Improving Cleaning Process Throughput

Q. We are a smaller fabrication shop that wet paints steel and aluminum. The business has started to grow again, and the biggest bottleneck we have is paint. Unfortunately, we are spraying and wiping down parts with thinner and acetone. We want to move to some kind of cleaning tank and/or phosphate solution. Can you recommend a system?­ –S.T.

A. The first area in your current process to be careful with is worker safety. Both solvents (thinner and acetone) will have exposure limits to them and, if atomized with a sprayer, matters could be even worse. Additionally, both of these solvents represent flammability concerns. Acetone has a flash point of about 1°F, while paint thinner or mineral spirits may consist of a variety of boiling ranges and flash points, but can be as low as about 70°F. 

Not knowing the size or quantity of parts you are cleaning, it is a somewhat difficult to recommend a single system. However, I can suggest that a phosphating system would not be advisable since you are dealing with stainless steel and aluminum. I am not aware of any phosphating formulation that actually forms a phosphate coating on stainless steel. Additionally, unless specifically formulated for it, most phosphating solutions will not form on aluminum. A manual pressure washing system is certainly preferable to what you are currently doing. Specific low-foaming, multi-metal cleaners can be used that would be compatible for degreasing.

If you want to further increase the output from this process, a cabinet-style spray washer may be able to do the job. In this scenario, you will position parts on a turntable or rack them. This is then rotated back into the cabinet where it is surrounded by spray risers with nozzles fed by a pump from the system sump. This will perform a spray wash using a cleaner fed from a dedicated and heated sump. Additionally, some systems can have a separate sump for water rinsing parts following the cleaning process. This may be the best fit for a small- to medium-size fabrication shop.