Powder Coating On Coil Stock

Q. Can you describe the process of coil powder coating to me? What are its finishing products? Its application? What do I have to watch out for on the backing of the finished application? (i.e., the side that’s not coated?) S. K.

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A. Coil coating a metal substrate using powder coating entails the same process steps as any other powder coating operation. The substrate must be cleaned and pretreated, dried, cooled, powder coated and cured.

The only difference is that the product being coated is a continuous coil of metal and not individual parts. Now, granted, most coil coating operations run the coil at very fast line speeds (up to 150 fpm) requiring that the curing operation be accomplished very quickly using IR or near-IR.

Basically, the coil is unwound and threaded through a system of rollers and accumulators to allow for non-stop operation. The substrate is transported horizontally for coating/curing and vertically for cleaning, pretreating, and drying. Think of a paper mill or a newspaper printing press for the visual of how this might look.

This method of powder coating can process a lot of material in a very short period of time and is performed usually by a steel supplier providing pre-coated stock to various manufacturing companies. The back of the substrate can be coated or left uncoated, as desired. If it is uncoated, then it is often treated to prevent rusting.

The size and cost of this equipment usually makes installing this type of system only practical by steel suppliers or aftermarket steel jobbers. So if you are interested in this process, you had better have a boatload of cash.