Melt viscosity directly determines the flow behavior of plastic in hot runner systems, and thermocouples are the key component that maintains its stability. Viscosity is highly sensitive to temperature: even a small temperature rise will reduce viscosity, leading to flash and overfilling, while a temperature drop will increase viscosity and cause short shots. Thermocouples provide real-time temperature feedback so the controller can keep melt viscosity within the ideal processing range.
In consistent production, stable thermocouple signals ensure that each shot has the same flow characteristics, which is especially important for precision parts and thin-wall products. For materials with narrow processing windows, such as PMMA, PET, and high-temperature nylon, high-precision thermocouples can effectively avoid viscosity fluctuations caused by temperature drift.
In multi-nozzle systems, consistent performance among all thermocouples ensures balanced viscosity across every cavity, avoiding inconsistent part weight or size. Without reliable temperature control, melt viscosity becomes unpredictable, resulting in high scrap rates and unstable production efficiency.
