Rusting Trolley and Chain

Q. I installed a powder coating system in my plant in Ohio and the trolleys and the chain has rusted to the point that the trolleys are falling apart and the chain is rusted so bad it’s dropping rust on the coated parts. I replaced the trolleys with sealed bearing trolleys but I cannot find anything to replace the chain, the chain is a high carbon steel cast that is standard in the industry. My system is a five-stage, alkaline, rinse, iron phosphate, rinse and a halo seal, the chain and trolleys go through the washer and are covered with side guards, but they still get the misting and humidity which is causing the rusting.

Is there some kind of material or coating that I can have put on the chain? At one time they made some chain out of a Microloy material but that is not available for the three-inch chain anymore. Maybe some kind of plastisol coating that the wash won’t attack? W.D.

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A. This problem is caused by not having a generous “top of part to top of rail” space. This dimension, as the name suggests, is the space from the top of the conveyor rail to the top of the part. Industry standard is that this space be at least 36 inches, but I prefer 42 to 48 inches. Having this dimension longer, ensures that the conveyor is well above the spray zone in the washer and powder coating booth. This will go a long way to ensuring that the washer moisture and powder coating do not contaminate the chain. Most system houses that design these systems prefer that this dimension be as short as possible to keep their equipment shorter and less costly. However, when everyone bids to the same standard and the system house realizes that there is no competitive downside, they are always in favor of a generous top of rail to top of part dimension. Keep this is mind next time you buy a new powder coating system, because you can’t change it now.

For now, I recommend that you install a powered wire-brush chain and trolley cleaner and install it before an automatic lubricator before the washer. The cleaner will remove the rust and dirt build-up and the lubricator will help protect the chain from further damage. Remember to buy a heat-resistant lubricant (up to 600°F), otherwise it will just burn-off in the cure oven. While you are at it, buy a wire-brush rail cleaner as well. This will clean the entire rail as the chain pulls it around the system. Be prepares for some short-term dirt defects while you get all the junk off the conveyor chain and rail.

Lastly, you can buy a patented “Conveyor Protection System” from Protectaire (www.protectaire.com) and install it in your washer and spray booth, if necessary. This device uses a metal shield and blower system that keeps the water mist and powder coating out of the conveyor. These have been around for a long time and are very effective.