This industrial furnace for heat treatment works periodically and is operated above a movable bell insulated with fiber-reinforced ceramic, which can be lifted and lowered. In this bell, which gives this furnace type its name, is the heating system that can be run on electricity, with gas or on oil. A high-performance circulator ensures a uniform heat supply. The workpieces are transported into the furnace from above in charging baskets carried by the overhead crane. If the charging has finished, the furnace is sealed off by lowering the bell. After the heat treatment process has been carried out, the bell is lifted, and the workpieces can be removed.
Use of such a type of furnace depends on the size and weight of the workpieces. Since each individual process can take place on the basis of a special firing program, this apparatus is particularly suitable for the production of small quantities or special products such as ceramic bonded grinding discs, electrical porcelain as well as extreme refractory materials. A bell-type furnace is also suitable for soft (spheroidize) annealing or normalizing of mass produced workpieces in the iron and steel industry.