Page 84 - MetalForming October 2016

Trapped plating chemicals inside of porous parts can be released during the curing process, causing pinholes and bubbles in powder coating.
Coating Parts
A plating expert shows how metalformers can help ensure proper part coating and why open lines of communication between metalformers, platers and coaters are musts.
BY GEORGE GATTO JR.
The processes of electroplating metal products and of coating those products with paints and powder coatings—both essentially the application of a new surface to a part— are basically similar, particularly in their shared emphasis on careful surface preparation. But the significant differ- ences between the processes, until fully understood, can negatively affect the suc- cessful coating of formed and stamped metal products that have been plated.
As a provider of zinc plating, zinc- nickel plating and aluminum chromate, we’ve plated virtually every type of
George Gatto Jr. is business development manager for Gatto Industrial Platers, LLC, Chicago, IL; tel. 773-287-0100, www.gattoplaters.com.
formed metal product and assembly, many of which have then been powder coated or painted. One of our primary objectives, as we work with metalform- ing companies and their coaters, is to educate them in detail about the specifics of plating as they affect the application of various coatings.
Following are two of the most com- mon and important areas where the interaction between plating and coat- ing can result in significant challenges, and the ways that platers and coaters can work together to alleviate them.
Chromate Challenge
Coaters of metalformed products know that the success of their process- es, whether involving chemical sub- stances such as paint and other coat-
ings or powder coatings, depends to a great degree on the condition of the surface to be coated. Resulting prob- lems, from poor adhesion to surfaces marred by pinholes, trapped bubbles and other defects, can quickly destroy the value of a coating and reflect neg- atively on the brand image of a coater. Consequently, coaters spend consid- erable time and effort on cleaning sur- faces thoroughly prior to coating.
Both paint and powder coaters, for example, sometimes experience adhe- sion issues when coating over elec- troplated products. As a result, even after thoroughly cleaning parts with a phosphate solution they sometimes resort to sanding the surfaces of parts to be coated by hand to provide good powder adhesion.
82 MetalForming/October 2016
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