Products Finishing

NOV 2013

Products Finishing magazine is the No. 1 industrial finishing publication in the world. We keep our readers informed about the latest news and trends in plating, painting, powder coating, anodizing, electrocoating, parts cleaning, and pretreatment.

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Page 46 of 59

ALUMINUM ANODIZING CLINIC the engraving is and how rough it leaves the metallic surface. I personally know of anodic coatings as thick as 2.0 mils (50 micrometers or microns) that are successfully engraved in this manner. Of course, the anodic coating is actually removed in this process. By operating on a very low power setting, the YAG laser is capable of removing "color" from an anodic coating without removing the coating itself. This only has viability for darker colored coatings. The other type of laser engraver uses a combination of gasses (carbon dioxide, nitrogen and helium) to emit a wavelength of light (10.6 micrometers) that is the same as that of aluminum. Thus, the aluminum is reflective of this wavelength laser beam. The engraving mechanism then is to absorb dark colors present in the anodic coating. No anodic coating is actually removed. The rate of absorption of the color from the anodic coating is determined by the anodic coating thickness—more quickly absorbed in thinner coatings, less quickly in thicker coatings. So, if you had a black anodized coating or a Type I anodic coating, for instance, the laser absorbs the color, leaving the "white engraved" anodic surface. If the coating is clear anodized (Type II or IIB, for instance), the engraved results may be a mixed bag. With clear anodic coatings, the depth of "color" (usually shades of gray) is dependent on both the alloy and the temper of the part being engraved, as well as on the anodic coating thickness. Normally, the more coating thickness, the darker the "clear" color. High performance, next generation pretreatment For use on all steel, aluminum, galvanized surfaces with all top coat systems • Less water usage • No fash rust • Easy to use 513.874.1113 email PRODUCTS FINISHING — 45

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