Common faults and solutions of high-temperature vacuum brazing furnace

03-24-2025       Author: KJ technology

During long-term use, some common malfunctions may occur in high-temperature vacuum brazing furnaces. Here are some common fault phenomena, causes, and corresponding solutions:

1. Temperature control malfunction

Fault phenomenon:

The temperature control is inaccurate and cannot reach the set value.

Reason for occurrence:

Thermocouple wire breakage or aging.

Temperature control instrument malfunction.

resolvent:

Check if the thermocouple is intact. If there are any broken wires or aging, replace the thermocouple with a new one in a timely manner.

Perform maintenance according to the instructions of the temperature control instrument and replace it with a new one if necessary.

2. The vacuum degree does not meet the technical standards or the evacuation time is too long

Fault phenomenon:

The vacuum brazing furnace cannot reach the predetermined vacuum degree, or the evacuation time is significantly prolonged.

Reason for occurrence:

Vacuum pump malfunction, such as pump oil contamination, pump body wear, etc.

Vacuum system leakage, such as furnace body leakage, vacuum pipeline connection leakage, etc.

The resistance gauge and ionization gauge of the vacuum gauge are damaged.

resolvent:

Check the working status of the vacuum pump, such as whether the pump oil is clean, whether the pump body is worn, etc. If necessary, replace the pump oil or repair the pump body.

Check the sealing of the vacuum system, with a focus on areas such as the furnace body and vacuum pipeline connections that are prone to leakage. If there is any leakage, replace the sealing ring or perform welding repair in a timely manner.

Replace the damaged vacuum gauge gauge tube.

3. The heating power cannot reach the rated value

Fault phenomenon:

During the heating process of the vacuum brazing furnace, the heating power is significantly lower than the rated value.

Reason for occurrence:

Magnetic regulator malfunction.

The graphite heating tube is contaminated or aged, resulting in 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 contaminated or aged graphite heating tubes.

Check the resistivity of the new graphite tube to ensure it matches the regulator.

4. Inaccurate thermocouple

Fault phenomenon:

There is a deviation between the temperature measured by the thermocouple and the actual temperature.

Reason for occurrence:

The installation position of the thermocouple is incorrect.

The thermocouple model and specifications do not meet the requirements.

Dust accumulation or looseness at the thermocouple terminal.

resolvent:

Adjust the installation position of the thermocouple again to ensure that it is in the correct measurement position.

Replace the thermocouple that meets the requirements.

Clean the accumulated dust at the thermocouple terminal and check if the wiring is loose to ensure good contact.

5. Vacuum valve switch malfunction

Fault phenomenon:

The vacuum valve cannot be opened or closed normally.

Reason for occurrence:

The compressed air pressure is insufficient.

Electromagnetic valve malfunction, such as vibration causing relative movement between the electromagnet and the housing.

resolvent:

Check the compressed air pressure to ensure it is not lower than the specified value (usually 0.5MPa).

Repair the solenoid valve, replace it with a new one if necessary, and check for any vibration source. If so, take measures to eliminate the vibration.

6. Mechanical pump malfunction

Fault phenomenon:

Mechanical pumps cannot start or operate flexibly.

Reason for occurrence:

The position of the motor starter switch is incorrect or the overload protection device is triggered.

Motor wiring error or motor damage.

Wear or oil contamination of the pump body.

resolvent:

Check the position of the motor starter switch and overload protection device to ensure that they are working properly.

Check if the motor wiring is correct, and if there are any errors, rewire it; If the motor is damaged, replace it with a new one.

Check the wear of the pump body and repair it if necessary; Replace the pump oil with a new one and ensure that the pump body is clean.

7. Unstable vacuum degree

Fault phenomenon:

During the heating process, the vacuum degree of the vacuum brazing furnace fluctuates.

Reason for occurrence:

The working state of the vacuum pump is unstable.

There is a leakage phenomenon in the vacuum system.

resolvent:

Check the working status of the vacuum pump, such as whether the pump oil is clean, whether the pump body is worn, etc., and repair or replace it if necessary.

Check the sealing of the vacuum system, with a focus on areas such as the furnace body and vacuum pipeline connections that are prone to leakage. If there is any leakage, replace the sealing ring or perform welding repair in a timely manner.

8. Serious equipment leakage

Fault phenomenon:

The vacuum brazing furnace experiences significant air leakage during the vacuuming process.

Reason for occurrence:

Leakage at the seal of the vacuum pump.

The vacuum pipeline connection is not tightly sealed.

The sealing components of the furnace body are aging or damaged.

resolvent:

Check the sealing area of the vacuum pump. If there is any leakage, replace it with a new sealing ring.

Check the connection of the vacuum pipeline. If there is any leakage, tighten the connection again or replace it with a new sealing ring.

Check the sealing components of the furnace body, and replace them with new ones if they are aged or damaged.

9. Other common faults and solutions

Fault phenomenon:

Dealing with issues such as uneven surface of parts, burnt thermocouples, and low insulation resistance.

Causes and solutions:

Dealing with the surface of the parts not being shiny:

Reason for occurrence: impure cooling gas or low vacuum degree.

Solution: Ensure that the purity of the cooling gas (such as argon) meets the requirements (usually above 99.9996%), and check the vacuum system and cooling system of the vacuum brazing furnace to ensure that they are working properly.

Thermocouple burnt out:

Cause: The thermocouple collides with the carbon felt or the thermocouple is not sealed.

Solution: Eliminate the collision between the vacuum brazing furnace heater and the thermocouple, and check the sealing ring of the thermocouple to ensure good sealing.

Low insulation resistance:

Cause: There are carbon fibers or other conductive substances around the electrode.

Solution: Remove flying copper, oven treatment, clean carbon fiber and other conductive substances to improve insulation resistance.

Summarize

During long-term use, high-temperature vacuum brazing furnaces may experience various malfunctions. In order to ensure the normal operation of the equipment and extend its service life, operators should regularly maintain and inspect the equipment, timely discover and deal with potential faults and hidden dangers. At the same time, corresponding solutions should be taken based on the cause of the malfunction to ensure that the equipment can resume normal operation.