Press Release
LIGHT SPEED…PROTOTYPE TAIL LAMP ASSEMBLIES MADE FAST
Urgent Plastic Services' rapid response and six week completion of injection molding the 2002 Mountaineer's prototype tail lamp components, including grill, housing and lens, helped to assure the vehicle's desired "rugged performance, luxury ride" appearance.
SUV's prototype lighting lens package produced in six weeks, not months, by rapid prototype firm.
First…there was the sport sedan. Now, rugged luxury. Automakers combining two dissimilar images in one vehicle to broaden its appeal is the rage, especially with today's upscale SUVs. Elegant toughness may be all the buzz among the marketing teams, but for the designers and stylists, it's a daunting task to marry the two concepts into one package. The new styles can also be a challenge for the engineers selecting the manufacturing processes, tools and materials that will produce the sturdy-but-comfortable look. One place, however, where there can be no problems encountered is on the assembly line when the two images of ruggedness and luxury are joined at production volumes. That's why the prototype process is a necessary and important step in these vehicles' development stages, and, given today's faster than ever design-to-production times, why rapid prototyping is critical.
That's also why, when Tier 1 auto supplier Visteon was given the go-ahead to manufacture rear tail light assemblies for 2002 model year Mercury Mountaineer SUV, they turned to Urgent Plastic Services (UPS) of Rochester Hills, MI, a specialist in the rapid prototyping of injection molded plastic components. For over three years the company has been working with automakers and suppliers to provide prototype lighting components for new models and concept vehicles including cars, SUVs and trucks…and more recently, has added the ability to create light lenses with actual, production-quality reflex characteristics. The rapid part of the equation means that, in virtually all cases, through the use of advanced technologies, materials, and creative thinking, prototype parts are completed 50 to 70% faster than traditional technologies and prototype manufacturing methods would allow.
"The lamp assembly, not including any electrical parts, consisted of three separate plastic components," relates Craig Russell, Design Engineer at Visteon, "including the housing, lens, and a grill-like overlay that would contribute to the overall appearance of ruggedness. Because of the three parts, 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.
"We had to have prototypes ready quickly in order to test and review the lamp assemblies. UPS's fast response, completing the prototypes in just six weeks, gave us that necessary margin of time. Plus, they (UPS engineers) recommended several design modifications that, when incorporated into the final product, resulted in improved assembly."
Though Mr. Russell was impressed with the turnaround presented by UPS, Steve Kelly, Senior Sales Engineer for UPS puts the SUV tail lamp job in perspective. "In the past, customers had come to expect prototype work for plastic components such as the tail light assemblies to take three, maybe four months or even longer," Kelly reports. "The injection tooling would take most of that time and was expensive, and in many cases the molds would be jury-rigged to produce a few parts. So, the customer might get a prototype that approximated the appearance he was after, but he was not provided any indication of the parts’ true manufacturability or insight into process alternatives and potential complications.
"The rapid prototype process that we've developed eliminates the wasted time of conventional prototype manufacture, but just as important if not more so, is the fact that our parts, tooling and process all approximate production-like conditions, so customers know what to expect and can prepare accordingly."
The rapid prototype process Mr. Kelly refers to consists of multiple stages, virtually all of which are in-house processes at UPS. Today's prototype project typically begins with the customer's submission of parts design, and as was the case in this tail lamp application, a CAD file. At this initial stage, UPS engineers and injection mold process experts review the design, making their recommendations for any changes that could ease manufacturing difficulties or lower costs. For this example, UPS recommended a modification to the channel where adhesive is applied to attach the lens and housing together, and also how the grill would be attached to the housing/lens assembly by means of a snap fit and clips. Both recommendations were accepted and incorporated into the final product design.
After computer designs are approved and any engineering analysis required is completed, UPS may send the design files to one of its stereolithography apparatus (SLA) systems available for producing three-dimensional models of parts, typically completing models in a few hours. SLAs use the CAD data file to generate a dimensional travel path for a laser light source that cures a photosensitive polymer into the size and shape of the part. The resulting model can be used as a "hands-on" reference tool for checking fits, fixturing or machining requirements if needed for subsequent steps, and for aesthetic review by design and stylist experts.
After model approval, the next step in UPS's rapid prototype process is usually building of injection mold dies. Using sophisticated CAM software, CAD data files are once again translated to machining language for use in machining centers, or by high-speed machining and grinding centers for processing carbide tooling for EDM machines, depending upon die characteristics and manufacturing method required. For this SUV light application, the molds were machined from aluminum alloy…like the SLA system, the CAD files generated the path for the machining centers’ cutting tools.
Kelly notes that "the aluminum alloy tooling is another of the time saving steps in the prototype process that we've experimented with and developed over time. The aluminum used is the right combination of machinability that allows us to fabricate dies at fast speeds and feeds yet with durability to mold hundreds of prototypes and even quantities into the thousands of parts without loss of accuracy. The machining rates of the aluminum can save several weeks in the process and still duplicate production-like quality, rates and data."
Once the dies for the three parts were complete, the injection molding process began. Here to, UPS's in-house capabilities played a significant role in the timely completion of the prototypes…with the firm's multiple injection systems ranging from 75 to 1500 ton capacities. For the tail lamp components, shots were done on one of the company's 750 ton models. The grill pieces were molded from GELOY material, the housings were a PC ABS plastic, and the lenses, while an acrylic material was originally specified, were formed in a polycarbonate material. Because of UPS' quick turnaround time in tooling and parts, Visteon was able to advance heat test the lenses and determined that the polycarbonate should be substituted for the acrylic because of its resistance to the heat generated by the lamp bulbs.
With the injection molding shots finished and the three individual parts formed, UPS needed the help of an outside source in completing the tail lamp project. Both the housing and the grill components required a chrome-plate metalized finish…the inside of the housing to provide high reflectivity, and the grill to add a “luxury” chrome appearance.
As the metalizing was completed, UPS's final capabilities were put in motion—assembly of the tail lamps. From adhesive application to setup time, to ease of clip engagement, and with electrical components supplied by Visteon, various options were tried and all of the parameters to efficient assembly were established and documented.
"That's all part of what UPS's rapid prototyping program is about," says Kelly. "It's about more than just producing parts…it consists of the process, the materials, the manufacturability, the costs, tool designs. From the start of the design approval stages, to final assembly, rapid prototyping should not only conquer time restraints but also eliminate the questions and the unexpected, the potential variables that can hamper or halt production."
UPS was established to meet the needs of the plastic parts manufacturing industry, and specializes in the rapid prototyping of injection molded components. It is associated with 3-Dimensional Services and a third company, Urgent Design & Manufacturing…the affiliation provides rapid prototyping of metal components fabricated through machining, stamping, laser processing, and cast and molded in addition to the plastic injection molding process.
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