iuliis, "we'll sketch, we'll use paper, we'll make mockups." The Apple design team also will use blocks that represent the various drives and other physical components of the prod-uct under development. However, from that point on, says De Iuliis, "there is very little paper in-volved. The sketches will become 2-D CAD drawings. We have our own CAD facility, and we'll turn the 2-D drawings into 3-D models. With our own CNC machine, a five-axis mill, we can ma-chine directly from these 3-D CAD files and very quickly have a true represen-tation of the design. These are the same files we will send to engineers, which they will use to create the actual parts." That allows Apple designers to retain "total control of the surface we created in the design studio." The whole process of design for manufacturing should be reconsid-ered, believes Marc Halpern, director of research for engineering, manufac-turing, and design at D.H. Brown As-sociates, Port Chester, N.Y. For one thing, "the vehicle of communication should not be a drawing. If you are go-ing to create drawings at all, it should not be a downstream process after the design is completed. Any drawings should be done by the designer." Although "there is lots of room for im-provement in terms of adopting technol-ogy," Halpern contends that manufac-turers "are going to have to modify their processes significantly to make the technology work. What we have seen in the aerospace and automotive areas is that if you adopt these technologies without changing design and product-development processes, the technology can actually cause an increase in time to market rather than a decrease. "Manufacturing and design people need to be well-coordinated. Designers must know what kind of manufacturing information has to be specified and doc-umented on a 3-D computer model and what kind of tooling is available so the part can be constructed with 3-D fea-tures that are compatible with manu-facturing capability. When you change design, it can have huge ramifications for manufacturing process plans. It's well understood how to do that with drawings, but not with 3-D technology." Several tools that didn't exist until recently could facilitate the transition, says CAD/CAM analyst Ray Kurland. For example, he cites stereolithogra-phy, which allows a 3-D plastic model of a part to be built in 10 to 12 hours directly from a computer model. Stereolithography "allows you to grow parts overnight," says Apple's De Iuliis. That can eliminate the need to machine parts in creating prototypes, and that can save valuable time. ANOTHER VALUABLE TECHnique, says Kurland, "is verification and simulation. If your part is meant to be molded, cast, or die-stamped, NC machine programming with verification and simulation on the computer can point out potential design flaws [that will affect the ma-chining] process. Before you even cut metal, you can simulate [the process] and verify exactly how the machine tool will actually do it." That kind of technology can head off a lot of manufacturing problems long before production. Parts can and have been designed that cannot be ma-chined with available equipment. If a plant has only a three-axis mill that can't angle the tool, the designer must take that limitation into consideration. Kurland attributes slow progress in this area to a common design-engineer mind-set that essentially says, "My job is to design the best product. It's the other guy's job is to figure out how to manufacture it." But that's gradually changing as the demands of the mar-ket change. "What is really driving progress," explains Kurland, "is the time-to-market concept. [Manufactur-ers] need to overlap the front half of the manufacturing process with the back end of the design process so that you can start setting up for manufac-turing [as early as possible] in the de-sign process. We need to give design engineers a better understanding of the manufacturing processes and what [exists] downstream in terms of manufacturing, tools, fixtures, jigs." Even with currently available hard-ware and software, Weisberg argues, design engineers can do a significant level of analysis on their own designs. For producing typical run-of-the mill parts, engineers can take the design process from original concept right up to simulations that can evaluate the manufacturability of the component. That's far more important than it may sound. "In the past, simple parts were not analyzed either for strength or manufacturability, and it was the simplest parts that tended to be the ones that failed," Weisberg points out. "Now it's a much easier job for the en-gineers to run all of the parts through analysis." That can slash the time needed for product design and devel-opment by 50% or more. Of even more significance will be the impact on the role technology plays in manufacturing companies. "What we have done with computers for the past 50 years," Weisberg says, "is try to em-ulate what we did before we had com-puters. In design situations, that was producing 2-D design drawings. Now we're starting to come up with new cre-ative ideas on how to structure a com-pany around the technology."

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