New Film Insert Molding Technology Dresses Up Auto Wheel Covers.

* New film insert molding (FIM) technology is being used to make auto wheel covers and center caps that reportedly outshine and outperform chrome-plated or painted plastic and metal counterparts. These products utilize a new poly-carbonate film laminate structure that boasts chemical and uv resistance, along with specially developed high-temperature inks.

Up to now, a two-color emblem on a center cap has been considered a high-end decorating option. However, this new FIM technology reportedly makes a wide range of multicolor designs available at equal or lower cost than traditional decorating techniques with more limited graphics capabilities. FIM uses standard injection molding equipment and screen-printing services, and it eliminates painting or plating. Savings are said to be greatest when multiple colors are used together with chrome accents.

Three years in the making, this patent-pending technology is a joint development of Bayer Corp.'s Plastics Div. in Pittsburgh; McKechnie Vehicle Components of Troy, Mich.; and Angell Manufacturing Co. of Dayton, Ohio. The technique is trademarked InserClad by McKechnie, which molds and markets the products. Screen printer Angell provides the decoration, while Bayer supplies the film and backing resin, plus FIM processing expertise. The three firms hold joint ownership of the technology.

Second-surface printing

InserClad utilizes second-surface printing, in which the graphics are printed on the back or inside surface of the film, where it is permanently protected from the environment after the part is molded. On the other hand, this approach exposes the ink to greater heat from direct contact with the molten plastic backing.

High-temperature inks are thus essential to the success of the process. InserClad is based on Bayer technology for formulating inks for printing on polycarbonate. These inks use Bayer's APEC high-temperature polycarbonate as the carrier for the pigment particles. These inks can withstand the high melt temperature of the injected resin, in this case a PC/ABS blend, as their glass-transition temperature exceeds that of the backing resin.

Angell screen prints the graphics onto a clear, 0.02-in.-thick sheet of Bayer's new Macrofol DPF-5003 polycarbonate multilayer film structure. Mark Witman, director of plastics technology at Bayer, says this laminate's bottom layer, on which graphics are printed, is polycarbonate-based, while the top layer is a special fluoropolymer that provides chemical and uv resistance.

According to Tim Garwood, Angell's v.p. of design engineering, InserClad allows the firm to print multiple colors, transparent colors, and half-tones. Adds Robert DiMarco, technical sales manager for McKechnie, "The technology allows you to put virtually anything you want on a wheel cover or center cap. Multiple colors are easy to accommodate, and emblem registration and indexing are problem-free."

Angell thermoforms and trims the printed film into the three-dimensional shape of the final part and ships the formed inserts to McKechnie. The molder places the insert in a mold and injects Bayblend T 85 PC/ABS resin behind it.

McKechnie offers InserClad as an option on all new vehicle programs. The flexibility to change graphics from day to day is one advantage of the technology. Better wear resistance and color repeatability than paint or electroplating are claimed for InserClad decoration. The new film's abrasion resistance is reportedly equal to high-quality automotive finishes, and it has stood up to three years of weather testing under the Florida sun.