Induction furnaces are classified into two main categories based on their structure: crucible type (usually called coreless induction furnace) and channel type (usually called cored induction furnace). Crucible type furnaces are further classified by frequency into power frequency and medium frequency. Channel type furnaces can be divided into vertical and horizontal types.
In the casting field, induction furnaces have three uses: melting, holding, and pouring. Therefore, they are also classified into melting furnaces, holding furnaces, and pouring furnaces according to their use.
Power frequency crucible induction furnaces are mainly used for melting cast iron and non-ferrous metals. Due to the strong electromagnetic stirring force, the furnace lining life is very short when melting steel; therefore, it is not suitable for steelmaking unless the refractory material lifespan problem can be solved. It is also not suitable for non-ferrous metals with strict gas content requirements (such as oxygen-free copper). When a power frequency crucible induction furnace is used as a holding furnace, the induction coil is shorter, approximately 1/4 of the crucible height.
Medium frequency crucible induction furnaces (medium frequency induction furnace) are suitable for melting and holding steel and non-ferrous metals. Compared with power frequency crucible induction furnaces, the advantages of medium frequency crucible induction furnaces are high power density, easy starting, no need for a three-phase balancing device, and smaller furnace size under the same production rate. Because it can be emptied, it is more convenient to change metal types.
The characteristics of crucible induction furnaces are that the furnace lining shape is simple, furnace construction is convenient, and the furnace lining is easy to inspect and repair, and it can be started and stopped as needed.
Channel type induction furnaces are mainly used for melting and holding non-ferrous metals such as copper, aluminum, and zinc, and for holding cast iron, as well as for use as pouring furnaces on casting lines.
The characteristics of channel type induction furnaces are that the electrical efficiency and power factor are higher than those of crucible induction furnaces. The disadvantages are that the refractory material in the channel section is difficult to inspect and repair, and current is needed for holding even when not in production, making it difficult to change metal types. It is more suitable for single-variety production.
