Methods for making linings of induction metling furnace

According to the size of the crucible, the forming methods of the crucibles for the linings of medium frequency furnaces can be roughly divided into four types: mortar casting, pressure molding, furnace molding and masonry. The first two methods are mainly used to make small-capacity (less than 100kg) crucibles, and the latter two methods are suitable for making medium and large-capacity crucibles.

1. Mortar casting method

 This crucible forming method is suitable for making special refractory crucibles with a capacity of less than 25kg, such as crucibles made of materials such as CaO, BeO, ZrO2, ThO2, Al2O3, etc.

2. Pressure molding method

 The sand material for making the crucible is mixed evenly according to different particle size ratios, loaded into the pressure molding mold, and pressure is applied to shape it. The pressure molding method can be divided into two methods: simple pressure molding and isostatic pressing.

a) Simple pressure molding is to load the sand material into the mold cavity before applying pressure, and the upper and lower pressure heads are pressed in different directions to form the crucible blank. The sand material should contain a certain amount of water and additives or adhesives. After demolding, it can be used after drying and high-temperature sintering. It can also be placed in the inductor and sintered by the temperature of the molten steel.

b) Cold isostatic pressing is a powder metallurgy forming process, which is to apply equal pressure to the entire surface of the pressed object. In other words, the pressure at each point on the surface of the pressed object is exactly the same, so it is called isostatic pressing. Since the pressed object is not heated during the pressing process, it is also called cold isostatic pressing.

3. Furnace forming method

Furnace forming method is a widely used crucible forming method. It is suitable for crucibles of different capacities. The furnace forming method is divided into manual ramming forming method and mechanical vibration forming method.

4. Masonry method

 The masonry method is to use special refractory bricks to build a crucible in the furnace. This method is suitable for hot-charged large induction furnace crucibles. Crucibles above 5 tons can be used. The advantages of this method of building crucibles are short production time, easy replacement, no need for furnace-building machinery and cores, and the use of prefabricated refractory bricks can ensure stable quality and reduce baking time.