Industrial Automation and Motion Control Blog | The Knotts Company

This post is brought to you by Proportion-Air.

Looking for a better way to cool zones of their wheel molds with air, an automotive aluminum wheel manufacturer was using water for some of the zones and air for others in each mold. Their air cooling set up consisted of manual regulators and pressure gauges for each air zone.

Unsurprisingly, they were unable to achieve consistent cooling results. Additionally, there was no way to know if the zone had a leak or ruptured hose (air was plumbed into each zone via one inch rubber hose). Hoses would wear and leak due to heat and flexing when the mold was opened and closed.

Closed Loop Solution

To address the problem, Proportion-Air took their closed loop flow controllers and specially calibrated them 5.6-20mA=7.5 to 75 SCFM. When installed, this assembly allowed the customer to tightly control temperature in the individual cooling air zone and monitor flow in the zone at all times.

If a hose leaked, the closed loop flow controller compensated for the leak to be sure the zone had enough air to maintain the correct temperature. If the hose leak exceeded the flow required, the analog monitor signal from the flow controller showed that the controller failed to achieve the set point request. The customer’s PLC controller was programmed to alarm when the command and monitor did not match and that wheel was scraped. The alarm also alerted the operator to replace the failed hose.

Periodically, a pinched cooling zone hose would also be an issue. If the hose was pinched, not enough flow was achieved and the flow controller monitor would show the PLC that flow was not achieved. The PLC alarm would notify the operator of the issue so corrective action could be taken. This issue was resolved as well.

Periodically, a pinched cooling zone hose would also be an issue. If the hose was pinched, not enough flow was achieved and the flow controller monitor would show the PLC that flow was not achieved. The PLC alarm would notify the operator of the issue so corrective action could be taken. This issue was resolved as well.

Problem Solved

Proportion-Air’s specially calibrated flow control package was the right fit for this manufacturer’s needs. Among the benefits realized by the customer:

• Flow output from their flow controller was linear and proportional based on the PLC’s command signal input and there was no linear relationship between their previous pressure regulator flow system.
• The flow controller was closed loop and it was therefore able to compensate for situations where things changed downstream changed in the zone, such as a leak.
• A signal from the Proportion-Air flow controller’s flow transducer allowed flow to be monitored in the system in real time by the PLC.
• The system allowed for more consistent and repeatable quality.
• The system substantially reduced scrap.
• The PLC driven closed loop flow controller eliminated operator input ensuring that product was made the same regardless of which operator was working.

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