How to Calibrate Hot Runner Thermocouples On Site

Regular on-site calibration is required to eliminate hot runner thermocouple temperature fluctuation and restore precise measuring performance. Injection molding stability is significantly impacted by thermoelectric element drift brought on by prolonged high-temperature operation, which results in inconsistent displayed and actual working temperatures. Operators must halt production and allow the hot runner system to cool down slightly before doing a formal calibration. They must then arrange a standard infrared thermometer, a professional calibration instrument, and operating tools, and ensure that all temperature control zones are in a normal standby state.

Data comparison and deviation measurement are the first steps. Set preset standard temperature values for the manifold and each nozzle zone, accordingly, and turn on the hot runner heating system. Use a high-precision infrared thermometer to measure the actual surface temperature of hot runner metal parts close to thermocouple probes after the temperature has stabilized for 20 to 30 minutes. Record the observed data and compare it with the temperature controller's digital reading. Each zone's positive or negative temperature differential should be calculated individually, and thermocouples with excessive inaccuracy greater than ±1°C should be marked out.

Hardware physical calibration with an eye toward installation flaws is the second phase. For thermocouples that exhibit significant deviation due to inadequate contact, remove them entirely, thoroughly clean the mounting holes of carbon deposits, plastic residues, and oxide dirt, gently polish the probe surface to eliminate surface scale, reinsert the thermocouple to the standard depth, and securely fasten the fixing sleeve to guaranty complete close contact between the probe and heating matrix. Temperature lag and low reading errors brought on by air gaps can be successfully resolved with this technique.

The third stage involves using a temperature controller to adjust program parameters. Go into the hot runner temperature control box's system settings interface, locate the thermocouple compensation parameter menu, and enter the recorded actual temperature difference value for both positive and negative offset compensation. For instance, set a negative compensation value to update data synchronously if the shown temperature is 5°C greater than the actual temperature. Modifying heating power carelessly to hide thermocouple measurement mistakes is prohibited.

To guaranty steady results without recurring drift, conduct constant temperature verification two or three times after calibration is finished. It is usual practice to perform comprehensive accurate calibration once every three months for high-precision mold production lines and full-range thermocouple calibration every six months in mass production workshops. The service cycle of thermocouples can be maximized and hot runner temperature management can always be maintained within the most precise range with scientific on-site calibration.