I. Preparation and Self-Test Before Calibration
Power on the hot runner signal generator and allow it to warm up for at least 30 minutes to allow the internal crystal oscillator and analog circuitry to reach thermal stability, eliminating initial deviations caused by temperature drift.
Enter the device's "System Settings" menu and perform a system self-test to confirm that all channels have no hardware errors and the device is functioning normally.
Disable all AM, FM, PM, and other modulation functions, and uniformly select a standard sine wave/DC signal as the output waveform to avoid interference from additional signals during the calibration process.
Prepare a process signal calibrator with an accuracy class ≥ ±0.01%, a high-precision frequency counter, and a digital oscilloscope with a bandwidth ≥ 100MHz as calibration reference equipment.
II. Frequency Reference Accuracy Calibration
Set the signal generator output frequency to a typical value of 10MHz and use the high-precision frequency counter to measure the actual output frequency.
If the measured value deviation exceeds ±1ppm, enter the "Frequency Calibration" menu and adjust the "Frequency Correction Factor" until the deviation is zero.
Repeat the above steps, covering the full frequency range (1μHz to 200MHz), focusing on calibrating the 10kHz, 1MHz, 10MHz, and 100MHz frequency bands commonly used for hot runner calibration to ensure clock reference accuracy meets standards.
III. Output Amplitude Accuracy Calibration
Set the output amplitude to 1Vpp (peak-to-peak value) and measure the actual output amplitude using an oscilloscope or high-precision multimeter.
If the deviation exceeds ±1%, adjust the "Gain Correction Value" through the "Amplitude Calibration" menu to eliminate amplitude output error.
Repeat the above steps, covering the 10mVpp, 100mVpp, 10Vpp, and 20Vpp amplitude ranges commonly used for hot runner calibration. When calibrating high amplitude, enable the oscilloscope's high-impedance input mode (≥1MΩ) to avoid load effects introducing deviations.
IV. Waveform Distortion Calibration
Output a 1kHz sine wave and use the oscilloscope's THD (Total Harmonic Distortion) measurement function to check the waveform distortion.
If the THD exceeds -60dBc, adjust the signal generator's "waveform optimization" parameters, such as filter bandwidth and waveform smoothing coefficient, to reduce waveform distortion.
For waveform distortion caused by capacitive loads, enable the "pre-distortion compensation" function to reverse-correct the output waveform, ensuring the waveform accuracy meets standards under load.
V. Specific Accuracy Calibration for Thermal Signals
Thermocouple Signal Calibration: Set the signal generator to output millivolt analog signals of commonly used thermocouples such as K-type and J-type. Using the millivolt measurement value of the process calibrator as a benchmark, adjust the thermocouple output correction coefficient to ensure the temperature simulation output accuracy matches the calibration requirements of the hot runner temperature control channel.
Resistor Signal Calibration: Set the signal generator to output resistance analog signals of commonly used resistors such as Pt100 and Cu50. Using the resistance measurement value of the process calibrator as a benchmark, adjust the resistor output correction coefficient to ensure the resistance analog output deviation is ≤ ±0.05%FS.
VI. Post-Calibration Verification and Parameter Consolidation
After all calibrations are completed, 10 calibration points are randomly selected across the full measurement range. Output values are measured one by one using a reference device to confirm that the accuracy deviation at all points is within the allowable range.
The device is run continuously for 30 minutes, with output accuracy data collected every 5 minutes to confirm no instability due to time-varying drift.
All calibrated frequency correction coefficients, gain correction values, and thermal signal correction coefficients are saved to the device's non-volatile memory. These parameters will not be lost after a power outage and restart.
All parameter values from this calibration are recorded, generating a calibration file to provide a comparison benchmark for subsequent periodic recalibrations.
Professional calibration is conducted annually by a third-party organization with CNAS accreditation to obtain an authoritative calibration certificate, ensuring traceability of measurement values.
