Thermal fatigue is one of the main factors reducing thermocouple lifespan in hot runner systems. Frequent heating and cooling cycles cause repeated expansion and contraction of the thermocouple's internal alloy wires, gradually leading to material fatigue, micro-cracks, and eventual breakage. This effect is more severe in high-speed production with short cycle times and rapid temperature changes.
Low-quality thermocouples with impure alloys or weak structures suffer more serious thermal fatigue and fail much earlier. Premium mineral-insulated thermocouples use high-purity alloys and flexible internal structures to better withstand thermal stress. Laser-welded junctions further improve resistance to fatigue and extend service life.
Improper installation, such as sharp bending near the probe, increases internal stress and accelerates fatigue damage. Over-temperature operation also speeds up alloy aging and structural degradation. Regular inspection and timely replacement of worn thermocouples help avoid unexpected production interruptions. Understanding thermal fatigue mechanisms allows users to select more durable sensors and optimize operating conditions, thereby extending thermocouple lifespan and reducing maintenance costs.
