1. Start by looking for issues with the system and wiring.
Make sure the calibration number setting on the temperature controller corresponds exactly to the kind of thermocouple. Prevent systemic temperature measurement problems by avoiding mismatched calibration numbers.
Verify that the thermocouple model and the compensating wire match. Don't replace the compensating wire with regular copper wire. Additionally, make sure there are no loose, oxidised, or poorly connected terminals.
Measure the insulation resistance between the shielding layer and the thermocouple poles using a multimeter. Look for interference from the grounding loop and installation leaks. Install a signal isolator if needed to get rid of interference.
2. Check the thermocouple's functionality.
Using a multimeter, measure the thermocouple's circuit resistance and compare it to a qualified thermocouple with the same specifications. A hidden solder joint problem is indicated if the resistance divergence is greater than 20%.
Measure the output thermoelectric potential after submerging the thermocouple in a mixture of ice and water. On the relevant calibration table, compare it to the standard thermoelectric potential at 0°C. The thermocouple wire material has deteriorated if the variation is more than ±0.1mV.
3. Resolving Installation and Operating Condition Compatibility Problems
To make sure the insertion length satisfies the requirements for temperature measurement, check the depth of the thermocouple insertion into the hot runner. Steer clear of incorrect installation, which could result in the temperature monitoring point being distant from the heating area.
Examine the thermocouple protection tube's surface for interior moisture and scale accumulation. Lower-than-expected readings and a delayed temperature response can result from scale and moisture impeding heat conduction.
4. Confirmation of Final Calibration
At the same temperature measurement location, conduct a comparative test with a standard calibrated thermocouple. Cut off the current solder junction and resolder it if the numerical deviation is greater than the permitted error range. The thermocouple should not be used again until the calibration is finished.
This troubleshooting method is ideal for troubleshooting requirements in precision temperature control scenarios with hot runners because it may swiftly identify hidden defects that appear defect-free but cause inaccurate temperature measurements.
