Appliance Design - September 2008 - (Page 48) DECORATION applied. For instance, Goodrich Technology deposits a layer of nickel chrome first, and then a layer of chrome. The thicknesses of the two layers averages around 1,500 angstroms, but can range in thickness on a part depending on whether it is a 3D part because PVD is basically a line of sight process. The surface directly facing the target will receive the most metal. While theoretically, only the substrate facing the target would receive the materials, in reality other surfaces will receive some coating as the metal atoms are bounced off of each other and the other ions in the glow discharge. The PVD process allows for a durable end product. Colahan says that in his in-housing testing, the PVD coated parts were scribe marked down to the base substrate prior to testing. By doing this, each layer is tested, as well as the entire layer structure. So far, the process has been able to withstand the tests. For instance, Colahan says that one part was scribed marked and then subjected to more than 1,000 hours in a salt spray test. This far exceeds most requirements. In fact, a traditional chrome-plated part would only have to undergo 66 hours of testing, without a scribe mark, and most chrome today has a difficult time doing that, Colahan says. The final step of the process is to apply a clear topcoat, which is typically an acrylic. This coating is used to protect the chrome layer and can be tuned to the appropriate application and give it properties for that use. The acrylic coat often used isn’t as resistant to showing scratches as say molded in plastic, however, but various top coats can be used to meet specific requirements for greater resistance. For automobile wheels, Colahan says they use a powder with good impact and UV resistance, but it does not have as good of scratch resistance as traditional chrome. For more scratch resistance, a harder coatings material can be used, but impact resistance can be sacrificed, he says. Decorative laminate films also use a clear topcoat for protection. The films come in laminate form, sandwiching a thin coat of chrome metal between the clear coat and a substrate layer that contacts the component being fabricated. The films are especially appropriate for 3D parts as they can be stretched around a contour or other dimensional feature. Some films feature a metal layer that is so thin, that manufacturers can print on the backside of the film and backlight the decorative piece for use as a nameplate. By day, as light strikes it, the decorative part looks like chrome, but when the light level drops, it shines with the printed image when the backlight shines through. Two companies offering this technology include Sheffield Plastics, Sheffield, Mass., a subsidiary of Bayer MaterialScience, and Soliant LLC, Lancaster, S.C. Sheffield’s recently introduced Makrofol 3D Metallic FG film that comes in either bright or low-luster matte. The top surface is a polycarbonate that offers increase scratched resistance, says Ted Trautman, principal product and process technologist at Sheffield Plastics. It is available in thicknesses of 0.008 in. or 0.013 in and can be formed in a highpressure forming (HPF) process. Bayer’s film is typically applied through a Thinner is Better Problem: Provide overcharge and short-circuit protection in the tight confines of today’s rechargeable battery packs. Solution: 1 Involve a Pepi sales engineer 2 Choose the right control 3 Customize to meet application needs ® The Pepi® Model V is only 0.061” thick, but provides maximum protection and minimal power drain due to low internal resistance. We have many reliable solutions that fit in small spaces. To find the one that’s right for you, call or visit our web site. www.pepiusa.com Only Pepi® thermostats and thermal protectors offer so many options in fit, configuration, cost and customization. For a close look, send for our new Disc-Type and Conductive-Type Catalogs today. www.pepiusa.com Portage Electric Products, Inc. N. Canton, OH U.S.A. salesinfo@pepiusa.com • 1-888-GO4-PEPI 48 applianceDESIGN AD06084Port.indd 1 September 2008 5/15/08 9:59:12 AM www.applianceDESIGN.com http://www.pepiusa.com http://www.pepiusa.com http://www.pepiusa.com http://www.appliancedesign.com
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