The temperature of the high-temperature vacuum atmosphere tube furnace cannot rise

The inability to increase the temperature of a high-temperature vacuum atmosphere tube furnace may be caused by various factors such as power supply, heating elements, control system, vacuum and atmosphere system, furnace structure or operating settings. The following are specific reasons and corresponding troubleshooting and solutions:

1. Power supply and power supply issues
Insufficient power supply voltage
Phenomenon: Heating power below rated value, slow or stagnant temperature rise.
Troubleshooting method: Measure the input voltage with a multimeter to confirm if it meets the equipment requirements.
Solution: Contact an electrician to check the power supply line and adjust the output of the transformer or voltage regulator.
Poor contact of the circuit
Phenomenon: Local overheating or current fluctuations, unstable temperature curve.
Troubleshooting method: Check if the power cord and heating rod connections are loose or oxidized.
Solution: Tighten the wiring terminals, remove the oxide layer, and replace the aging circuit if necessary.

2. Heating element malfunction
Heating rod damaged
Phenomenon: There is no heating in a certain heating zone, and the resistance value is abnormal (such as open circuit or short circuit).
Troubleshooting method: Use a megohmmeter to measure the resistance of the heating rod and compare it with the standard value (such as a silicon molybdenum rod with a room temperature resistance of about 10-20 Ω).
Solution: Replace the damaged heating rod, pay attention to model matching (such as U-shaped, W-shaped).
Heating rod aging
Phenomenon: The heating rate slows down, and the maximum temperature is lower than the set value.
Troubleshooting method: Record the historical temperature rise curve and compare it with the current data.
Solution: Regularly replace aging heating rods (recommended to replace every 2-3 years).
Uneven distribution of heating rods
Phenomenon: The temperature field inside the furnace is uneven, and local heating is limited.
Troubleshooting method: Use an infrared thermometer to scan the furnace and locate the low-temperature zone.
Solution: Adjust the spacing between heating rods or add auxiliary heating zones.

3. Abnormal control system
Temperature control instrument malfunction
Phenomenon: There is a large deviation between the displayed temperature and the actual temperature, or the control signal cannot be output.
Troubleshooting method: Check the instrument parameter settings (such as PID values) and test the output with analog signals.
Solution: Calibrate or replace the temperature control instrument.
Thermocouple damaged
Phenomenon: Abnormal temperature display (such as fixed value or garbled code), actual temperature does not reach the set value.
Troubleshooting method: Use a multimeter to measure the output voltage of the thermocouple and compare it with a standard calibration table.
Solution: Replace the thermocouple with the same model (such as N-type, S-type), paying attention to the insertion depth.
Solid state relay (SSR) malfunction
Phenomenon: The heating rod works intermittently with large temperature fluctuations.
Troubleshooting method: Use an oscilloscope to detect SSR input/output signals, or measure the input terminal voltage.
Solution: Replace the SSR module.

4. The influence of vacuum and atmosphere systems
Insufficient vacuum degree
Phenomenon: The heat conduction of the gas inside the furnace is enhanced, the heat dissipation is fast, and the temperature rise is slow.
Troubleshooting method: Use a vacuum gauge to check the pressure and confirm whether it meets the process requirements.
Solution: Check the vacuum pump, valves, and sealing rings, and repair any leaks (such as flange connections).
Excessive gas flow rate in the atmosphere
Phenomenon: Gas convection takes away heat, causing temperature stagnation.
Troubleshooting method: Measure gas flow rate with a flow meter and compare process parameters.
Solution: Adjust the gas flow rate to a reasonable range.
Insufficient gas purity
Phenomenon: Impurity gases participate in the reaction, consuming heat or generating by-products.
Troubleshooting method: Check the purity of the gas and confirm the quality of the gas source.
Solution: Replace high-purity gas or add gas purification equipment.

5. Furnace structure and design issues
Aging of insulation materials
Phenomenon: The outer wall temperature of the furnace is too high, resulting in severe heat loss.
Troubleshooting method: Check whether the insulation layer (such as mullite fiber, alumina cotton) has cracked or fallen off.
Solution: Replace the insulation material and refill the gaps in the furnace.
The furnace size is too large
Phenomenon: Insufficient heating power and poor temperature uniformity.
Troubleshooting method: Calculate the ratio of furnace volume to heating power.
Solution: Upgrade the heating system or optimize the furnace design (such as adding insulation screens).
The furnace door is not tightly sealed
Phenomenon: Cold air infiltrates, causing a decrease in temperature.
Troubleshooting method: Check if the furnace door sealing ring is deformed or damaged.
Solution: Replace the sealing ring or adjust the furnace door clamping device.

6. Operation and setting issues
Heating program error
Phenomenon: The segmented heating rate is set too low, or the insulation time is insufficient.
Troubleshooting method: Check the process curve to confirm the heating rate and target temperature.
Solution: Re edit the heating program and add insulation sections.
Excessive load
Phenomenon: The workpiece absorbs too much heat, resulting in a slow temperature rise.
Troubleshooting method: Calculate the heat capacity of the workpiece (such as mass x specific heat capacity) and compare the heating power.
Solution: Reduce the amount of furnace loading per time or extend the heating time.
Rapid cooling and heating operation
Phenomenon: Excessive thermal stress on the furnace body can cause damage to heating elements or temperature loss of control.
Troubleshooting method: Check the operation records to confirm whether the heating/cooling rate requirements have been violated.
Solution: Strictly follow the process specifications to avoid sudden temperature changes.

7. Comprehensive investigation process
Preliminary inspection: Confirm that the power and gas supply are normal, and the furnace door is tightly closed.
Empty furnace test: Without loading the workpiece, run the heating program and observe the temperature curve.
Segmented investigation:
If the empty furnace is normal, check the workpiece load and placement method;
If the empty furnace is abnormal, check the heating element, temperature control system, and vacuum system.
Data recording: Record fault phenomena and parameter changes to provide a basis for subsequent maintenance.