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August 26, 1998

4 Min Read
RP accelerates tools for auto parts

Automakers and Tier One molders are operating at a pace akin to that of Germany's Autobahn - no limits. As a result, moldmakers are being asked to rev their engines to the red-line limit. How do manufacturers speed mold production for complex, contoured automotive parts?

At a recent joint conference on rapid tooling for the automotive industry, sponsored by both SAE and RPA/SME, several presenters offered RP-related solutions. Richard Beaudoin, part of GM Powertrain, summed up the current state of RP. "Rapid prototypes and tooling have gone from trinkets and desktop paperweights to functional pieces. Physical models of products and tools help to find design or manufacturing errors without the bulkiness, cost, and time required to obtain the real hardware."

In the past, rapid tools have been limited to relatively small sizes. But recent developments indicate that RP system manufacturers are heading toward larger build areas. Elaine Hunt, a member of Clemson University's Laboratory to Advance Industrial Prototyping, reports that one of the newest RP vendors, Somos Systems, has pushed the envelope on build size with its Aaroflex unit to 22 by 22 by 22 inches. 3D Systems, a leader in the field, introduced its newest SLA-5000 model with a build envelope of 20 by 20 by 23 inches. And the FDM 8000 unit from Stratasys can produce ABS prototypes or tooling patterns up to 18 by 18 by 24 inches.

At United Technologies Automotive in Detroit, rapid prototyping is being used for both direct tooling and composite tooling, according to principal engineer Ed Buzanoski. UT's automobile interiors group uses both SLA and SLS models to create insert mold tooling, and produces composite insert tools from SLA back-filled epoxies. Fillers can include carbides, aluminum, and glass fiber. A high-powered laser and fast-curing epoxy developed for the system increase part detail and boost throughput by 20 percent.

Another success story presented at the conference involved Technimold, a service bureau for RP, rapid tooling, and plastics engineering based in Turin, Italy. Designers at Fiat needed a 400-part production run for a molded component on the Punto Cabriolet. Using an FDM system, Technimold created an ABS prototype, then generated a spray-metal tool directly from it. Fiat received the tool in roughly six weeks, half the time normally required. In addition, it saved about 60 percent of the cost of conventional steel tooling.

Bruce Okkema, vice president of Eagle Design & Technology, an RP service bureau, offers some guidelines for success with rapid tooling projects. "Questions you need to ask yourself include the kind of CAD you have, how much time is available, what material will be used for molding the finished part, what kind of surface finish is required, and how much you can spend." Other suggestions from Okkema: rapid prototyping requires robust CAD models, so make sure your system is up to par; become familiar with tooling options, then establish relationships with tooling sources by doing test parts together before trying production work.

Larger and more precise RP models

Although many predicted that RP parts and tools were merely a passing trend, today's reality is proving them wrong. This is an industry on the move, with 1996 growth rates, of 27 percent. The top three vendors to date, Stratasys, 3D Systems, and Sanders Prototype, have all released new versions in the past year. These recent product introductions point out the goals for RP tooling: tighter tolerances, larger build areas, more speed less expense, and greater ease of use.

Take the newest offereing from 3D Systems, for example. With a layer thickness of .002 inch, preceision improves by 50 percent. The SLA-5000 also boasts an automatic resin refill system, a 40 percent reduction in machine footprint, and an 85 percent reduction in power consumption. For faster build times, it includes a solid-state laser with 25 percent more power than other systems and low-viscosity epoxy designed to cure faster. A recoating system that sweeps only the active area of the part increases productivity up to 20 percent. And the system creates models for direct AIM tools, 3D Keltool, and other tooling options. According to company president, Richard Balanson, 3D has also begun a leasing program to increase affordability of its systems. From Stratasys comes the FDM 8000, with thickness ranges from .002 to .030 inch using ABS modeling material in a variety of colors. Modelmaker II from Sanders features build layers of .0005 inch (.5 mil) using a thermoplastic modeling material in a 12-by-5-by-9-inch envelope.

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