Common faults of customized experimental rotary tube furnace

The common faults and cause analysis of customized experimental rotary tube furnaces are as follows, which can be quickly identified by system classification:

1. Power and electrical system malfunction
The indicator light is not on or there is no power display
Reason: The fuse is blown, the plug is not properly inserted, and the control circuit fuse is blown.
Performance: There is no response from the device and no display on the instrument after power on.
Solution:
Check if the power plug is loose and replace the blown fuse (matching the rated current);
Use a multimeter to check for a short circuit in the control circuit, and replace the fuse after troubleshooting.
The ammeter has no current, while the voltmeter has voltage
Reason: The heating element (such as silicon carbon rod, silicon molybdenum rod) is broken.
Performance: The voltage is normal but there is no current in the heating circuit, and the furnace does not heat up.
Solution:
Open the furnace door and observe whether there are cracks or fractures on the appearance of the heating element;
Use a multimeter to measure the resistance of the heating element. If it is infinite, it needs to be replaced.

2. Temperature control system malfunction
Abnormal temperature display (no rise, fluctuation or large deviation)
Reason:
Sensor damage or failure (such as thermocouples, Pt100 platinum resistors);
Temperature controller parameter setting error or PID adjustment failure;
The deviation between the temperature measurement point and the layout point (such as the thermocouple not being inserted into the material center).
Performance: Temperature display stagnates, fluctuates more than ± 5 ℃, or does not match the actual temperature.
Solution:
Use a multimeter to detect sensor resistance or voltage signals, and replace damaged sensors;
Reset the temperature controller parameters (such as P=10-20, I=1-5, D=0.5-2);
Adjust the position of the thermocouple to ensure good contact between the temperature measuring point and the material.
Abnormal heating rate (too fast or too slow)
Reason:
Improper setting of heating program (such as insufficient segmented insulation time);
Insufficient power or aging of heating elements;
Poor sealing of the furnace leads to heat loss.
Performance: The heating time to the target temperature far exceeds the preset program.
Solution:
Adjust the heating program according to the material characteristics (such as keeping aluminum hydroxide at 300 ℃ for 2 hours to remove crystal water);
Check the resistance value of the heating element and replace the aging element;
Check if the furnace door seal is damaged, replace the sealing ring, and ensure that the furnace door is tightly closed.

3. Heating system malfunction
Uneven distribution of furnace temperature
Reason:
Uneven distribution or local damage of heating elements;
There is dirt or excessive material accumulation in the furnace.
Performance: The temperature difference between different positions in the furnace exceeds ± 10 ℃.
Solution:
Adjust the position of the heating element to ensure uniform distribution;
Clean the interior of the furnace to remove dirt and oxides;
Reduce the amount of materials and spread them evenly (recommended thickness<50mm).
The temperature cannot reach the set value
Reason:
The set temperature is lower than the actual capacity of the furnace (for example, a furnace with a rated temperature of 1200 ℃ is set to 1300 ℃);
Insufficient heating element power or unstable power supply voltage;
The aging of furnace insulation materials leads to heat loss.
Performance: After the temperature reaches a certain value, it stagnates and cannot continue to rise.
Solution:
Check if the set temperature exceeds the rated value of the furnace;
Use a voltmeter to check if the power supply voltage is stable;
Replace insulation materials (such as alumina fiber, ceramic fiber) or install insulation covers.

4. Mechanical and structural failures
Furnace cracking or deformation
Reason:
Not baked after first use or prolonged disuse (direct high-temperature heating in a cold furnace);
Excessive heating rate leads to thermal stress concentration.
Performance: Cracks or local bulges appear on the inner wall of the furnace.
Solution:
Bake according to the program before first use (such as baking at 120 ℃ for 1 hour, baking at 300 ℃ for 2 hours);
Set a reasonable heating rate (such as ≤ 10 ℃/min) to avoid sudden temperature changes.
The rotating mechanism is stuck or making abnormal noises
Reason:
Rotating bearings lack oil or are damaged;
The accumulation of materials inside the furnace tube hinders rotation.
Performance: The furnace tube does not rotate smoothly or makes friction sounds.
Solution:
Regularly add lubricating oil (such as high-temperature grease) to the rotating bearings;
Clean the materials inside the furnace tube to ensure sufficient space for rotation.

5. Other common faults
Vacuum degree decrease (for vacuum type furnaces)
Reason:
The flange sealing ring is aging or not installed correctly;
Vacuum pump malfunction or pipeline leakage.
Performance: The vacuum degree cannot reach the set value or the holding time is short.
Solution:
Replace the heat-resistant silicone sealing ring and reinstall the flange;
Check the oil level and pipeline connection of the vacuum pump, and repair the leakage point.
Interruption or error during program execution
Reason:
Controller memory failure or program error;
External interference (such as electromagnetic fields) causes signal interruption.
Performance: The temperature controller displays an error code or the program automatically stops.
Solution:
Restart the controller and re-enter the program;
Stay away from electromagnetic interference sources such as high-power motors and frequency converters.