What is the thermal cycle life test for hot runner sensors?

One essential sign for confirming hot runner sensors' anti-aging capabilities is thermal cycle life testing. It predicts the sensor's actual service life and accuracy retention by simulating the thermal shock of frequent start-up and shutdown in real production. The following are specific test requirements and evaluation standards:

1. Core Test Goal: To replicate the repeated thermal shock of "heating up for production → cooling down for shutdown" in a hot runner system, confirming the accuracy stability, diaphragm fatigue resistance, and sealing reliability of the sensor following extended thermal cycling, thereby eliminating unsuitable products beforehand.

2. Standard Testing Protocol:

Installing the sensor in a typical hot runner fixture is the first step. To finish the initial calibration, heat to the maximum operating temperature (usually 350°C) after wiring and hold for an hour. Note the full-scale accuracy and the starting zero point.

The cycle of "heating to operating temperature and holding for 10 minutes → natural/forced cooling to room temperature and holding for 10 minutes" should be repeated.This is one cycle. More than 1000 cycles are typically needed for high-end sensors, which equates to more than three years of frequent startup and shutdown in actual production. Final Inspection Decision: Once the necessary number of cycles have been completed, recalibrate the measurement and compare it to the starting parameters: zero-point drift ≤ 0.1%FS, full-scale accuracy deviation still satisfies nominal standards, and there is no seal leakage; the test is deemed qualified. Unqualified results include excessive drift, seal leakage, or a sensitivity drop of more than 5%.

3. Variations in Acceptance Criteria

Common consumer-grade injection-molded sensors have an actual lifespan of one to two years and require 500 cycles to pass;

High-end corrosion-resistant models, such as the Kistler 6125A, pass 1500 heat cycle tests by default, which translates to an actual lifespan of three to four years with repeated start-stop cycles, guaranteeing increased stability and precision.