Monitoring the Internal & Peak Internal Air Temperature during the Rotomolding process

Do you monitor the Peak Internal Air Temperature (PIAT) in your Rotomolding process? If not, you should. And here’s why. Our document on monitoring Peak Internal Air Temperature (PIAT) helps explain the many benefits of this diagnostic tool and how it can improve the quality of your roto-molded parts and why every roto-molder should use it.

The ability to monitor the air temperature inside the mold is one of the diagnostic tool’s Rotomolders have available today to help optimize the Rotomolding process. The cost of monitoring equipment has become more economical in the past few years making it a diagnostic tool that molders of all sizes should have in their operation.

Today’s wireless technology makes it possible to monitor the PIAT / IAT on a variety of Rotomolding ovens and molds. Typically, the wireless transmitter is enclosed in an insulated box with cooling packs and mounted adjacent to the mold you intend to monitor. The temperature probe is normally inserted in the vent tube to protrude into the void cavity inside the mold. The processing technician would commonly set up their laptop computer with the attached wireless receiver in a safe location, typically close to the oven and oven control panel. This allows for the technician to monitor the internal air temperature in real time during the molding process.

The following is a partial list of the many benefits to monitoring PIAT:

  1. Optimizing the physical properties of the plastic. Your resin supplier can give you guidance on the optimum PIAT for each resin grade. Typically, the PIAT that polyethylene Rotomolding grade resins go bubble free optimizes the impact performance of the resin.
  2. Monitoring the PIAT during the startup of a new mold can get you on cycle much faster. This can be a tremendous cost savings as you reduce time and material loss running multiple cycles to get the new part to a proper cure.
  3. Periodic monitoring of a rotomolded parts PIAT will help determine if the oven and process conditions are running consistently. Changes in plant ambient temperature, oven maintenance issues, properly working cooling fans and water mists can all affect the PIAT data curve on the part’s standard oven cycle.
  4. Newer ovens utilizing the IRT technology need to have the PIAT monitored to properly set the oven exit temperature.
  5. Reviewing the data curve created from monitoring the PIAT will let you see the effect of cooling and mold release changes on the molding process. This is helpful in diagnosing early release issues causing warped parts.

There are several manufacturers of PIAT monitoring equipment. Single channel monitoring systems are a good lower cost diagnostic tool for most production environments. Multi-channel monitors allow for checking multiple molds on one ARM or a variety of temperature measurements during a single cycle. Multi-channel monitors can be used to check temperatures of the internal air, oven temperature and mold temperature at the same time.

If you have any questions or need additional information on the advantages of measuring PIAT / IAT please contact your Entec Polymers Sales or Technical Representatives.

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