The temperature of the rapid heating and cooling annealing furnace cannot rise

The temperature of the rapid temperature rise and fall annealing furnace (RTP) cannot reach the set value, which may be caused by various factors such as heating system, temperature control, process parameters, or equipment maintenance. The following is a detailed analysis of the reasons and solutions:

1. Heating system malfunction
Heating element damaged
Phenomenon: Heating tube/filament breakage, abnormal resistance value, or local overheating.
Reason: Long term high-temperature work leads to material aging, or frequent rapid temperature rise and fall causes thermal stress fatigue.
Solution:
Measure the resistance of the heating element with a multimeter and compare it with the nominal value.
Visually inspect the surface of the heating tube for cracks or discoloration, and replace damaged components.
Regularly (e.g. every 500 cycles) carry out preventive replacement.
Insufficient power supply
Phenomenon: Voltage/current below rated value, insufficient heating power.
Reason: Aging of power lines, poor contact, or insufficient transformer capacity.
Solution:
Check if the power cord is damaged and use a clamp gauge to measure the actual current.
Confirm that the output voltage of the transformer matches the equipment requirements.
Add a voltage regulator or upgrade the power system.
Failure of insulation material
Phenomenon: The heat loss in the furnace chamber is too fast, and the temperature rises slowly.
Reason: Aging or detachment of insulation cotton or inadequate sealing of the furnace body.
Solution:
Check whether the sealing strips of the furnace door, observation window and other parts are intact.
Replace high-temperature insulation cotton (such as alumina fiber felt) with a recommended thickness of ≥ 50mm.
Install a reflective screen on the outside of the furnace to reduce radiation and heat dissipation.

2. Temperature control issues
Sensor malfunction
Phenomenon: The temperature display value deviates greatly from the actual value, or the control is unstable.
Reason: Damage, displacement, or calibration failure of thermocouple/infrared thermometer.
Solution:
Use a standard temperature source (such as a dry well furnace) to calibrate the sensor, with an error of<± 1 ℃.
Check if the sensor installation location is close to the heating source or airflow interference area.
Replace aging sensors (such as N-type thermocouples with a lifespan of approximately 2000 hours).
PID parameter imbalance
Phenomenon: Temperature overshoot, oscillation, or delayed response.
Reason: The proportional (P), integral (I), and derivative (D) parameters have not been optimized for device characteristics.
Solution:
Using Ziegler Nichols method for parameter tuning:
Set I=0 and D=0, gradually increase P until the system produces sustained oscillations, and record the critical gain Ku and period Tu.
Set P=0.6Ku, I=Tu/2, D=Tu/8.
Make minor adjustments based on the recommended values in the equipment manual (such as increasing the P-value for rapid temperature rise and fall scenarios).
Control software vulnerabilities
Phenomenon: Abnormal execution of temperature curve or failure of alarm function.
Reason: Old software version, communication protocol conflict, or database error.
Solution:
Upgrade the control software to the latest version.
Check if the communication between the PLC and the upper computer is normal (e.g. Modbus RTU protocol baud rate needs to be consistent).
Backup and reset the control parameter database.

3. Process parameter setting error
The heating rate is too high
Phenomenon: Temperature stagnates or decreases at a certain stage.
Reason: Insufficient heating power or equipment thermal inertia limitation.
Solution:
Reduce the heating rate (such as from 100 ℃/s to 50 ℃/s).
Set the heating curve in segments (such as first raising to 300 ℃ at 30 ℃/s, and then raising to the target temperature at 50 ℃/s).
Target temperature exceeds the limit
Phenomenon: The device alarms and stops heating.
Reason: The set temperature exceeds the rated value of the equipment (e.g. equipment with a nominal temperature of 600 ℃ is set to 700 ℃).
Solution:
Confirm the maximum operating temperature specified in the equipment specifications.
Modify the process parameters to a safe range.
Gas flow interference
Phenomenon: The temperature drops after the introduction of protective gas (such as N ₂).
Reason: Excessive gas flow leads to enhanced convective heat dissipation.
Solution:
Adjust the gas flow rate to the recommended value (such as 5-10 L/min).
Install a preheating device (such as a wrapped heating belt) at the air inlet.

4. Insufficient equipment maintenance
Furnace cavity pollution
Phenomenon: Impurities evaporate and adsorb on the surface of heating elements or sensors, affecting heat transfer.
Reason: Previous process residues or environmental dust entered the furnace chamber.
Solution:
Regularly clean the furnace chamber (such as wiping with a dust-free cloth after every 100 cycles).
Install a high-efficiency filter at the air intake.
Mechanical components stuck
Phenomenon: The furnace door cannot be fully closed or the movement of the sample stage is obstructed.
Reason: Insufficient lubrication of the guide rail or deformation of the transmission mechanism.
Solution:
Regularly apply high-temperature grease (such as molybdenum disulfide based grease).
Check and calibrate the tension of the transmission chain.
Cooling system malfunction
Phenomenon: During the rapid cooling phase, the temperature drops slowly, affecting the heating of the next cycle.
Reason: Insufficient cooling water flow or fan shutdown.
Solution:
Check the cooling water pressure (≥ 0.2 MPa) and temperature (recommended<25 ℃).
Clean the fan filter to ensure that the air volume is ≥ 500 m ³/h.

5. Typical troubleshooting process
Preliminary inspection: Confirm that the power and gas supply are normal, and the equipment has no alarm codes.
Empty load test: Without placing the sample, run the heating program and observe whether the temperature curve meets the standard.
Segmented investigation:
If the no-load condition is normal, check whether the sample size/material affects heat transfer (such as extending the insulation time for large-sized samples).
If there is no load abnormality, check the heating element, sensor, and control parameters.
Data recording: Use a data acquisition instrument to record the actual temperature curve and compare it with the set value to analyze the deviation nodes.
Professional maintenance: If unable to solve the problem on your own, contact the equipment supplier for in-depth diagnosis (such as using an infrared thermal imager to detect furnace temperature distribution).

6. Preventive maintenance recommendations
Daily inspection: furnace chamber cleanliness, gas flow rate, cooling water pressure.
Weekly maintenance: calibrate temperature sensors and lubricate mechanical components.
Monthly maintenance: replace insulation materials and check the resistance of heating elements.
Annual overhaul: Conduct comprehensive equipment performance testing and update control software.
By systematically investigating heating systems, temperature control, process parameters, and equipment maintenance, the problem of RTP temperature not rising can be quickly located and solved, ensuring stable operation of equipment in high-precision process scenarios such as photovoltaic manufacturing.