Could you provide detailed steps for calibrating Husky hot runner sensors?

Based on your past experience in focusing on Husky hot runner K-type thermocouple calibration, sensor verification after heater leakage repair, hot runner full lifecycle maintenance, and your attempt to build a low-cost online calibration system using Python + LabVIEW, the following are complete and detailed operation steps for calibrating Husky hot runner sensors suitable for 320℃ high-temperature, high-load precision injection molding:

 

I. Preparatory steps before calibrating

Tools and Qualification Confirmation Preparation: CNAS-calibrated multi-channel high-precision temperature monitoring equipment, 500V digital megohmmeter, 0.8N·m torque screwdriver, high temperature thermal lubricant, high temperature resistant polyimide tape, heat insulating gloves

Ensure that the calibration staff are competent to operate the hot runner temperature control system. Pre-Access The calibration log for this Husky hot runner system is available here. Check the channel numbers and the temperature measurement sites of all sensors.

Equipment Pre-Check: Before the temperature measurement signal, power down the high power start/stop equipment around the hot runner to minimize grounding loop interference.

Make sure the Husky temperature controller is free of any anomalous alerts such as heater overcurrent, sensor open circuit, etc. Make sure the equipment is in a proper operational condition to heat up.

Peak Pre-heating: During non-production breaks, heat hot runner from room temperature to 280°C and hold. Preheat 30 minutes before calibration at 320°C and maintain for 2 hours until the total temperature of the runner is completely uniform and steady.

 

II. Sensor Pre-Calibration Procedures:

Appearance and Mechanical Inspection. Check each channel for: Thermocouple probes for bending Green corrosion or wear through the armor layer Oxidation or burning of the connector pins Make sure the probe is pushed all the way to the bottom of the detecting hole with no gaps.

Use a torque screwdriver to tighten all the sensor fastening screws to 0.8 N·m. This prevents the probe from becoming loose or displaced.

Insulation Test :** Using a 500V digital mega ohmmeter, test the insulation resistance between the thermocouple core wire and the armor layer and hot runner shell of each channel. An insulating resistance of > 5 MΩ at room temperature is qualified.

The hot runner was maintained at 320℃ for 2 hours and the high temperature insulation resistance was retested. The insulation resistance was >=0.1MΩ, which means there was no risk of insulation failure at high temperatures.

Basic Signal Verification: The thermocouple circuit was verified channel by channel using a multimeter in the millivolt range to verify continuity and no open circuits. The difference between the room-temperature output thermoelectric potential and the theoretical value on the K type thermocouple standard calibration table was <0.05mV.

 

III. On-Site Data Acquisition Procedures

Standard Probe Fixing: The temperature probe of the temperature monitoring instrument was firmly attached to the surface of the corresponding hot runner temperature measurement point with high-temperature-resistant polyimide tape, with the probe and the metal surface of the runner in full contact without gaps.

The probe temperature was let to synchronize totally with the runner temperature throughout 15 min after fixing all the standard probes for all the channels.

Parallel Data Acquisition The multi-channel temperature monitoring device was turned on, and data was acquired one set per minute. The instrument was continually and automatically acquiring 10 sets of synchronous temperature measurement data of all channels.

Automatically and synchronously sample the sensor temperature data of the controller with PTP industrial communication to directly connect with the Husky temperature controller using a prewritten python automated sampling script without human recording.

Data validity screening: Exclude aberrant data jumps generated by equipment start-up and shutdown interference during the acquisition process, and maintain 10 sets of continuous and steady valid temperature measurement data. Determine the mean deviation of the standard value and the value of the temperature measurement of the sensor of each channel.

 

IV. Steps for Parameter Modification of Husky Temperature Controller

Calibration Menu Access: Input the administrator password on the operation panel of the Husky temperature controller and open the "Sensor Calibration" menu to choose the matching channel to be calibrated.

The cold-junction compensation should not introduce additional errors. Make sure that the cold-junction compensation reference value for the current channel is the same as the measured room temperature value.

Compensation parameters setting: In the temperature compensation parameter input field of the calibration offset of the associated channel, input the inverse of the estimated average deviation for each channel.

For systems with 8 channels or less, all channels' compensation parameters can be imported in one go straight. For systems with 16 or more channels, please make sure that the parameters for each channel agree one to one with the acquired data so that channels are not misaligned.

Save and Implementation of Parameters Enter all channel compensation parameters then click "Save and Implementation". The temperature controller will automatically load the new calibration values, reset the cold junction correction and update the sensor temperature data immediately.

 

V. Post-Calibration Stability Check Steps

Accuracy Re-verification: 30 minutes after the parameters take effect, synchronously collect 5 sets of temperature data again to validate that the temperature variation of all channel sensors is ≤±1℃, without jumps or drifts.

Increase and lower the set temperature manually by 10°C three times respectively, examine the process of PID adjustment, and validate that the overshoot of temperature is ≤ 2°C and return to the set value within 3 min.

Long-Term Stability Verification: Run continuously for 1 hour at the selected temperature, monitor the temperature data of all channels during the operation, and check that the temperature fluctuation range is ≤±0.5℃, without irregular jumps.

Simulate the start and stop of neighboring high power equipment to validate that the sensor temperature data is not subject to instantaneous jumps and is not influenced by grounding loop interference.

Trial production final acceptance: perform low-speed trial production, produce 20 sets of items constantly. Monitor sensor temperature data and dynamic variations of heater current in the whole process without overcurrent alarm and signal interruption.

Check whether the appearance and dimensional accuracy of the trial-produced items satisfy the requirements, whether there is a lack of glue, uneven stress and other temperature anomalies, and whether the process stability satisfies the requirements in all aspects.

 

VI. Calibration Closed Loop Archiving Procedure:

Automatic Data Upload: All the original data acquired during this calibration, compensation parameters and verification findings are automatically and synchronously uploaded to the existing MES system to generate a calibration report with CNAS traceability.

Auto update the sensor life maintenance log for this Husky hot runner system with calibration time, deviation value, and next calibration cycle for each channel.

Dynamic Cycle Adjustment: When there are 3 consecutive calibration variations < ±0.5℃ for a sensor, the calibration cycle will be automatically prolonged from 3 months to 6 months.

Sensors having calibration deviation over ±2℃ will be identified as key monitoring objectives, and the calibration cycle will be temporarily shortened to 2 weeks in the next period. The original cycle will be progressively recovered when two consecutive calibration failures are stable.