What are common fluidized bed powder coating process parameters?
There are no common parameters in the process of fluidized bed powder coating since it changes dramatically with part thickness. Two-inch thick bar stock can be coated with functionalized polyethylene by preheating to 250°F, dip coated and will most likely flow out without any post heating. Conversely, thin expanded metal may have to be preheated to 450°F to achieve the desired coating thickness, and then post heated at 350°F for four minutes to complete the flow out. We have never been able to come up with coating parameters that work for everyone. Ovens are different, and parts cool down at different rates. Substrates, line speeds and environmental conditions all vary as well.
Here are some nominal starting points—take an average part of fabricated wire such as a refrigerator rack. Preheat it for six min at 500°F and then (within 10 seconds of heating) dip it for six seconds. Post heat it for one-and-a-half min at 350°F. This will normally produce a film build between 10–12 mils. On applications such as bike racks, where 30 mils of coating are desired, heat the part for six min at 550°F, dip it for 30 seconds and post heat it for one-and-a-half min at 400°F.