A method including preheating a set of N shell molds for lost-wax casting, where the method can comprise: individually charging shell molds into n unit electric furnaces, each of which has previously been preheated to an initial loading temperature; starting a predefined preheating cycle for each shell mold charged in the unit electric furnaces, with a preheating cycle comprising raising the temperature of the furnace in compliance with a predefined ramp up to a predetermined setpoint temperature, and holding the furnace at the setpoint temperature for a predetermined duration; and at the end of each preheating cycle, unloading the shell mold in question and repeating the two preceding operations for another non-preheated shell mold.