How to Conduct Thermal Cycling Life Testing for Hot Runner Sensors

There are two types of factory-side thermal cycle life testing: a streamlined procedure for inbound inspection and a full-process R&D verification. These two options address various needs:

I. Type testing and full-process R&D (Standard Specification Version)

Complete replication of real operational circumstances, appropriate for third-party certification or new product development:

1. Initial Setup

Tooling: A standard hot runner test mold with a reserved sensor attachment location of the appropriate size;

Equipment includes a digital multimeter, a standard pressure calibrator, and a programmable temperature control system with an accuracy of ±5°C;

Pre-processing: To finish the initial calibration, heat the sensor to its nominal maximum operating temperature after installation and hold it there for an hour. As baseline values, note the starting zero point, full-scale accuracy, and sensitivity.

2. Procedure for Cyclic Testing

The parameters for a single cycle are set as follows: "10 minutes to heat up to the maximum operating temperature and hold → 10 minutes to cool down to room temperature (25℃) and hold";

Start Automatic Cycling: Standard sensors need 500 cycles, whereas high-end sensors need 1000–1500 cycles;

To check accuracy, pause every 200 cycles and note the full-scale variation and zero-point drift.

3. Acceptance Standards

For the exam to be deemed qualified, the following requirements must be satisfied after all cycles are finished:

No Leakage: There is no molten material penetration at the sensor tail or adhesive leakage in the hot runner;

Maintaining Accuracy: Full-scale variation still satisfies nominal accuracy, zero-point drift ≤0.1%FS, sensitivity drop ≤5%;

Structural Undamaged: No abrupt changes or disconnections of the output signal, no cracks in the diaphragm.

II. Streamlined Factory Incoming Inspection Procedure (one-day completion, appropriate for batch verification)

Quickly identify products that don't meet thermal shock resistance requirements without requiring thousands of cycles:

Place the sensor on a hot runner that isn't being used, then heat it to the highest temperature that is typically used in production, holding it there for half an hour;

Turn off the water quickly, let it cool to room temperature, hold it there for 15 minutes, then continue this process 50 times;

Recalibrate and compare with the original settings after the cycle. It is (qualified) if the deviation is less than 0.2%FS and there is no adhesive leakage.