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Conveyor rust contaminates powder coating


Hi, we powder coat refrigerator size aluminum cabinets for the communications industry on a line that uses mild steel carrier loadbars on a power and free conveyor. The loadbars travel above the split top pretreatment washer but still are exposed to some vapor from the alkaline wash, iron phosphate and rinse stages. Over time small amounts of rust/dried chemical residue flake off the loadbars contaminating the powder coating.

  1. What are ways to improve this situation?
  2. Can the loadbars be coated with some magic elixir to minimize the accumulation of crud?
  3. What are effective ways to clean the loadbars either on or off line?

We appreciate you help.

Roger M Howard
- Omaha,NE

First of two simultaneous responses


Ways to improve the situation include replacing the loadbars with stainless, designed in such a way that they trap the falling particles. Or you could try to limit the amount of material that builds up on them by modifying the top of the washer, air-flows, and sprays and temperatures. If you coat the load bars, you'll have to keep the coating fresh & clean, if you install an in-line cleaning system like Kolene makes you'll have perfect racks, but some capital up front.

Your best option may simply be hand cleaning the load bars daily. Depending on the type and size of loadbar, and the composition of the buildup, you may be able to wire brush them and send them through your washer on racks for cleaning. What you have to do is determined b your quality requirements. Get your washer, equipment, and maintenance people involved, this is a constant headache in a lot of plants, but it can be fixed with effort and maintenance.

Jeff Watson
Jeff Watson
- Pearland, Texas

Second of two simultaneous responses


Roger, First minimize the exposure of the cleaners and chemicals to the hangers. I assume you have worked on this already. The temperature, ph, and concentration all affect this problem. Make sure that these parameters are correct. If they are excessive to solve some other problem, then solve the problem another way. Second redesign the hangers. "C" shaped hangers and sanitary trays may be needed to keep contamination from the product.

Stainless Steel materials can solve the problem if they are rusting and the rust is flaking off. Stainless will also hold up longer if you are using a heat process for cleaning the hangers of paint or powder. This should be done often enough to maintain an adequate ground.

Third, there are conveyor cleaners available. They are mechanical devices that will clean the conveyor as often as needed. They will need some deign work to make them work with your hangers. Last, there is no "magic elixer". Perserverence and hard work will get you through. Randal Rockwell

Randal Rockwell
Rockwell Engineering Solutions - Mishawaka, Indiana

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