The lining of medium frequency furnace depends on the size of the furnace to decide whether to use castable or ramming material.

In general, castables are used for small furnaces, i.e. 1 ton medium frequency furnaces. In the case of vacuum furnaces, castables are first made into crucibles, baked at 1200 ℃ and directly put into the furnace lining for use. For larger furnace linings, such as medium frequency furnaces with more than 15 tons, refractory ramming materials are used as lining materials.

The material of crucible castable is the same as that of large tonnage furnace lining ramming material. Aluminum magnesium spinel castable is used. However, the particles have a certain limit, and the particles of castable are between 0-3. The particle size of ramming material is 0-5mm, and the largest is 0-7mm. The refractory ramming material is rammed on site. Because the amount of water added to the ramming material is small, it is good for the lining baking of the medium frequency furnace.

If we say that the castable for the lining of vacuum furnace with small tonnage can also be constructed on site, but there are few manufacturers with such construction, because the furnace lining is small, it is difficult to pour. It is better to directly pour a crucible with the same shape as the furnace lining in the casting material manufacturer, send it to the manufacturer after barbecue, and directly put it into the lining for use. This will be better.

Whether castable or ramming material is used, it also depends on the material determined by the atmosphere of the medium frequency furnace. If it is acidic, acidic material shall be used as fire-resistant ramming material. If it is neutral, plate-shaped corundum or white corundum shall be used as corundum ramming material. If the furnace lining is alkaline, alkaline materials should be used as ramming materials.

As the service condition of medium frequency furnace is not sustainable, the ramming material made of alkaline material has thermal shock, which is not as good as neutral material. With the continuous improvement of practical use, aluminum magnesium spinel ramming material is used as cladding. In this way, the problem of thermal shock is solved, and the atmosphere of the material is basically consistent with that of the lining. In this way, castables with alkaline lining atmosphere or refractory ramming materials are used more often.