Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 358 of 707

Fig. 5. Corrosion performance for various finishes. AUTOMATION FOR MECHANICAL PLATING Push-button or computer-controlled mechanical plating systems are now in use and available in a variety of configurations and options. They are, basically, carefully engineered chemical feed systems designed to calculate, monitor, and control much of the plating operation. It does not do away with the need for an operator at the installation, but it does cut down on the required attention time by about 50% and, therefore, provides increases in productivity. The operator must input certain data required to establish the process para- meters. This information would include the part number or code (from the computer's personalized database), the weight of the parts load, and the coating thickness desired. The system can use bar-coded work order cards, which inputs the information automatically. The computer then calculates the total surface area in the load and then the entire process cycle. A screen display shows the cyle progress (Fig. 4). When started the system signals the pumps, valves, solenoids, load cells, and meters to operate in the exact required sequence. A manual over- ride panel is part of the system, which allows adjustments to be made if needed or to take over in the rare case of computer malfunction. Use of this advanced auto- mated process provides welcomed enhancements to an established manual tech- nology. It provides improved quality and reliability of coatings; increased process speed, productivity, and ease of use; operator safety—reduced liability from chem- ical handling and exposure; environmental compatibility and minimization of waste products; historical tracking, record keeping, and documentation; and overall cost effectiveness. In an automated system, all chemicals are in liquid form including the plating metal. The powdered plating metal is transformed into a liquid slurry in a two-part metal slurry mixing system consisting of a mixing module and a delivery module. The mixing module combines a measured amount of water and metal dust under constant agitation and then delivers it to the delivery module for the plat- 357

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