Directly installing uncalibrated spare thermocouple as emergency replacement on ongoing precision automotive and medical hot runner production line is a prevalent irregular operation in many small molding workshops supporting YUDO imported hot runner equipment, which brings instantaneous temperature out-of-control risk and intermittent batch defective product loss. Every thermocouple has inherent slight individual deviation range formed during production processing; uncalibrated spare parts possess unknown fixed offset value, after connecting into original calibrated control channel, original matching parameter set by controller cannot compensate new sensor's inherent error, leading local hot runner actual temperature deviate from set target value immediately. For medical transparent plastic hot runner with forming tolerance within ±1℃, even small uncalibrated offset easily triggers gate stringing, internal bubble and dimensional out-of-spec finished product waste.
In addition to static fixed deviation, inferior uncalibrated thermocouple with unstable internal structure generates progressive drift after short-term high-temperature operation, making production parameter adjusted based on original qualified sensor invalid day by day and gradually worsening finished product consistency. Though pre-calibration before installation takes short debugging time and delays production startup temporarily, it avoids far larger economic loss caused by unexpected batch scrapping after formal mass production.
Standard workshop management requires all spare thermocouple used for precision hot runner pass single-point pre-calibration with dry-block equipment before on-site installation; only ordinary low-demand commodity hot runner with wide forming temperature window can allow temporary uncalibrated installation with subsequent parameter revision within same shift to reduce potential quality risk to minimum.
