During firing in H-cassettes, spalling of the cassette feet occurs frequently. One cause is the different thermal expansion of the cassettes compared with the supporting elements that are normally used. This results in high frictional forces. These stresses occur during every kiln run, and inevitably lead to damaged cassette feet as well as spalling that can even result in failure of the cassette.
This problem can be eliminated by means of a cast base frame. Thermal expansion of cassette and base frame occurs in the same direction, because both components – cassette and base frame – are made of the same material. In this way, equal coefficients of thermal expansion are ensured. The damaging frictional forces are eliminated, and the cassette feet are optimally protected.
Because the base frame is statically stronger than the H-cassette, stresses due to movements at the kiln car level can also be absorbed.
The kiln operator benefits from a lower breakage rate and thereby from longer service lives of the cassettes.