The vacuum furnace is generally composed of the main engine, the furnace chamber, the electric heating device, the sealed furnace shell, the vacuum system, the power supply system, the temperature control system and the external transport vehicle. The sealed furnace shell is welded of carbon steel or stainless steel, and the joint surfaces of the detachable parts are sealed with a vacuum sealing material. In order to prevent the furnace shell from deforming after heating and the sealing material from deteriorating when heated, the furnace shell is generally cooled with water or air cooling. The furnace chamber is located inside a sealed furnace shell. Depending on the furnace purpose, the furnace chamber is equipped with different types of heating elements, such as resistors, induction coils, electrodes, and electron guns. Vacuum furnaces for smelting metal are equipped with crucibles, and some are equipped with automatic pouring devices and manipulators for loading and unloading. The vacuum system is mainly composed of a vacuum pump, a vacuum valve and a vacuum gauge.