How to Determine the Interchangeability Error of Hot Runner Sensors

Determining the interchangeability inaccuracy of hot runner sensors mostly involves "comparing the temperature measurement deviation before and after the swap." A standard calibration procedure or a quick on-site comparison method can be used for this. The following are the particular techniques of operation:

 

1. Quick On-Site Judgment Method (no extra equipment needed, ideal for quick testing during manufacturing)

The judgment can be finished in ten minutes using this procedure, which is the most popular in production scenarios:

Maintain a constant mold temperature while recording baseline data. Record the stable temperature T1 that the temperature controller displays once the current sensor temperature data has stabilized. At the same time, look for any temperature-related flaws in the product's quality.

swap out for a sensor with the same specifications: Install a new sensor with the same model and specifications after removing the old one. Reheat the mold while maintaining the same heating parameters and waiting for the temperature to stabilize, which should take ten to fifteen minutes.

After the swap, note the temperature and compute the deviation: After stabilization, note the new sensor's reported temperature T2 and compute the deviation value:

ΔT = |T² - T 1 |;

Conclusion:

ΔT≤±1℃: Direct use of interchangeability error is permissible;

±1℃＜ΔT≤±3℃: An error has occurred. The temperature control compensation coefficient must be adjusted for precision injection molding. It is possible to employ regular injection molding;

ΔT＞±3℃: There is too much interchangeability error. It is not advised to use. Before retesting, the preload must be changed or the sensor must be replaced.

 

2. Standard Calibration Judgment Method (more accurate findings, appropriate for high-precision applications)

It is appropriate for batch verification of new precision injection molding sensors and only requires basic auxiliary tools:

Set up a standard thermocouple that has already been calibrated, insert it into the hot runner mounting hole, and note the steady temperature T_standard at the bottom of the hole;

While maintaining a steady heating temperature, install the sensors of the same specification to be tested one after the other into the same mounting hole. Once the temperature has stabilized, note each sensor's indicated temperature Ti;

Determine each sensor's deviation from the standard temperature ΔTi = |Ti−T_standard|, and concurrently determine the difference between any two sensors;

Conclusion: The interchangeability error is acceptable if the maximum deviation between all sensors is ≤ ±1℃; if the maximum deviation is > ±2℃, the interchangeability error does not satisfy the high-precision standards.

 

3. Auxiliary Judgment: Product Quality-Based Reverse Verification

Reverse judgment can be made using product quality if interchangeability has been completed and direct temperature comparison is not feasible: The interchangeability error is within acceptable bounds if the product does not show temperature-related flaws such color difference, dimensional variations, or missing glue/burst after steady production. If temperature changes are more than ±3°C and temperature-related faults are common, the interchangeability error is too high, necessitating sensor replacement or modification.

Quick Judgment Summary: Due to their simplicity and effectiveness, on-site rapid comparison techniques should be given priority in production settings. For more precise findings, employ the standard calibration procedure for high-precision batch verification. It is not advised to employ errors more than ±3°C in precision injection molding situations.