The electromagnetic forces acting on the molten metal within an induction furnace, force the molten product into the center of the furnace where it rises to the top. This circulation of the molten bath, i.e. bath agitation, always forms an elevation (convex meniscus height) and ensures rapid heat and material exchange and facilitates stir-in of cold charge materials added from above.
However, it must be stated that bath agitation always depends on the operation frequency and the power consumption of the furnace. For example, if a 5-t-Nf furnace with 1000 kW (= 200 kW/t) is only charged with 3 t of material, and if the current power is at 900 kW, the specific power is 900/3 = 300 kW/t. From this value it can be deduced that a particularly high degree of bath agitation is achieved. In other words: if the furnace needs to be carburized, this should be performed in partly-filled condition. Moreover, bath agitation prevents accumulation of heat and overheating in the rim zone of the furnace (energy transfer zone).
Bath agitation provides a number of benefits for melting materials with low specific weight, such as chips or stamping scraps. Bath agitation also is beneficial for alloying and provides a certain cleaning effect for the molten metal. Since bath agitation causes constantly recirculating contact of the molten bath with the atmosphere, an increased tendency towards oxygen and hydrogen absorption (s. Hydrogen solubility) cannot be prevented.