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Manufacturing

Rapid Prototyping Gets Real

21 Jan, 2007 By: Kenneth Wong

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RP becomes RM -- rapid manufacturing, that is -- as companies use functional prototypes to get products to market faster.

A prototype by its definition is a tangible example of an idea -- the physical incarnation of a product concept, not the end product itself. It's not supposed to be boxed and shipped to the customer. But several years ago, a camera parts supplier began doing just that. It relied on RedEye RPM, the rapid prototyping and manufactured parts division at Stratasys, to create nearly 2,000 units of a plastic camera enclosure destined for field use. That's when RedEye RPM realized it had entered a new market: rapid manufacturing.

The Birth of RedEye RPM
Stratasys' core business revolves around developing and selling RP systems. Its machines employ FDM (fused deposition modeling) -- a method of building parts by extruding semi-molten plastic through a heated nozzle -- in conjunction with 3D CAD data.

"Stratasys did not have a large service bureau presence -- that was intentional," says Jeff Hanson, sales manager for RedEye RPM (rapid prototype and manufactured parts). "We didn't anticipate the need because our systems were designed for end use." Nor did Stratasys want to compete with its own customers, many of whom use the machines to operate RP service bureaus.

However, to win business, Stratasys' sales representatives would routinely offer one or two sample prototypes free of charge. "Soon our reps were bringing in more than one or two [prototype requests], so we started charging for them," Hanson explains. Then the revenue stream from this side business became too significant for the company accountants to ignore. "So we added more machines to accommodate the overflow businesses from our [RP service bureau] customers." Eventually, the part-making business division of Stratasys became RedEye RPM.

By the time RP industry consultant Terry Wohlers of Wohlers Associates visited Stratasys's office in Eden Prairie, Minnesota, there were no less than 60 machines churning out a variety of parts. They included plastic housings for hand-held medical devices for heart patients and flashlight-mounting instruments destined for the U.S. Army's M16s. ("Sixty Machines at Work," August 3, 2006, Wohlers Associates).

Functional Prototype
"When the photography industry migrated from film to digital, [our customer] needed to modify some of their camera enclosures, so they started using our services just to validate their design before tooling," Hanson recalls.

To accommodate the ever-changing shape of popular camera models, the customer returned the following year for a redesigned enclosure. "The complexity of the geometry increased the price and the delivery time for tooling," Hanson says. Furthermore, the new version included an inconvenient draft angle that the customer's tooling facility couldn't easily execute, he explains.

The FDM machine, on the other hand, was able to generate the desired shape without difficulty. So the customer placed an initial order for 500 units with RedEye RPM to move forward with the production process while it waited for tooling issues to be resolved.

"We banged those 500 out very quickly," Hanson says. "[With tooling], it would take as long as six weeks for the machinery setup. We were giving them parts [in increments] five days later." Due to outcomes from various rounds of beta testing, the design was modified seven times before it was finalized. Whereas the RP machine could simply replace the old CAD file with the new one to accommodate such changes, the tooler would have had a hard time altering the semi-permanent machine setup in the same scenario, Hanson points out.

The FDM parts were produced in PC/ABS (polycarbonate/acrylonitrile-butadiene-styrene), the same material used in injection molding. "So they have the same static discharge, emission and EFI (electronic frequency interference) properties," Hanson explains.

If the prototype behaves and operates like the end product itself, is it still a prototype? As far as the consumer is concerned, there may be little difference between the former and the later.

What Can You Make with RPM?
"Our parts can be a bridge to keep production going while you wait for tooling setup," Hanson says. "We're not saying we're better or cheaper than injection molding, but you can use [RPM] in conjunction with molding. In low volume production runs, you can use it in lieu of molding."

Commenting on the parts RedEye has been producing, Wohlers observes, "Volumes are relatively low, so the production of tooling is an expensive proposition. All of the parts are relatively small and surface finish is not critical. As a result, it is feasible to produce these parts much faster and less expensively with additive processes, compared to the alternative of making molds and using injection molding."

Hanson will be the first to admit that rapid manufacturing is bound to cost more than traditional manufacturing methods in single unit price comparisons, but he reminds us that the speed and the luxury of modifying your design can overcome the traditional costs required to modify tooling; therefore, the total ROI (return on investment) of the project, he points out, may show cost savings using the FDM technology as a rapid-manufacturing process. He wants you also to consider another variable that's not so easy to quantify: "Your product is being shipped while you wait for tooling. When the goal is to get to market faster, this is crucial."

Wohlers summarizes, "When considering the cost of using additive fabrication versus conventional methods, such as injection molding, one must consider the production volume. If the volume is low, an additive process may be far less expensive. If the production run is high, it can be far more expensive. So, it is important to determine the break-even point by estimating the tooling and molding costs and comparing them to 'growing' the parts using FDM or another additive process."