Consistent quality and yield for powder coatings issues.
Some powder coaters have trouble getting consistent quality and yields. There are a number of reasons for poor quality and high reject rates. One of the more common issues that lead to inconsistency is poor racking concepts. If your first pass yield is inconsistent and your rejects are too high you may have a poor racking scheme. Racking of your parts needs to be thought of as tooling that fits the part and the process. If the racking is poorly designed or the racks are not well maintained it will lead to poor control of the application process.
Parts should be racked close enough to take advantage of the space available but far enough apart to allow plenty of time for the applicator to see all surfaces and get good coverage. Parts should be racked consistently and all hooks should be full. Parts should be held to provide good access to all surfaces and they should be stable in the spray zone. Powder coaters should never rack on dirty hooks because any interruption in the earth ground path will lead to a lot of rejected parts for light coat and orange peel. In addition, rejects are a waste of valuable production time, powder and money.
Special tooling for parts can be costly. Racking costs can be evaluated to determine the difference between an optimum racking scheme and a racking pattern that does not work as well. Racks can help a company be more profitable when good principles are applied to the design and the racks are well maintained.
A powder coater should evaluate what the throughput could be with proper racks. It is often possible to use a utility rack or simple hook that may not optimize the potential production. The optimum design throughput and the utility rack should be compared for productivity and reject rate so that the productivity value is understood.
Build samples to test different racking set-ups and compare the results from one option to another. It is simple math to evaluate the number of parts per foot and the number of good parts versus bad. Many companies waste a lot of dollars by using sub-optimum racks because they do not want to invest in good tooling. Also, they may not want too many different rack designs around. Evaluate the options and there is a good chance you can improve the throughput and reduce costs by using the right racking scheme. Simple hooks are fine if they hold the right number of parts and meet the other goals for good racking. But take your time to get racking right and you should find more profit.