Many mold maintenance departments save spare part cost by mixing thermocouple from different domestic and imported brands on one set of multi-zone hot runner originally equipped with Husky or YUDO original sensors, inconsistent alloy composition, filling compactness and thermoelectric characteristic among diversified brand products induce uneven inter-channel temperature deviation and disordered hot runner melt balance, bringing continuous hidden quality trouble for mass injection production. Different manufacturers adopt self-formulated thermo-alloy smelting standard according to own technical system, even same nominal K-type thermocouple from two factories exists subtle thermoelectric curve difference; after mixed installation on manifold different partition, identical actual hot runner temperature generates inconsistent feedback potential value, leading controller to output differentiated heating power for adjacent heating zones and creating obvious temperature difference among manifold sub-regions.
Uneven temperature distribution further causes inconsistent melt viscosity inside runner channel, some cavities appear overheating flash while others suffer insufficient filling short shot on same batch molded products, especially prominent on high-precision 32-cavity and above multi-cavity packaging hot runner with strict flow balance requirement. Besides, dissimilar sheath processing craft makes different brand thermocouple vary in heat conduction efficiency and spring preload design; same installation hole produces inconsistent probe contact tightness after mounting, accelerating gradual measuring drift divergence as production cycle accumulates.
Controller internal parameter is calibrated matching original supporting brand thermocouple; mixed different-brand sensors break original calibration benchmark, regular parameter fine-tuning for one brand's product inevitably worsens matching state of other brand sensors on same control channel. Standard workshop management stipulates one complete set of hot runner uniformly adopts thermocouple from single fixed brand; during emergency urgent maintenance temporary replacement, mark mixed channel number clearly and carry out unified full equipment calibration after finishing production order to eliminate mixed matching induced systematic error. Abandoning random mixed-brand matching principle is basic guarantee to stabilize multi-cavity hot runner forming consistency and lower finished product defective rate effectively.
