IMM Focus: Automotive:RP: Assembly ops proved, standardized in six weeks

Making rapid prototypes involves more than just speed in the fast-paced automotive market.

Design-to-production timelines look like hyphens at automotive tiers these days. Specs are squeaky tight, parts must go into assembly without a hitch, and by the way, costs are locked down. No doubt about it, being an auto supplier takes skill, speed, and nerves of steel. So, when Tier One supplier Visteon got the go-ahead to make taillight assemblies for the Mercury Mountaineer SUV, it was ready to move fast.

The lamp assembly, excluding electrical parts, consists of three molded parts: a housing, a lens, and a grille that enhances the image of ruggedness. Craig Russell, a design engineer at Visteon, says, “We needed to be sure that the separate components would properly fit together and that the assembly [with electrical parts] would fit correctly in the vehicle. We also needed to ensure that not only was the desired appearance achieved, but that the required illumination levels were reached.”

Getting prototypes quickly to test and review the lamp assemblies was critical. Visteon went to Urgent Plastic Services (UPS) of Rochester Hills, MI. Apart from its overall skill at making high-quality rapid prototypes (RPs) for auto applications, UPS had recently added the capability to make light lenses with production-quality reflex characteristics. UPS is also very serious about the R part of RP. Company sources say its combination of technologies, materials, and creative thinking means prototypes are finished 50% to 70% faster than is possible with traditional prototype methods.

Russell says Visteon needed prototypes fast to start testing. UPS responded, completing prototypes in six weeks, which was well within Visteon’s margin. And, Russell adds, UPS engineers recommended several design modifications that resulted in improved assembly of the final product.

A Productive Process

The UPS prototype system, almost all of which is in-house, began with an engineering review of the customer’s design. It was at this stage that UPS recommended to Visteon modifying the channel for the adhesive that attaches the lens and housing, as well as how the grille is attached. Both ideas were accepted. UPS’s next step was to send the design file to one of its stereolithography (SLA) systems to make a model that would serve to check fits and other physical details, plus allow an aesthetic review by designers and stylists.

When the model was approved, UPS’s well-equipped moldmaking operation went to work. The molds for the taillamp were machined from aluminum alloy, which Steve Kelly, UPS senior sales engineer, says saves time but still allows production of thousands of parts with full accuracy. Machining rates alone can save weeks compared with tool steel.

When the three lamp components’ molds were complete, the UPS in-house molding operation took over. Equipped with nine presses ranging from 75 to 1500 tons, it selected a 750-ton system for these molds. The grille was molded in Geloy ASA, which GE Plastics calls the most weatherable polymer in its arsenal. The housing is made of a multisourced PC/ABS blend. The lenses are molded in polycarbonate (Lexan from GE Plastics), even though the original spec was acrylic. Equipped with prototypes early, Visteon’s testing showed that PC would better resist the heat generated by the lamp bulbs.

UPS outsourced the chrome-plating of the inside of the housing for reflectivity and the grille components for a luxury appearance. When the plating was done, the three parts moved into UPS’s assembly operation, along with electrical components supplied by Visteon. From adhesive application to setup time and ease of clip engagement, every option was tested. In the end, clear parameters for efficient assembly were established and documented, and Visteon was ready to go.

Kelly is adamant that the UPS brand of RP is about more than just producing parts. “It consists of the process, the materials, the manufacturability, the costs, the tool designs,” he says. RP should not only conquer time restraints, he adds, but also eliminate the questions and the unexpected—the potential variables that can hamper or halt production.