A bell furnace is a type of industrial furnace used primarily for heat treatment processes, such as annealing, normalizing, and stress relieving of metal parts. The furnace is named for its bell-shaped design, with a circular base and a tapered roof that can be raised and lowered for loading and unloading. This bell furnace provides a controlled atmosphere for the heat treatment process, with the option for gas quenching or oil quenching to further enhance the properties of the metal.