Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 103 of 707

chemical surface preparation AQUEOUS WASHING SYSTEMS BY EDWARD H. TULINSKI JENSEN FABRICATING ENGINEERS, BERLIN, CONN.; As we enter the new millennium aqueous washing systems have become the dominant method of cleaning in the industrial marketplace as manufacturers strive to become environmentally compliant. To claim that aqueous systems have come into their own market niche is an understatement. Aqueous systems clean better, meet higher cleanliness tolerances, and perform at higher production rates than traditional solvent cleaning systems. Aqueous cleaned parts are film and residue free. For an aqueous system to be successful proper equipment and process selec- tion or configuration is necessary. This is best achieved by interaction between the end user and the chemical and equipment suppliers. DEFINITIONS It is important that the end user establish some ground rules or definitions that the equipment is to be designed around. The end user must define the following: Parts The end user should define the part or parts, their maximum size, and geometry. It also should be determined whether, during the cleaning cycle, parts can come in contact with one another, or whether parts must be maintained in a proper geometry, or even fixtured. Productivity The end user must determine the productivity level, in terms of parts per hour, that the system is to generate. If multiple parts are to be processed, depending upon the equipment utilized, the equipment should also be sized and designed to ensure that product flow through the machine does not cause any part mixing. Material Handling The end user should discuss how the parts are to come to the aqueous system. The manner of delivery of components, whether they are in baskets, totes, on blue steel, egg crated, or in large hoppers, may determine equipment configuration, as well as the degree and need for automation. Parts can feed into systems directly in bulk, in baskets, or in line. Acceptable Cleanliness Standard The end user needs to establish or supply a cleanliness specification. Various types of aqueous systems are geared for large particulate and oil removal only, while oth- er systems are capable of achieving high precision and low mil-pore or low total molecular weight cleaning criteria. By specifying the cleaning requirement this will also help determine the type and the configuration of the aqueous system to be utilized. Once the end user has defined part geometry, productivity, product delivery, and cleanliness specifications the type of aqueous system to be utilized can be defined. 102

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