External vacuum heat treatment furnace

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Advantages of external vacuum heat treatment furnace:

(1) the structure is simple, easy to manufacture and easy to operate and maintain.

(2) the volume of the vacuum tank is small, there are only processed workpieces in it, and the air volume is small, so it is easy to reach the required vacuum degree.

(3) the electric heating element is heated outside the vacuum tank (except for double vacuum), there is no vacuum discharge problem, and there is no other electrical problem (such as short circuit, carbon deposition, etc.), so the production is safe and reliable.

(4) the workpiece is sealed in the furnace and will not react with the electric heating element, furnace lining, etc.

Disadvantages of external vacuum heat treatment furnace:

(1) the heat source is outside the furnace, and the workpiece is heated by connecting the tank body, which is characterized by large thermal inertia, low thermal efficiency and slow heating speed.

(2) under high temperature and high pressure, the strength of the furnace is limited, the size of the furnace is small, the working temperature of the furnace is low, generally no more than 1100 ℃, and the vacuum degree is also low, generally no more than 10-100 Pa.

(3) a part of the furnace tank is exposed to the atmosphere, and the heat loss is large.

(4) the high temperature strength, welding quality and air tightness of the furnace and tank made of high alloy heat-resistant steel are required to be high, while the service life is short.

The external heat treatment vacuum furnace is usually only suitable for vacuum annealing, tempering, aging, degassing, metal infiltration, brazing and sintering of alloy.