The Electromagnetic Stirring Technology in Continuous Casting Production
Continuous casting is a process wherein molten metal is poured into a mould and passed over an ablation plate that is moved into the middle of the casting mould, which solidifies the metal. Electromagnetic stirring (EMS) is one of the methods used to improve the quality of the cast product. EMS is a method used for stirring the liquid metal by using electric current and magnetic field that induces Lorentz forces and causes a secondary flow.
EMS is typically used to reduce porosity, improve distribution and enhance the surface quality. It can also be used to reduce the formation of non-metallic inclusions, which are particles of impurities that are entrapped in the cast material. EMS also improves the feedability of the molten metal and increases the life of the mould.
The EMS technique is performed by one or more induction coils connected to a power source. The coils can be set up in various configurations, depending on the geometry of the casting mould. In general, the currents induced in the liquid metal are low, ranging from 0.1 to 10A, but they can reach values up to 100A or more.
The technique works by inducing eddy currents in the liquid metal. These eddy currents are generated by the Lorentz force, which is the force that occurs when electric current interacts with a magnetic field, and causes a secondary flow. The currents induce a rotating flow structure in the liquid metal that entrains the molten metal, homogenizing the liquid and dispersing impurities. This improves the quality of the cast product by increasing the rate of mixing and promoting metallurgical reactions.
EMS has been used in the production of various cast products such as engine blocks, gearboxes and cylinder heads. It has been found to be especially effective in castings with complex shapes.
EMS is not only used for improving the quality of casting products, but also for enhancing the productivity and cost-effectiveness of the process. The process reduces the time needed for the start-up and complete the casting, since the stirring of the molten metal is more efficient than traditional stirring methods. The induction coils also minimize the energy losses that occur during the casting process.
EMS is an effective and efficient method for improving the quality and productivity of cast products. This technology is not only used in continuous casting, but also in other casting processes such as sand casting and die casting. The technique can be used in combination with other modern control systems such as heat treatment and computer simulation, to further improve the quality of the castings.
