Obvious seasonal temperature alternation brings continuous external environment changes to injection molding workshops, which will subtly affect the working stability and temperature measurement precision of hot runner thermocouples, and easily cause fluctuating product qualification rate without timely adjustment.
In cold winter seasons, the overall indoor ambient temperature drops sharply, and the heat dissipation speed of hot runner manifolds and nozzles is significantly accelerated. A large amount of internal heat is quickly lost to the surrounding low-temperature air. Thermocouples installed inside hot runners will sense accelerated heat loss, leading to the actual feedback temperature lower than the stable state in constant temperature environment. The temperature controller will automatically increase heating power to compensate heat loss, which is easy to cause local overheating inside partial flow channels invisibly, resulting in plastic material yellowing and slight decomposition problems. At the same time, low temperature will increase the hardness of thermocouple connecting wires, making them more prone to brittle fracture during frequent mold opening and closing movements.
In hot summer seasons, high temperature and stuffy workshop environment slow down the natural heat dissipation of hot runner equipment. The external high-temperature thermal radiation continuously acts on thermocouple installation positions, making the displayed temperature value higher than the real melt temperature inside runners. The system will automatically reduce heating output, which leads to insufficient melt temperature, poor fluidity, and further triggers molding defects such as welding lines, shrinkage depressions and incomplete filling. In addition, summer high temperature accelerates the aging speed of thermocouple wire insulating layers, increasing the hidden danger of line leakage.
In the transition seasons of spring and autumn, the large temperature difference between day and night causes repeated cold and heat alternation of hot runner systems and matched thermocouples, easily loosening wiring terminals and causing unstable signal contact. Enterprises need to formulate targeted seasonal adjustment schemes, properly adjust hot runner preset temperature parameters according to ambient temperature changes, increase the frequency of thermocouple data calibration, strengthen wire protection and heat preservation measures, so as to offset the negative impact of seasonal climate changes and keep temperature control always in the best stable state.
