Step 1: Check for installation and communication issues.
Check the thermocouple's depth of insertion into the hot runner channel to ensure that the sensor end is entirely in touch with the channel wall. The distance between the sensing point and the channel wall should not be more than 10mm. Avoid probe suspension, which might lead to thermal conduction problems. These difficulties can cause discrepancies of up to 8℃ in actual measurements.
Re-sand the oxide coating on the thermocouple terminals. Ensure that the compensating wires are properly connected (positive and negative terminals are not reversed), and that the terminals are firmly crimped with no concealed loose connections. Eliminate signal transmission errors caused by improper electrical connections.
Step 2: Inspect for environmental and interference issues.
Check to see if the thermocouple signal and power lines are routed independently. Make that the temperature controller signal shielding grounding resistance is less than 4Ω. To eliminate power frequency interference, disconnect electromagnetic interference channels from high-power equipment such inverters and servo motors, which can cause reading fluctuations of 0.5-2℃.
To avoid environmental temperature field interference, position the thermocouple away from direct sunshine, cold air, and other external heat sources.
Step 3: Parameter and System Deep Correction
Verify the Husky temperature controller's thermocouple calibration settings to ensure a precise match with the real thermocouples, hence preventing systematic temperature measurement discrepancies caused by mismatched calibration values.
Repeat multi-point calibration, completing comparison tests at three common temperature points (20%, 50%, and 80% of the range). To eliminate nonlinear temperature measurement errors from thermocouples, record error values at each point and create a linear compensation curve.
To correct systematic errors caused by cold junction temperature drift, adjust the cold junction compensation settings using the recorded ambient temperature at the cold junction connection as a reference value. Maintain a temperature deviation of ≤ ±0.5℃.
Final Closed Loop Verification
After rectification, run at a steady temperature for 2 hours, comparing temperature measurements with a standard thermocouple along the way. Check that the reading deviation is ≤ ±1℃, temperature fluctuation is ≤ ±1℃, and there are no drift leaps. This entirely eliminates the issue of inaccurate temperature readings despite the thermocouples remaining intact.
This troubleshooting procedure addresses 99% of on-site instances in which thermocouples are intact but temperature readings are wrong, and it can quickly restore the temperature measurement accuracy of Husky temperature control systems without replacing hardware.
