Common faults and solutions of box type resistance furnaces

Box type resistance furnaces may encounter various faults during use. Here are some common faults and their solutions:

1. Heating fault
Heating up too slowly or unable to reach working temperature
Possible reasons: low grid voltage, unbalanced three-phase current, open circuit or phase loss of electric heating elements, resistance value of electric heating elements not meeting requirements, reduced power of electric heating elements, short circuit phenomenon of electric heating elements, excessive furnace loading, deterioration of insulation screen or lining performance, incorrect connection method of electric heating elements, low output voltage of furnace transformer, low output power of power regulator, and malfunction of temperature control device.
Solution: Check the grid voltage, measure the resistance of the electric heating element, check the fault point of the electric heating element, replace the electric heating element, eliminate the short circuit point, reduce the loading amount, replace the insulation layer, correctly connect the electric heating element, check the furnace transformer, check or adjust the power regulator, and eliminate control device faults.
The power supply voltage is normal, but the operating voltage of the electric furnace is low
Possible reasons: The voltage drop of the power supply line is too large or the sockets and control switches have poor contact.
Solution: Adjust or replace the power supply line to ensure good contact.

2. Sealing malfunction
Poor sealing performance
Possible reasons: aging of furnace cover sealing ring, air leakage in furnace body, poor sealing of vacuum pipeline valves, poor sealing at electrodes, poor sealing at thermocouple insertion holes, poor sealing at vacuum gauge tube insertion points, and poor sealing at spare holes.
Solution: Replace the furnace cover sealing ring, inspect the furnace body and eliminate leaks, check the sealing condition of the vacuum system, clean and install the electrodes, reinstall the thermocouple, inspect and reinstall the vacuum gauge tube, and check the sealing of the spare hole.

3. Temperature uniformity fault
Poor temperature uniformity
Possible reasons: Unreasonable power distribution, open circuit of electric heating elements, unreasonable furnace structure leading to excessive local heat dissipation, poor furnace sealing leading to excessive local heat dissipation, uneven gas circulation or insufficient wind force in furnaces with fans, installation position or insertion depth of thermocouples cannot reflect the true temperature, unreasonable distribution of electric heating elements, low furnace bottom temperature, heating power supply phase loss or fuse breakage.
Solution: Recalculate and improve power configuration, replace disconnected electric heating elements, improve furnace structure or cooling methods, check furnace sealing and eliminate poor sealing factors, place workpieces reasonably and increase fan wind force, choose thermocouple installation position or insertion depth reasonably, adjust the distribution of electric heating elements, increase furnace bottom heating power, and check the heating power circuit.

4. Temperature control malfunction
Temperature control malfunction
Possible reasons: interference with temperature instruments, interference with thermocouple signals, poor contact of thermocouples, short circuit or open circuit of compensation wires, proximity of thermocouples to electric heating elements, malfunction of temperature control circuits, corrosion of thermocouples causing changes in electrical characteristics, and reduced insulation of thermocouples to ground protection tubes.
Solution: Eliminate interference sources, add shielding to signal lines, tighten thermocouple wiring terminals, check compensation wires and replace damaged parts, adjust the distance between thermocouples and electric heating elements, repair temperature control circuits, replace thermocouples, and check thermocouple insulation.
The temperature display value is too low
Possible reasons: high temperature at the reference end of the thermocouple, leakage of thermocouple electrodes, deterioration of thermocouple electrodes, measurement location of the thermocouple being too far away, mismatch between the compensation wire and the thermocouple, reverse polarity connection between the compensation wire and the thermocouple, and reduced insulation of the compensation wire.
Solution: Check the reference temperature and ensure it meets the requirements, check the electrode and wiring connections, replace the thermocouple, adjust the measurement position, replace the compensating wire and connect it correctly, and replace the compensating wire with reduced insulation.
Unstable temperature display
Possible reasons: poor contact of thermocouple electrodes, intermittent short circuit or open circuit of thermocouples, intermittent grounding of thermocouples, constantly changing position of thermocouples, grounding or intermittent short circuit or open circuit of compensation wires, and malfunction of temperature display instruments.
Solution: Reconnect the thermocouple and check the contact condition, check the thermocouple and eliminate the fault point or replace the damaged part, eliminate the grounding point and ensure the stability of the thermocouple position, check the compensation wire and eliminate the fault point or replace the damaged part, repair or replace the temperature display meter.

5. Other faults
Electric furnace wire circuit breaker
Possible cause: Aging or damage of the electric furnace wire.
Solution: Use a multimeter to check if the electric furnace wire is broken, and replace it with an electric furnace wire of the same specification.
Controller malfunction
Possible cause: Internal switch, fuse or furnace door travel switch malfunction in the controller.
Solution: Check the internal switches, fuses, and furnace door travel switches of the controller, and troubleshoot and repair them according to the controller manual.
Power failure
Possible reasons: damaged power cord, power switch malfunction, or blown fuse.
Solution: Check if the power cord is damaged and repair or replace it; Repair or replace faulty power switches; Replace the blown fuse and investigate the cause of the blow.
Abnormal noise inside the furnace
Possible reasons: Damage to furnace lining materials or unstable placement of workpieces inside the furnace.
Solution: Immediately shut down the furnace for inspection and identify the cause of the abnormal noise for processing; If the lining material is damaged, it should be repaired or replaced in a timely manner; If the workpiece is not placed stably, adjust the position of the workpiece again to ensure stability.

In summary, the box type resistance furnace may encounter various faults during use, but as long as the correct solutions are mastered, the faults can be promptly eliminated and the normal operation of the equipment can be ensured. At the same time, regular maintenance and upkeep of equipment is also an important measure to prevent malfunctions from occurring.