Standard Process for Regular Calibration of Hot Runner Thermocouples

In addition to being a crucial way to remove accumulated temperature drift errors, stabilize product batch quality, and lower the defective product rate, routine precision calibration is required to maintain the long-term accurate temperature measurement performance of hot runner thermocouples. Accurate temperature benchmarks for injection molding production can be obtained by developing and rigorously implementing unified standard calibration procedures that guaranty the calibration data is accurate, efficient, and consistent.

Enough preparation must be done prior to the official calibration work. To prevent residual high temperatures from influencing the calibration result, first set up a reasonable production shutdown period, halt all hot runner heating operations, and allow the entire hot runner system and thermocouples to cool to a stable room temperature. Second, arrange each thermocouple in each temperature zone individually, clearly identify the installation locations and matching serial numbers, and note the daily use time and previous defect records for further data comparison. To make sure that all testing instruments are within the legitimate verification period, prepare high-precision infrared temperature measurement equipment, professional constant temperature calibration equipment, and standard qualified reference thermocouples in the interim.

Zero-point correction at room temperature is the first step in the formal calibration stage. To unify the initial temperature measurement benchmark, place all thermocouples in the same stable room temperature environment, connect them one at a time to the unified temperature control terminal, record each thermocouple's displayed temperature value, compare it to the actual ambient temperature measured by high-precision instruments, and adjust each product's zero-point deviation with offset errors.

Segmented high-temperature simulation calibration is the second stage. To replicate the typical working temperature portions of hot runners, such as the low-temperature preheating section, the medium-temperature stable molding section, and the high-temperature limit working section, set the constant temperature equipment. The thermocouples to be tested and the standard reference thermocouples should be placed in the same constant temperature space at the same time. The temperature feedback data of each product should be recorded in separate temperature sections. Each thermocouple's temperature measurement error value should be calculated, and the products should be classified and screened based on the error range.

After calibration, the third step is classified disposal. To finish data correction and keep using thermocouples with minor faults within the permitted standard range, enter the compensation value into the matching temperature control controller. Mark products as aging unqualified products, remove them consistently from the mold and replace them with new qualified thermocouples, and forbid the use of out-of-precision accessories in formal production if their drift errors and reduced sensing sensitivity exceed the standard limit.

Organize staff to organize calibration data reports, file, and save them for future inquiry and process reference once all calibration work is finished. It is explicitly stated in daily production management that production lines with difficult working conditions, including filled plastics and recycled materials, abbreviate the calibration cycle to half a month, while typical production lines must finish a full range of precision calibration each month. Strict adherence to defined calibration procedures can consistently maintain thermocouple temperature measurement states within the optimal precision range, provide a strong basis for fine-tuning the injection molding process, and gradually increase the total production benefit.333