FIRING ZONE : The material moves more along the sides and less in the center.
COOLING ZONE : The material moves more through the center than through the sides.
One of the causes is that the material softens with heat and by its own weight.
If the plane of the rollers does not present a more rectilinear advance, one roller marked with its taper can be placed in an orderly and alternating manner at the handling end and another marked at the bearing support end, also in blocks of 5 or 10 equal rolls at the handling end and another 5 or 10 equal at the supporting end, perhaps with 40 / 50 rolls until the exit from the cooking area .
ALWAYS ONE ROLLER IN THE HANDLING AREA AND ONE ROLLER IN THE SUPPORT AREA
Depending on the degree of deceleration in the centre of the kiln rollers, this formula may also have to be used from the preheating zone until the start of the cooking zone, which is approximately 10 metres long and temperatures ranging between 700 and 900 ºC
Quick cooling zone
Mixing rollers (SILICON CARBIDE + CORDIERITE) have been created for this area, which prevent the deformation of the rollers and the material between the last cooking zone (+1,180oC) and the first quick-cooling zone , produced by the blow-off tubes at +610oC; since silicon carbide has a higher THERMAL CONDUCTIVITY and a low coefficient of expansion, it is better able to withstand such temperature differences.
General information
The heat treatment of the material in the ceramic kiln goes through different critical phases, each with specific effects on the material properties:
- From 0 to 100 °C: moisture is removed from the tile
- From 200 to 400 °C: the combustion of organic matter (glycols, fixators, granule tails…) .
- At 572 °C: the transformation of quartz from ALPHA phase to BETA phase (dimensional change effect, volume increase)
- Sodium, potassium and calcium are flux which lower the melting temperature of other raw materials.
Important information
When the various contaminants are incorporated into the roller matrix, new crystalline phases with different expansion coefficients are generated, thus modifying the homogeneous structure of the roller.
