Common faults and solutions of vacuum brazing furnace
03-21-2025 Author: KJ technology
Vacuum brazing furnaces may encounter various faults during use. The following are some common fault phenomena, possible causes, and corresponding solutions:
1. Temperature control malfunction
Fault phenomenon:
The temperature display of the vacuum brazing furnace is inaccurate or cannot be adjusted.
Possible reasons:
Thermocouple wire breakage or damage.
Temperature control instrument malfunction.
resolvent:
Replace the thermocouple with a new one.
Repair or replace the temperature control instrument according to the instruction manual.
2. Insufficient vacuum degree or too long evacuation time
Fault phenomenon:
The vacuum brazing furnace cannot reach the maximum vacuum degree or the evacuation time is too long.
Possible reasons:
Vacuum brazing furnace vacuum system failure, such as decreased performance of vacuum pump, valve leakage, etc.
Furnace leakage, such as aging of sealing rings, cracking of welds, etc.
The resistance gauge and ionization gauge of the vacuum gauge are damaged.
resolvent:
Check and repair the vacuum pump to ensure its good performance.
Check the sealing condition of the furnace body, replace the aging sealing ring, and repair the weld seam.
Replace the damaged vacuum gauge gauge tube.
3. The heating power cannot reach the rated value
Fault phenomenon:
The heating power of the vacuum brazing furnace is insufficient, and the temperature rise is slow.
Possible reasons:
Magnetic regulator malfunction.
Graphite heating tube contamination leads to an increase in resistance value.
The resistivity of the new graphite tube does not match the voltage regulator.
resolvent:
Inspect the magnetic voltage regulator to ensure its proper functioning.
Replace the contaminated graphite heating tube.
Check and adjust the resistivity of the graphite tube, or replace the graphite tube that matches the regulator.
4. Thermocouple malfunction
Fault phenomenon:
The thermocouple reading is inaccurate or displays abnormally.
Possible reasons:
Thermocouple hot electrode short circuit or open circuit.
Dust accumulation or looseness at the thermocouple terminal.
Compensating wires are connected in reverse or incompatible with thermoelectric dipoles.
resolvent:
Identify the cause of the short circuit or open circuit, repair or replace the thermocouple.
Clean the accumulated dust at the thermocouple terminal and tighten the terminal.
Reconnect the compensation wire to ensure its polarity matches that of the thermocouple, and use it together.
5. Vacuum valve switch malfunction
Fault phenomenon:
The vacuum valve cannot be opened or closed normally.
Possible reasons:
The compressed air pressure is insufficient.
Electromagnetic valve malfunction, such as vibration causing relative movement between the electromagnet and the housing.
resolvent:
Ensure that the air pressure is not less than the specified value (such as 0.5MPa).
Inspect the solenoid valve and, if necessary, add rubber pads to tighten it.
6. Mechanical pump malfunction
Fault phenomenon:
Mechanical pumps cannot start or operate flexibly, resulting in low pumping efficiency.
Possible reasons:
The position of the motor starter switch is incorrect or the overload protection device is malfunctioning.
The three-phase wiring of the motor is incorrect.
Pump oil pollution, insufficient or too thin.
Shaft seal oil leakage or bearing wear.
resolvent:
Check the position of the motor starter switch and overload protection device to ensure that they are working properly.
Replace the incorrect wiring in the three-phase motor.
Clean the vacuum pump, replace it with new vacuum pump oil, and ensure that the oil level is moderate.
Replace the shaft seal or bearing.
7. Leakage issue
Fault phenomenon:
The vacuum degree of the vacuum brazing furnace drops too quickly or cannot reach the predetermined vacuum degree during the evacuation process.
Possible reasons:
The furnace door sealing ring, electrode sealing ring, thermocouple sealing ring, etc. are aging or damaged.
Cracking of furnace body welds or leakage of connecting flanges and pipelines.
The heat exchanger inside the vacuum brazing furnace is leaking water.
resolvent:
Regularly inspect and replace aging sealing rings.
Leak detection and repair of furnace body welds to ensure good sealing of connecting flanges and pipelines.
Check and repair the water leakage problem of the heat exchanger inside the vacuum brazing furnace.
8. Other common faults and solutions
Dealing with the surface of the parts not being shiny:
Possible reasons: impure cooling gas or low vacuum degree.
Solution: Ensure that the purity of nitrogen (argon) gas is above 99.9996%, and check the vacuum system and cooling system of the vacuum brazing furnace.
Thermocouple burnt out:
Possible reason: The thermocouple is in contact or not sealed with the carbon felt.
Solution: Eliminate the contact between the vacuum brazing furnace heater and the thermocouple, and check the sealing ring of the thermocouple.
Low insulation resistance:
Possible reason: There are impurities such as carbon fibers around the electrode.
Solution: Remove flying copper, oven treatment, and clean impurities such as carbon fiber.
9. Daily maintenance and prevention
Regular inspection and maintenance: Regularly inspect and maintain the vacuum brazing furnace, including replacing filters, checking the oil level and temperature of the vacuum pump, cleaning the vacuum pump, etc.
Pay attention to operating procedures: During the operation process, strictly follow the operating procedures to avoid improper operation that may cause equipment failure.
Timely troubleshooting: Once a device malfunction is detected, it should be immediately shut down for inspection, the cause of the malfunction should be identified, and the problem should be promptly resolved.
Through the above methods, common faults encountered during the use of vacuum brazing furnaces can be effectively solved, ensuring the normal operation of equipment and welding quality.
