Cubic Finishing of Automotive Interiors

Tim Braniff, director of facilities, Spectrum Industries, Grand Rapids, Michigan, remembers the day in 1992 he received a call from Toyota's engineering staff asking if Spectrum would be interested in finishing the molded wood-grain consoles for the new Avalon planned for production in the U.S. Toyota had been referred to Spectrum by Cubic, the Japanese company that invented the decorative process used by Spectrum.

At the time, Spectrum was well established in high-volume electro-coating for automotive parts, primarily for the engine compartment, but was producing only limited quantities of faux wood-grain consoles and facias for tier-one suppliers to Chrysler. The parts were finished manually using a patented Cubic process for printing wood grain onto injection molded substrates. Then a two-component urethane clear coat for added depth and luster was applied.

Spectrum had been promoting the Cubic process because the end product offered significant advantages over in-mold finishing. Uniform coverage could be achieved with greater precision. The Cubic decoration naturally wrapped the molded part for complete decoration of complex shapes. The Cubic process also produced a smoother, more conforming finish compared to other processes that had limitations on the shape of parts that they could finish. A higher gloss was also obtainable, and the thickness of the two-coat urethane finish added depth. Plus, the pattern of the finish varied slightly from piece to piece providing for a more natural appearance on the part.

Toyota engineers arrived at Spectrum and began working with the company to prepare for the Avalon's 1994 launch. The development team realized that the projected production rates, along with the critical quality requirements set forth by Toyota, required a more sophisticated system than was presently in place. Spectrum officials concluded that an automated process was necessary.

"Toyota put their commitment on the table," said Mr. Braniff, "and we knew we needed to invest in the technology that would make it happen. We needed an automated, clean-room robotic system."

Mr. Braniff began researching finishing system manufacturers and discovered that expertise was hard to find. "Almost all the vendors we contacted claimed they could build robotic systems and clean-rooms, but I knew we were pushing them into unfamiliar territory."

Ironically, the vendor of choice was located only a few miles away. Thierica Equipment Co., Grand Rapids, Michigan, had custom designed and built many different clean-room finishing systems, including a high-volume hard coating system. "Quite frankly, I don't think Thierica took us seriously when I walked them through the section of the plant where we had to shoehorn this new system. We had to literally go through the front wall to make this happen. And, like all production projects, we had a definite time table," stated Mr. Braniff.

The solution took advantage of Spectrum's existing Cubic equipment, adding clean-rooms, robots, ovens and conveyors within a 3,000 sq ft area. The three-story finishing system delivered multi-task performance with the product rates required for Spectrum's growing client base. Molded plastic parts were manually loaded onto an inverted chain-on-edge conveyor and passed through a three-stage wash of acidic cleaner, rinse and deionization to remove impurities and oils. The parts then traveled into a clean-room where they were off-loaded onto a revolving conveyor as part of a three-dimensional printing process.

In the Cubic process, printed film was dispensed from a roll through a rotogravure process where an activating solution was applied to the film, which was then conveyed onto the surface of the warm-water bath. The activating solution reactivated the ink while dissolving the film. Molded plastic parts on a steel rack rotated down through the activated film that transferred the decoration onto the part.

Once the film was applied, the parts were placed on universal fixtures for the topcoat application. Traveling on the conveyor up to the second floor clean-room, the parts moved through a series of wash, dry-off and de-stat stations. The parts then moved into temperature- and humidity-controlled water-wash booths where the high-gloss, two-component urethane finish was sprayed on by two vectored robots. Water-wash booths were used for more efficient capture and removal of overspray. The parts then traveled up through the roof to a large curing oven and back down to ground level where the parts were off-loaded, inspected and packaged. The entire process took two hours.

In addition to locating the curing oven on the roof, an existing exterior wall was knocked down to bring in equipment. Due to the multi-tiered, limited-footprint design, the problems of relatively long-range paint delivery and water recycling also had to be overcome.

Spectrum is a member of an informal, international group of Cubic finishers that meets every three years to exchange information. "One of the special aspects of the Cubic process is that there is a cooperation among the different finishers. That allows an automotive company, such as Ford who is pushing for the globalization of its world standard, to blend different parts into cars produced in any country. We might produce an instrument panel that's put into a car made in Italy with U.K. door trim."

While the Cubic process, together with urethane coating, is said to be ideal for achieving a premium faux wood-grain finish, many other applications are suitable. Faux stone finishes or metallic finishes are used for architectural components and furnishings, while faux leathers and exotic or holographic treatments are becoming more popular in automotive interiors.

"Remember that automotive interior components are normally painted in a low-gloss, not a high-gloss clear coat," said Mr. Braniff. "Our challenge is to take an exterior high-gloss coating, apply it on interior surfaces and meet the cosmetic standards required. We can match the finish of an ABS console to that of a phenolic ashtray. We can even print an exotic wood finish on a not so exotic wood."

Future enhancements to Spectrum's Cubic system will include additional robots for parts transfer. The company is building a new plant, which is scheduled for completion late in 1997. The plant will house a more elaborate finishing system, which has been designed to keep up with the growing demand for Spectrum products.