Rapid prototyping report

By: 
September 28, 1998

Rapid Prototyping & Manufacturing '97, held in Dearborn, MI, offered attendees a bird's-eye view of advances and trends within this rapidly growing field. Sponsored by the Rapid Prototyping Assn. of SME, the conference and exhibition reflected an estimated 43 percent industry growth in the past year. For those who couldn't attend, IMM offers the following capsulated version of developments and predictions of interest to designers, molders, and moldmakers.

  • Terry Wohlers, president of Wohlers Assoc. (Fort Collins, CO), has been following the RP industry for a decade as an independent consultant and keeps a keen eye on burgeoning trends and technologies. In the executive summary that opened the RP&M conference, Wohlers listed several key observations-an industry emphasis on rapid tooling, growth in the use of 3-D printers and concept modelers, service bureaus now offering a broad range of services, and lower-cost solid modelers, the software needed for creating rapid prototypes.
  • The exhibitors at this year's conference ranged from stereolithography manufacturers and software suppliers to custom molders specializing in aluminum prototype tooling.
  • Stephen Deak, manager of RP services for Hasbro Toy Group, presented his views on using the right material for prototypes. At the Cincinnati facility, for example, designers can choose from ABS, PS, PP, acetal, and others based on the material that will be used in the final product. Most SLS and SLA equipment is limited in the type of materials available, so Deak recommends aluminum tooling or direct injection onto SL tools. For example, on a Star Wars vehicle missile, Hasbro spent only one day building the SL tool, and a second day molding prototypes on it.
  • Laser engineered net shaping (LENS) is a system developed at Sandia National Laboratories under the direction of Michelle Griffith. To produce metal cores and cavities, designers begin with an STL file, then translate it to the LENS device. Metal powders ranging from nickel alloys to stainless and tool steels are delivered from a nozzle to an area on which a focused laser beam cures them. Unlike other PM technologies, the end result is a fully dense metal part with no porosity in the microstructure. All that is required to begin production molding, says Griffith, is one finish pass.
  • Jeffrey Heath of Xerox Corp. explained that the secret to faster time to market lies in SL tooling for low cost, quick, high-quality moldings: "Using molding machines and SLA equipment, we're able to mold prototypes in the material of choice, then send them out for customer feedback before we commit to a new design."
  • On the subject of designing parts for SL tools, Todd Ray, vice president of technology for Compression Inc., recommended the following based on a comparative study: run long cycle times, use SLS composite nylon to create molds for high-heat materials, use SLA for the greatest detail but maintain low temperatures, factor in more polishing time for SLS molds, and refrain from trying to mold parts with deep thin ribs, which can cause processing difficulties.
  • Robert Connelly, a project engineer for Becton Dickinson, offered two case studies showing how precise medical components can be successfully molded in production quantities using the 3D-Keltool process.

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