Understanding Fluidized Bed Powder Coating
For more than 50 years, fluidized beds have been used to coat parts with powder coatings. In this article, two industry experts tackle some common questions about the fluidized bed process…
Q:What are the key differences between “fluidized bed” and “electrostatic fluidized bed”?
With fluid bed coating, the part has to be preheated, immersed in the coating and then flowed out.
Electrostatically assisted fluidized bed coating does not dip the part into the powder, it generates a cloud of charged particles (much like a conventional electrostatic gun) through which a heated or an unheated part passes. It generally applies a thin coat vs. the thicker coat from fluidized bed coating.
Q: What are some other benefits of fluidized bed powder coating?
There is generally less waste since it’s a 100% transfer efficient coating method. When compared to electrostatic spray, capital investment in equipment and ongoing maintenance is most always lower. It’s basically a low-tech coating method, and once coating parameters are established, there are not that many things that can go wrong. It is by far the most efficient method of applying thick film coatings.
Productivity increases are very common when switching to a fluidized bed coating process. The ability to coat an entire rack of parts by a single dip into the coating tank can be very efficient.
Q: How do I know if fluidized bed powder coating is a good fit for my products?
There are several questions that need to be asked. First, since fluidized bed coating generally applies a thicker coating, can the end part withstand the dimensional changes? Unlike electrostatic coating, fluid bed coating will generally smooth over any small details in the parts, such as embossed serial numbers, metal imperfections, etc. This can be extremely beneficial for parts where Faraday Cage effects are problematic. Welded wire products are good examples. Electrostatic spray has a hard time getting into the depths of the wire cross welds, whereas fluidized bed coating, due to the larger heat mass of the overlapping wires, encapsulates the entire weld.
Also, part complexity and geometry should be considered. If you have the right configuration, fluidized bed coating can be the way to go. Parts that will allow the excess powder to fall off the part work great. Others—with areas where trapped air or excess powder that will be difficult to displace—should be avoided.
