Getting the hex outta here - WIP - North American automotive finishing industry affected by EU rules

Automotive Design & Production, Dec, 2002 by Kermit Whitfield

End of life regulations enacted by the European Union to remove toxic substances from the automotive supply chain are having far-reaching effects on the North American automotive finishing industry. As automakers continue to become more global in their parts-sourcing strategies they are insisting that suppliers on this side of the pond meet stringent European standards. One such standard is the elimination of hexavalent chrome, which has been used for decades as a cost effective pretreatment agent for both steel and aluminum. According to John Scharf, manager of strategic industry marketing at the specialty chemical company MacDermid Inc. (Waterbury, CT), European regulations require the complete elimination of hexavalent chrome in vehicles by July 1, 2007. But in order to meet this deadline most automakers are setting an internal deadline of 2005, which effectively means that any new part being designed today must be free of the substance.

With this in mind, MacDermid has developed pre-treatment alternatives that meet end of life strictures. One alternative is a conversion coating for zinc-plated steel parts like fasteners. Current practice calls for the parts to be plated with zinc, and then dipped in a chromic acid solution. The zinc reacts with the hexavalent chrome in the solution to form an outer coating that inhibits corrosion. MacDermids process uses trivalent chrome suspended in a matrix of organic acids as the dipping solution in order to achieve the same end in a more eco-friendly manner. And lest it be thought that MacDermid is just trading one problem for another: the difference between hexavalent and trivalent chrome is considerable. The former is a known carcinogen while scharf says the latter "is found in most multivitamin supplements."

However, the health and environmental advantages of this process come at a cost. The organic acids needed are more expensive than the cheap and abundant hydrochloric and sulfuric acid that is currently used with hexavalent chrome. Also, according to Scharf, "Hexavalent chrome reacts at room temperature, but for trivalent the reaction must be driven by heat rather than raw chemistry." So suppliers using this method will have to invest in heating equipment.

That is, if they choose to get rid of hexavalent chrome at all. Because end of life laws allow absolutely none of the compound, finishers that use it for non-automotive products, which do not have the same restrictions, must keep tanks and processing equipment strictly separated, lest the auto parts become contaminated. This could prove so burdensome and expensive that some companies may abandon the automotive sector altogether. But since European legislators are now considering extending end of life laws to other industries, suppliers may want to invest now, and eliminate hexavalent chrome rather than be forced to do so in a few years. If so, the environment would benefit and so would companies like MacDermid.