What are the symptoms of hot runner sensor aging?

Reduced stability, shorter response times, and decreasing temperature measurement accuracy are the main signs of hot runner sensor aging. In particular, these can be divided into two common manifestations: abnormalities in temperature measurement and abnormalities in production.

1. Common Signs at the Temperature Measurement Level

Type of Symptom

Particular Expression

Constantly Raising Deviation

Under the same procedure, the difference between the melt temperature and the displayed temperature progressively rises from less than 5°C to more than 10°C. The installation position cannot be lowered to the acceptable range, even after calibration and adjustment.

Significantly Slow Reaction Time

During heating, the reading increases more than 30% more slowly than with a brand-new sensor. Temperature control adjustments always lag behind changes in shear heat generation, and therefore is unable to track brief temperature changes during high-speed injection molding.

Fluctuations in Irregular Curves

The temperature graph, which was initially smooth, shows numerous little leaps, and the range of fluctuations increases from ±1°C to ±3~5°C. Process modifications do not completely eliminate this variability.

Quick Inaccuracy Following Calibration: After just one or two weeks of production, the deviation surpasses the norm once more, making long-term accuracy maintenance unfeasible.

2. Signs Associated with Production and Product Levels

Symptom Type-Specific Signs:

Continuously Increasing Defect Rate: Short shots, uneven filling, and multi-cavity imbalance are common occurrences that cannot be reliably reduced by changing process parameters.

Instant Product Quality: Frequent visual flaws such shrinkage marks, warping, color variations, and flow marks, as well as excessive variations in important dimensions.

Frequent Equipment Alarms: Frequent false alarms from control chambers that are either too hot or too cold might cause inexplicable shutdowns and reduce production efficiency.

Progressive Problem Amplification: Issues progressively worsen from small to serious, are first challenging to identify, and may ultimately result in mass discarding.

It is usually accepted that the sensor has aged and failed if it has been in operation for three to five years and shows two or more of the aforementioned indications.