ASK THE EXPERT: Powder Coating Color Change
27. April 2012
Q. Are color changes for powder that are under one minute really possible? I spray all manual in one booth, but I have automatic guns in the other one, and we do reclaim some of our colors, but not all of them. M.G.
A. A single powder gun can be color changed by one person in less than one minute. It requires the right equipment to be able to quickly purge the gun interior and switch over to the new color, but it is possible. You can use a box feed system and clean the gun up, change the box and then start the new color. Or, you can use a manifold with a switch system and a series of dedicated feed hoppers for even-faster color change times.
Keep in mind that the actual color change time is partly dependent on how close the parts are racked. You may be able to physically change the gun over, but you cannot discharge a color too close to a part that is not supposed to be that color. If you are cleaning the gun and next part is only a couple of feet away, you will get some of the powder on that fresh part. Or if a coated part is still leaving the booth, you could get some of the new color on the trailing edge. Realistically, you can change the gun in around 20 or 30 sec, but the spacing is most likely going to be greater due to the risk of cross contamination.
Now, if you have the clean the booth walls, or if you have automatic guns, or if you intend to recover the colors for reuse, the game changes. Automatic guns can be purged automatically using a manifold system and a color-feed center. Booth walls can be cleaned more quickly if the booth construction is designed for fast color change. In a best-case scenario, you can go from reclaim color to reclaim color in 10 to 15 minutes with automatic guns. You can go much faster if you do not reclaim. These booths use cyclone recovery systems to avoid the time involved in moving collectors for reclaim colors. The cyclone itself does not necessarily speed up color change time unless it is fitted with the right features.
It all depends on what you need in terms of reclaim and what equipment you buy. You can get some very fast times if you invest in the right equipment.