1.Àü±â µµ°¡´Ï·Î(electric crucible furnace)

Electric crucible furnaces are similar to gas fired-crucible furnaces, but utilize electric resistance-heating elements to heat the crucible and melt the aluminum. Like their gas counterpart, electric crucible furnaces are small and are typically used when alloy flexibility is the most important.
Advantages provided by the electric crucible furnace is the near elimination of emissions and low metal oxidation losses. Disadvantages include increased fuel costs and size limitation.

Crucible furnaces are not as efficient as reverberatory furnaces because the heat must be transferred through the walls of a crucible to the metal to be melted. Crucible furnaces come in three types, the lift-out crucible type, where the crucible is used as a ladle, the stationary crucible type where the aluminum is dipped out with a ladle and the tilting crucible type where the metal is poured directly from the furnace.
Crucible furnaces generally have between 3 to 5 inches of refractory that is rammed or poured inside a steel shell.
The efficiency of crucible furnaces range from a low 3.5% to a high of 28% the common commercial average being around 15%. The average heat input to melt aluminum is approximately 3300 Btu per pound.

The efficiency of a furnace is the ratio of heat input to useful output. To calculate the furnace efficiency you divide the theoretical amount of heat needed by the actual amount of heat used to melt a specific amount of metal.