Bell Furnaces

The advantage with Bell furnace processing versus continuous furnace processing is mainly that the cooling process can be more closely controlled. For example a long cooling period with the temperature held at the AR1 (Arret refrois) point in the steel carbon diagram will result in the formation of large perlite crystal structure in the steel producing a soft malleable and ductile wire suitable for cold heading.

Another advantage with Bell Furnaces is that the convection system can not only transfer the heat homogeneous and faster, but the convection-speed can also be adjusted to the temperature of the annealed wire i.e. Convection speed can be automatically changed with the annealing heat.

There are two basic types of bell furnaces. The vacuum furnace and the protective (inert) gas furnace.

The vacuum furnace as well as the protective (inert) gas furnace will both produce a wire surface free from oxide suitable for plating or coating.

The vacuum furnace is more energy efficient and is gaining market share.