by convection. As the electrical energy heats the heating elements that then heat the mold in a secondary manner, the process is called indirect resistance heating.

Advantages are high achievable temperatures, independent from the conductivity of the mold and independent from heat and pressure. Main disadvantage is the time that it takes to heat up the mold. It takes relatively long for heat transfer to take place from the furnace atmosphere to the mold surface and subsequently throughout the cross-section