vacuum brazing furnace failure analysis

According to the structural characteristics of vacuum brazing furnace, the possible causes of air leakage are analyzed. Vacuum brazing furnace is composed of furnace body, heating system, cooling system, control system, measuring system, vacuum pumping system, cooling water circulation system and gas charging system.

The factors affecting the leakage rate of vacuum brazing furnace are as follows:
(1) the external air leaks into the furnace chamber of vacuum brazing furnace to increase the leakage rate.
(2) the surface of aluminosilicate fiber felt inside the vacuum brazing furnace chamber is deflated, which makes the leakage rate increase.
(3) the leakage rate of vacuum brazing furnace chamber interlayer (including furnace door interlayer) and water pipe of gas cooling system increased.
(4) the internal leakage of vacuum valve and inflation group valve is not tight, which makes the leakage rate increase.

The factors affecting the limit vacuum of vacuum brazing furnace are as follows:
(1) the limit vacuum degree of vacuum system pump of vacuum brazing furnace decreases, which also makes the limit vacuum degree of cold furnace decrease.
(2) the effective pumping speed se of the pump decreases, which also makes the limit vacuum degree of the cold furnace decrease.
(3) with the increase of air leakage rate Q1, the limit vacuum degree of cold furnace decreases.
(4) the outgassing quantity Q2 on the surface of the insulating layer aluminosilicate fiber felt in the vacuum brazing furnace increases (or water and outgassing substances enter the furnace), which makes the limit vacuum degree of vacuum brazing furnace decrease in cold furnace.
(5) the measurement instrument is not accurate due to pollution, which affects the measurement of limit vacuum degree of cold furnace.

Analysis of the specific parts that affect the leakage rate of vacuum brazing furnace
(1) the external leakage parts of vacuum brazing furnace body include: furnace door seal, main valve stem seal, pneumatic ball valve stem seal, vent valve spool seal, explosion-proof valve core seal, pre extraction valve stem seal, thermocouple seal, heating electrode seal, etc.
(2) the inner wall surface of vacuum brazing furnace is deflated.
(3) there is water leakage in the interlayer of vacuum brazing furnace chamber (including the interlayer of furnace door) and the water pipe of gas cooling system.
(4) there is air leakage inside the valve body of the pre extraction valve, and the internal air leakage of the charging valve (high vacuum pneumatic butterfly valve), make-up valve and partial pressure group valve (pressure reducing valve, fine-tuning valve, solenoid valve) in the inflation group valve.

Analysis of the specific parts that affect the limit vacuum degree of vacuum brazing furnace
(1) the limit vacuum degree of slide valve pump in vacuum system of vacuum brazing furnace is reduced.
(2) the limit vacuum degree of roots pump in vacuum system of vacuum brazing furnace is reduced.
(3) the limiting vacuum degree of diffusion pump in vacuum system of vacuum brazing furnace is reduced.
(4) there is air leakage in the sealing parts of the pipeline connecting the slide valve pump, roots pump and diffusion pump, the valve stem seal of the front stage valve, and the seal of the explosion-proof device.
(5) leakage of vacuum brazing furnace body.
(6) the measurement instruments and regulations of vacuum measurement system of vacuum brazing furnace are inaccurate due to pollution. According to the above analysis of the vacuum technical indexes and possible fault parts of the vacuum brazing furnace, it is suggested to carry out maintenance.

Learn More : Vacuum Sintering Furnace