Metal Finishing Guide Book


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Fig. 4. Multirectifier computer-controlled system. to adjust the voltage and on-and-off times of the positive and negative portions of the output independently. This provides the maximum amount of flexibility to generate the broad range of colors available through electrolytic coloring. COMPUTERIZATION In the 1970s many metal finishers investigated modifications that would be required to upgrade their rectifiers to computer control. At that time, however, the price and risk of automation was too high for most companies, forcing them to continue using manual control. Today, the importance of incorporating some degree of automation into the metal-finishing processes is becoming more evident. For example, smaller firms find themselves at a disadvantage when competing against larger, more automated companies, especially for jobs where the finished parts require precise coating thickness and consistent finish qualities. Additionally, certain plating applications require multiple layer applications to achieve the desired coating thickness and surface quality. These multilayer processes demand extremely accurate and repeatable coatings. The major advantage of computer over manual control of a rectifier is the computer���s ability to repeat a particular operation or procedure time after time. Computers can perform a variety of different functions when integrated with rectifiers. The computer can simultaneously monitor a number of output currents and voltages, detailing them on a video-display terminal. It can also maintain those voltages and currents within designated parameters, thereby compensating for varying input voltage or load changes. The computer can easily regulate pulsing and reversing power supplies. The computer replaces 775

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