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Aluminum anodizing system controlled
with help from D2-260 PLC system and
Text panel

by C R Williams,
Robo Systems
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Our system controls aluminum anodizing. The operator uses a text panel to enter the size of the job and the desired thickness of anodizing. The D2-260 translates this into the necessary current, voltage, and time profile required to produce the desired result, and controls a 300kW SCR switched power supply that delivers the anodizing current to the workpiece. Since the optimum waveform has both short term (~1sec) and long term (~5min) components, and needs precise control over two orders of magnitude (10A to 1000A), the floating point math capabilities of the D2-260 are used quite heavily. The environment is extremely noisy electrically (because of the 300kW SCR phase angle switching), so the design of the grounding and shielding, as well as software filtering, were very important to the success of the project.

In addition to the standard PLC on/off inputs and outputs, analog inputs and analog outputs are used as part of the monitoring and control process.
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