When Sun Microsystems Inc. in Mountain View, CA, set out to plan its Enterprise 10000 server -- popularly known as the "Starfire," it took an unusual approach for the high-end computer market: It accorded the exterior of the product as much care and concern as the inside engine.

"When you're asking people to pay $870,000 and up for a product, you want them to say 'wow' when they first see it," said Kathleen McLaurin, a buyer/planner with Sun. "By going with a thermoformed plastic enclosure panel designed by Donald C. Goss and manufactured by Laguna Niguel, CA-based Furon Co., we achieved a dynamic, even dramatic exterior look that achieved the 'wow' factor we were seeking. We have no doubt that it has contributed to the Starfire server's excellent reception in the marketplace," McLaurin added.

Launched in early 1997, the Starfire server has enjoyed a great deal of success. Heralded as one of the most important product introductions in Sun's history, it is a powerful single system server and -- the company claims -- is the first to rival the mainframe in functionality. Accommodating up to 64 processors as well as 20+ TB of disk storage, this new data center server offers up to four times the performance at half the cost of mainframe and other competitive servers, McLaurin said.

"We knew we had a great-performing system to offer, but we also wanted it to look like a million dollars. It was especially important that the product appeal visually to the design-sensitive commercial users we were targeting," said McLaurin. To achieve this goal, the Sun marketing department became involved during the early planning phases of the project and played a major role in determining the design of the exterior enclosure panel. The company also retained consultant and lecturer Donald Goss to spearhead the design and balance styling with production concerns.

Design & Forming Parameters
Since the removable enclosure panel was to be functional and cosmetic, Goss initially presented several design approaches for Sun's review. The selected design was a dynamic panel treatment featuring smooth curves, contoured louvers and a stylish two-tone paint system consisting of a charcoal gray background with Sun blue accent stripes in the louvers.

To reduce the perceived physical size of the Starfire server's cabinet, the cosmetic panel had to be 48 inches wide by 66 inches long by 5 inches deep. Yet, despite its size, it had to weigh less than 50 pounds for ease of handling and be strong enough to maintain rigidity when removed. Flatness and squareness tolerances also had to be extremely tight -- ± .050 inch -- to ensure a proper fit.

"To meet these requirements, we knew the part had to be plastic," said Goss. "The relatively low-production volume compared to desktop systems, the sharp detail required, the weight and size requirements and the lower tooling costs all pointed to thermoforming as the best production method."

Sun launched a comprehensive search to find a pressure former capable of forming to the specified tolerances and quantity. Of more than 30 pressure formers initially surveyed by telephone, only nine survived the first cut.

"Don Goss and I hit the road together to visit these companies and review their tooling processes, their quality control procedures and their overall knowledge of thermoforming," McLaurin said. They eventually developed a "short list" of four suppliers before selecting Furon Co. to supply the part.

"Quality is everything to Sun," Goss said. "They wanted consistent quality with no rejects, and they were perceptive enough to understand the difference between price and cost. Furon offered the best Class A tooling, a very effective approach to Early Supplier Involvement (ESI), plus the ability to work with large parts from a material handling standpoint. So it was really the best of all worlds."

Production Challenges
The Furon team, headed by product leader Robert Bogue and assisted by manufacturing engineer Patrick Fox, worked closely with Goss to overcome a variety of design and production challenges. The first was to develop a suitable forming approach. Twin-sheet forming would have produced the most economical parts, but the production volumes anticipated at that time could not justify the much higher tooling costs involved.

"As an alternative, I came up with a 'mock' twin-sheet design using separate inside and outside pieces that are bonded together," Goss said. "The contoured styling worked to our advantage. The outside portion has two large cylindrical sections that provide vertical rigidity, while the internal piece has horizontal corrugations. When you bond the two together, you get an extremely rigid structure," he added.

From Furon's standpoint, one of the most difficult challenges was to meet the extremely tight tolerances required for the panels. "At Furon's Seattle facility, where the panels are manufactured, we always educate our customers on the advantages of temperature-controlled molds. Temperature controlling our molds allows us to consistently make parts without warpage, eliminating stress and unwanted bending or puddling. It also enables us to achieve the very close tolerances required to make these parts," said Furon's Bogue.

For Sun's product, Furon specified both molds to be water-cooled cast aluminum. According to Bogue, the actual length, width, and squareness tolerances have averaged as little as ± .020 inch, exceeding the ± .050-inch specification. Even after a change in material grade, from UL94H-B rated ABS to a UL94V-0 rating, Furon has been able to maintain very close tolerances.

Fabricating the Panels
Furon utilizes two thermoformers to form the panels: a Maac pressure former with a 5-foot by 9-foot platen size and a General Plastics Machine (GPM) pressure and twin sheet former with a 51Ú2-foot by 7-foot platen. After the inner and outer panels are formed, they are trimmed on a five-axis Motionmaster Model SB-55XT CNC router. The router features dual 5-foot by 5-foot tables, which can be used singly or in combination, 30 inches of Z motion and an eight-tool position toolchanger.

The inner panel is machined to locate the hanging hardware, and the outer panel's side walls and center rib are machined to thickness to allow for the inner panel to accurately seat inside during the bonding process.

"The parts, as molded, are actually designed to have an interference, which allows us to mate the machined non-mold surfaces on the outer panel to molded surfaces on the inner panel," Bogue said. "This prevents inconsistencies during assembly which might be caused by variations of the outer panel's non-mold surfaces."

Once the parts are bonded together, the periphery is machined to height, eliminating mismatch between the side walls of the inner and outer panels. In an effort to save on tooling costs and improve quality, Furon designed a fixture which accommodates the initial machining of the outer panel, the bonding process and the final trim.

Application of the two-tone paint system, a critical factor in the appearance of the panel, also proved challenging. The water-based paint specified by Sun is environmentally friendly, but more difficult to apply than traditional solvent-based coatings. "While some paint preparation is necessary, the high quality of the tooling allows us to keep it to a minimum," Bogue said. For the dual-color design, the smooth Sun blue accent stripes are painted first, and then the rest of the panel is painted a lightly textured gray.

"The ability to maintain close-formed and machined tolerances, along with close monitoring of the painting process, have allowed us to be successful," Bogue added.

Award-Winning Results
Due to its success in meeting critical aesthetic, rigidity and weight requirements, Furon recently received an award for the enclosure panel from the Society of Plastics Engineers Thermoforming Division.

The Starfire server itself is also an award winner. The product was selected by Network Magazine as a 1997 Product of the Year and was also named Outstanding Server of the Year by Unix Review, Best New Product by Government Computer News and one of the Hot Products of 1997 by Datacommunications magazine.

"At one point during development of this product, it looked as though we might have to settle for a flat metal enclosure panel," said Sun's McLaurin, "but we all stuck together and worked out the problems. What we ended up with is a terrific looking product. And though it's impossible to measure the sales impact of the enclosure panel, we know it's played an important role in the Starfire server's success."

Patrick Fox is the product engineer for Furon Co. in Seattle, WA.

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