Technically Speaking: Address Potential Part Failure NOW

Posted on Saturday, December 1, 2012

Welcome to my inaugural column of Technically Speaking. In each issue of Powder Coated Tough, you will find me, here, offering tech service know-how to our readers. One question I often hear is: What is going to happen to my part after it has been coated? And why should the coater I choose care?

This month’s topic is often a neglected issue until it’s too late. In the world of coating parts for others, the coater tends to focus on the part while it is in their hands, with an emphasis on proper pretreatment, powder application, curing, and careful packaging for shipping. Then, sometimes after six months to a year passes, an angry customer returns with news of coating failure out in the field. The substrate is rusting through the coating, the coating is coming off in sheets, and the customer is looking at you for answers.

You, the coater, look at your daily production logs on the dates that you coated the parts. Everything is in order. So you ask the customer to see the failure. They produce a picture of the part in the field. After carefully scanning the picture of the part looking for clues to the problem, you see it. The part is bolted to a cement pad. The corrosion starts from the bolted area and creeps under the coating on the part. This creepage then leads to more exposed substrate, which causes more creepage and more corrosion. So, you ask the customer, “Did the part get cut, drilled, or bolted after the coating was applied?” After all, bolting a part can create tremendous pressure on the coated part and cause the coating to chip in the bolted area. The answer, of course, is yes. Then you ask how the [cut, drilled, or] bolted area was treated, because this exposes the substrate to the environment. The look of confusion and then anger on the customer’s face tells you that the bolted area was not treated (which, you of course had already surmised). You also mention that since any treatment in the field after powder coating is inferior to the original powder coating that regular maintenance of the cut, drilled, bolted area also is required. Additionally, to ensure field life of the part, spot inspection of the affected areas every 3 to 6 months with reapplication of any said treatment will be needed for the rest of the part’s life out in the field.

Powder coating is an excellent protective coating from the environment. But once the protective coating is cut, drilled, or bolted then you have an entry point for field failure. Now many may say that the coater is not responsible for anything that happens outside of the coater’s control. I tend to agree, but the coating community needs to be better than that. Let’s start by having written documents on what kind of performance is expected of the coated parts. This needs to include a provision about the need to treat and maintain areas of the substrate that get exposed during installation of the part. By discussing this issue before an item is even coated helps everyone to make certain that the coated part will last in its environment for the life that the customer is expecting. This will then let the protective coating work to its fullest potential.

Powder coatings are an excellent protective coating when all potential failure areas are addressed early and dealt with in the proper manner. Educate your customers and your customers will be happier with the field life of their coated parts.

Mike Wittenhagen is service technician at PCI. He can be reached via email at mwitten@powdercoating.org.