Common faults of vacuum atmosphere muffle furnace
09-12-2025 Author: KJ technology
The common faults of vacuum atmosphere muffle furnace can be summarized into the following categories, with corresponding manifestations and solutions:
1. Temperature control malfunction
The temperature cannot reach the set value
Phenomenon: The actual temperature is much lower than the set temperature, or the heating rate is extremely slow.
Reason:
Heating element aging or open circuit (such as silicon carbide rod, broken resistance wire).
The power supply voltage is unstable or the fuse is blown.
Poor sealing of the furnace leads to heat loss (such as aging of sealing strips and failure to close the furnace door tightly).
Solution:
Use a multimeter to test the resistance value of the heating element. If it exceeds the standard, replace it.
Check the power supply and fuses to ensure stable voltage (e.g. 220V/380V).
Replace the sealing strip, clean the residue at the furnace mouth, and ensure that the furnace door is tightly closed.
Large temperature fluctuations or overshoot
Phenomenon: The temperature display value frequently fluctuates or cannot fall back after exceeding the set value.
Reason:
Thermocouple failure (such as oxidation, offset, or compensation wire damage).
Abnormal temperature control module (such as improper PID parameter settings, controller failure).
Solid state relay (SSR) failure leads to unstable output power.
Solution:
Regularly calibrate thermocouples to ensure their installation position is correct (avoiding areas with direct airflow).
Check the control panel parameter settings and restart the device or restore factory settings if necessary.
Check the conductivity of SSR and replace it with the same model of accessory if it is damaged.
2. Vacuum system malfunction
Insufficient vacuum degree or inability to evacuate
Phenomenon: The vacuum pump is running but the pressure gauge reading does not meet the process requirements (such as<10 ⁻ ² Pa).
Reason:
Vacuum pump malfunction (such as oil contamination, rotor wear).
Seal damage (such as O-ring aging, flange compression deformation).
Pipeline or valve leakage (such as cracking of observation window sealant, failure of dynamic sealing of valve stem).
Solution:
Clean or replace the vacuum pump oil, and check the wear of the rotary blades.
Replace high-temperature resistant seals and repair joints.
Use a helium mass spectrometer leak detector to locate small leak points, perform segmented leak detection, and repair.
Unstable vacuum degree
Phenomenon: The pressure gauge reading fluctuates greatly, and the pressure quickly rises during the holding period.
Reason:
Vacuum pump performance degradation (such as oil mist filter blockage causing a decrease in pumping speed).
Gas release from materials inside the furnace (such as insulation layers and workpieces releasing gas at high temperatures).
Solution:
Replace the oil mist filter of the vacuum pump, clean or replace the pump body.
Pre firing treatment: Keep the material at a low temperature range (such as 300 ℃) for a long time to fully release air.
3. Electrical and control system malfunction
The device cannot start or suddenly shuts down
Phenomenon: No response after pressing the start button, or automatic shutdown and display of error codes (such as E1, E2) during operation.
Reason:
The power supply is not connected or the circuit is loose.
Overtemperature protection triggered (such as poor heat dissipation, blocked ventilation openings).
Program parameter error (such as setting the heating rate too fast).
Solution:
Check the power supply and wiring connections to ensure stable socket voltage.
Clean the heat dissipation port or repair the ventilation system, and reduce the heating rate after restarting.
Check the temperature and time settings in the program to avoid sudden and significant temperature increases.
Display abnormality or communication interruption
Phenomenon: No display on the screen, garbled text, or data transmission failure with the controller.
Reason:
Power board malfunction (such as capacitor damage, poor contact).
The screen cable is loose or the system crashes.
Loose interfaces such as the nine pin serial port and aviation plug.
Solution:
Check the power supply of the equipment and eliminate power board faults.
After power failure, reconnect the display cable and press and hold the reset button to restart the device.
Re plug and unplug the interface, and check the reliability of the circuit connection.
4. Mechanical structural faults
The furnace door is stuck or unable to close
Phenomenon: The furnace door switch is not smooth, or the device prompts "furnace door not closed" but is actually closed.
Reason:
The hinge is deformed and obstructed by foreign objects on the track.
Door magnetic switch malfunction (such as decreased sensor sensitivity).
Solution:
Clean up foreign objects on the track and apply high-temperature resistant grease.
Test the door magnetic sensor, clean the dust in the sensing area or replace the sensor.
Mechanical abnormal noise
Phenomenon: Abnormal noise is emitted during operation.
Reason:
Fan bearings are worn or mechanical components are loose.
Solution:
Tighten loose parts, lubricate or replace fan bearings.
5. Other faults
transistor leakage
Phenomenon: The equipment casing is electrified or tripped.
Reason: Insulation damage (such as heating element leakage, power cord damage).
Solution: Check the insulation condition, repair or replace damaged parts, and tighten the wiring terminals.
Overheating of the shell
Phenomenon: Abnormal increase in temperature of the furnace shell.
Reason: Failure of insulation material (such as aging or cracking of insulation layer).
Solution: Replace the insulation material to ensure the insulation performance of the furnace.
