The vacuum degree of the vertical graphite carbon tube vacuum furnace cannot be pulled up

10-17-2025       Author: KJ technology

The vacuum degree of the vertical graphite carbon tube vacuum furnace cannot be drawn up, which may be caused by various reasons such as vacuum pump failure, seal problems, leaks, heating element or control system failures, cooling system problems, material deflation, etc. The following are specific analysis and solutions:

1. Vacuum pump malfunction

Possible reasons: pump oil contamination, insufficient or too thin, poor or damaged vacuum pump operation, pump overheating, mechanical expansion leading to small gaps, improper cleaning causing debris to enter the oil.

Solution: Clean the vacuum pump, replace with new vacuum pump oil, replace with a new pump, strengthen the cooling of the pump, check if the power supply is normal, repair or replace damaged vacuum pump parts.

2. Sealing component issue

Possible reasons: aging, corrosion, or damage of seals, loose connections at pipeline joints, air leakage from solenoid valves, pipe joints, vacuum pump suction valves, and sealing gaskets around the working chamber.

Solution: Check and replace aging or broken seals to ensure good sealing, inspect pipeline connections, solenoid valves, pipe joints, etc., and repair or replace them.

3. Leakage issue

Possible reasons: There are leakage points in the furnace body, such as cracking of furnace shell welds, leakage of heat exchangers, leakage of valves, etc.

Solution:

Leakage detection: Using the flame method and the principle that airflow can cause the flame to deviate, gradually search near the suspicious point. If the flame deviates towards the leakage point, the leakage point can be found.

Internal leakage detection: After the vacuum system reaches a certain pressure value, start the winding and evaporation systems respectively, observe whether the reading of the vacuum gauge rises after a brief decrease, and preliminarily determine the direction of the internal leakage point. Internal leakage often occurs on equipment with water cooling points. You can clean the chamber first, then pass cooling water, and carefully check whether there are any wet points in the water pipeline. Wet points are the leakage points.

Repair leakage points: Based on the location and type of leakage points, repair them by welding, replacing seals, and other methods.

4. Heating element or control system malfunction

Possible reasons: aging, damage or poor contact of heating elements, burning of heating strips, burning of heating wires; The temperature controller is damaged or improperly set, the thermocouple wire is broken or short circuited, and the temperature control instrument is malfunctioning.

Solution: Check the connection and resistance of the heating element, repair or replace damaged heating elements; Check and adjust the settings of the thermostat, replace or reconnect the thermocouple, and repair the control system.

5. Cooling system issues

Possible reasons: insufficient cooling water supply, blockage of cooling system, etc.

Solution: Check if the cooling water pipeline is unobstructed, ensure sufficient cooling water supply, and clean any blockages.

6. Material deflation

Possible reasons: moisture absorption on the inner wall of the furnace shell, air release from insulation materials, air release from heat exchangers, air release from fixtures used by brazing workers in the furnace, and air release from materials of products to be brazed.

Solution: Perform oven drying treatment to remove gases from the material. For the issue of heat exchanger venting, filling gas after baking and starting the fan for hot air circulation may help solve it.