Body preparation and forming
The vast range of products, which includes cotto (a red porous product made of natural clays), klinker (a low-porosity product made with ceramic compositions) and true porcelain tiles (virtually zero porosity), will evidently require very different preparation systems. The most widespread system is dry grinding, in which different mills
are employed as a function of required product particle size distribution and raw material hardness. The ground clays are then sieved, stored in silos and batched to obtain the required formula.
Continuous or intermittent mixing/moisturising follows: here, mixing is combined with the degree of wetting that is appropriate for subsequent extrusion.
Preparation may make use of spray-dried bodies where final product quality so requires.
Forming takes place in de-airing extruders specially studied for flat extrusion of even the largest (600x600, 600x900), low thickness (6-12 mm) products. All accessories (pressure head, moulds) have been specially designed.