How to calibrate the furnace temperature sensor during the tempering of H13 material

A standard thermocouple comparison method must be used to calibrate the furnace temperature sensor during the tempering of H13 material. To guaranty temperature control accuracy and process stability, regular on-site calibration should be carried out at the operating point of 580℃±5℃ to ensure that the measurement variance is ≤±5℃.

 

1. Core Techniques and Procedures for Calibration

Procedures

Operating Guidelines

Choose Standard Equipment

As a reference, use a high-precision thermometer and a standard platinum-rhodium thermocouple with an accuracy of ±1°C that has been confirmed by metrology.

Establish Temperature Points for Calibration

Conduct multi-point calibration at two endpoints, 550°C and 600°C, which cover regularly utilized temperature ranges, as well as at 580°C, the optimal process temperature.

Place Sensors Synchronously

To ensure constant heating conditions, place the standard thermocouple and the sensor to be calibrated (such as a type K thermocouple) in parallel in the furnace's medium-temperature zone.

After stabilization, compare the readings.

Once the temperature has stabilized for at least half an hour, note the displayed value and the standard value, then compute the deviation.

Modification or Substitution

The temperature control system must be adjusted or the sensor must be changed if the variance is more than ±5°C.

Practical Advice: To prevent the workpiece from absorbing heat and compromising the temperature field's uniformity, calibration should be carried out under empty or light load conditions.

 

2. Management Requirements and the Calibration Cycle

Regular Calibration: Completed every three months;

Instant Calibration for Unusual Circumstances: such as significant variations in hardness, unusual drift in furnace temperature curves, or during equipment repair;

Create Calibration Records: For traceability, note the date of each calibration, standard number, measured variation, and operator;

Labeling: Put calibration labels with the next calibration date on the sensors.

Note: It is advised to reduce the calibration interval to once every six weeks for older furnaces or high-frequency use settings.

 

3. Supplementary Steps to Boost Calibration Efficiency

Multi-point Joint Calibration: To detect local temperature variations, set up several measuring points in the furnace's upper, middle, lower, and corner regions;

TUS Testing: To confirm overall performance in accordance with AMS 2750 requirements, conduct a furnace temperature uniformity test (TUS) following calibration;

Choose Certified Service Providers: Wuhan Heat Treatment Plant and Jingmo Technology, for example, have AMS 2750 and CQI-9 certifications, guaranteeing a more uniform calibration procedure.

"Standard comparison, periodic execution, and data archiving" are safety concepts that guaranty the sensor's dependability at all times.