External heat vacuum heat treatment furnace

Thermal vacuum heat treatment furnace has low manufacturing cost and its structure is similar to that of ordinary resistance furnace. External heated vacuum heat treatment furnace has a can into a vacuum sealed cans, processed workpiece loading tank, and heating elements, refractory materials, insulation materials, furnace are outside the tank, heating furnace tank from the outside, so also known as hot fireplace. The furnace can usually be cylindrical, in either horizontal or vertical direction in the furnace body or partly out of the furnace to form a cooling chamber.
Advantages of external heat vacuum heat treatment furnace:
(1) simple structure, easy to manufacture, easy to operate and maintain.
(2) small vacuum tank volume, which is only handled by the workpiece, and has less air volume, which can easily reach the vacuum degree required.
(3) the heating element is heated outside the vacuum tank (except double vacuum), there is no vacuum discharge problem, no other electric (such as short circuit, carbon, etc.) problems, and the production is safe and reliable.
(4) the workpiece is sealed in the furnace and will not react with the electric heating element or furnace lining.

Disadvantages of external heat vacuum heat treatment furnace:
(1) the heat source is outside the boiler, and the workpiece is heated by the tank, and the thermal inertia is large, the thermal efficiency is low and the heating speed is slow.
(2) the furnace tank strength under high temperature and high pressure is restricted, the furnace tank size is small, low working temperature of the furnace, generally no more than 1100 ℃, vacuum degree is low, generally less than lO ~ lOOPa.
(3) part of the furnace can be exposed to the atmosphere, and the heat loss is large.
(4) the high temperature strength, welding quality and air tightness requirement of the furnace can be high, and the service life is short.