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Ideal spray patterns with maximum impingement will optimize cleaning efficiency. PRODUCTS FINISHING — PFonline.com 33 measured and monitored, and the levels should be reduced whenever possible. Ideally, the cleaning compound will reject the oils and soils, allowing removal on a continuous basis. Oil skimmers and coalescing units are typically used to remove separated oils from cleaner baths. Coalescing units outside the washer are effective because they benefit from temperature reduction and reduced solution turbulence, maximizing the separation of the oils. Operators should draw the cleaning solution to the coalescing unit from an area of maximum soil density. Units with floating "heads" are useful for measuring the amount of debris contained in the fluid. In immersion processes where parts are lifted from the tank, operators should ensure that the parts are not pulled through the floating oils, otherwise redeposition will occur. In such systems, emulsifying chemistry is a better choice. Filtration can also be used on cleaning systems to remove particulate debris such as metal chips or insoluble material. Effective soil management leads to consistent performance and extends solution life, improves quality and reduces waste. System Maintenance Routinely ensure that the mechanical action of the washer is fully operational and maximized. In spray washers, the pressure needs to be monitored, along with routine inspec- tion and proper spray nozzle cleaning. Sludge and scale in the washers, especially around ultrasonic transducers and heating elements, must be properly managed. Rust Protection Aqueous systems can incorporate rust prevention agents to protect against corrosion, both in-process and long term. Proper product selection, maintenance and an understanding of the incoming water quality are keys to rust prevention. Rust Preventive Selection Selecting a rust preventive fluid requires consideration of the process, the substrates and the degree of protection required, along with subsequent operations (if any). Many formulations exist where the product is capable of cleaning and providing rust protection simultaneously, as long as the chemistry is not rinsed. Ideally, there will be multiple stages in the process, where the parts can be fully cleaned (and the soils confined to the cleaning stage), then rinsed, followed by using the rust preventive fluid. When systems are limited to one or two stages, the soils building up and remaining on the surface of the parts should be closely monitored. This will impact both the rust protection and the performance of subsequent operations, such as bonding. Understand that seasonal changes impact corrosion protec- tion programs. In summer months when humidity levels are highest, systems require adjustments to ensure success. The floating head system is removing soils in a process washer. PARTS CLEANING