At ceramitec, Refratechnik Ceramics presented an innovative “base frame” for roofing tile firing. When tiles are fired in H-setters, breakage often occurs at the feet of the setters. One reason for this is, firstly, the different thermal expansion coefficients of the cassettes compared to the bearing elements of the kiln car level.
Secondly, the left and the right foot of the cassette stack are usually each placed on separate support elements, which has the effect that during the heating and cooling operation the changes in length run in opposite directions, resulting in high friction forces. This stress occurs during each furnace run and facilitates damage to the cassette feet in the form of flaking or even malfunction of the cassette.
These problems can be eliminated with the use of a cast base frame. The base frame, which consists of the same material as the cassette, accommodates the cassette stack as a solid component. Thus, the size and direction of the length changes in the thermal process are identical, which minimises the damaging frictional forces and optimally protects the feet.
The base frame is statically more stable in design than the H-setter, so also stresses caused by movements in the kiln car deck can be accommodated. This means that fewer deformation forces pass into the setter.
The operator benefits from a lower breakage rate and therefore from a longer lifetime of the setters.