How Ardogres Tiles are made

How Ardogres Tiles are made

PRESSING, GLAZING AND FIRING OF TILES

The processing stages of stoneware tiles
porcelain tiles involve the following steps:

Preparation of clays
Pressing and drying
Glazing
Heat treatment with drying and firing

Once the powders have been ground, we then proceed to the stage
Of pressing the mixture.

Pressing and drying
Pressing involves compressing the starting material in a mold.
It may be uniaxial dry and wet, isostatic cold and hot.
The application of pressure, while the material is still in the state
solid, allows a reduction in the void fraction due to the change
of the shape of the granules. For porcelain stoneware tiles, the following is used
mainly uniaxial wet pressing because the clay materials
used as raw materials contain about 10 percent water inside.
These materials subjected to the action of pressure, deform
plastically and assume the shape of the mold cavity.
The resulting product immediately undergoes a drying process to
remove excess moisture. Typically, dryers are used
vertical or horizontal

Glazing
The pressed and dried tile heads to the glazing line. This
is equipped with various machines dedicated to the application of glazes and materials
materials (e.g., grits), as well as the HD digital printer that imprints the
tile the desired graphics.
This last machine represents the most important technological innovation
in the last 10 years and has finally allowed ceramics, and stoneware
porcelain tile specifically, to achieve a degree of definition
comparable to that of natural materials.
The glaze will contribute, along with the body, to improving the characteristics
technical properties of the tile, including strength and frost resistance.

Firing
This is the process by which small particles of a material are
consolidated through casting. During this process the material is
heated to very high temperatures, above 1,200°C; this
gradually increases the mobility of the atoms of the material within and
especially along the surface of the powder particles.
Diffusion processes tend to reduce the free surfaces by welding the grains together; they are
voids between grain and grain are also gradually reduced in this way, and the
density of the material increases. Sintering involves very
high and can take place under pressure or without pressure.
Sintering occurs through three stages:

- in the first stage, a rearrangement of the particles is observed and the system
is likened to a set of uniform spheres with the formation of necks and
of the first bonds at the contact points between the particles.
- In the second stage, the system is represented as a set of grains
uniform with common faces and cylindrical pores along the edges of the grains. At the beginning
of the stage the porous phase is considered continuous; there is a
decrease in porosity and an approximation between particle centers,
which cause a shrinkage equivalent to the reduction in porosity. This stage is the
responsible for most of the shrinkage.
- In the third stage there are isolated pores in each of the corners of the grain. The
residual porosity is eliminated by vacation diffusion along the edge of the
grains.
Three different mechanisms can occur in sintering, among which should be
include vitrification (viscous sintering) by which are
sintered most conventional ceramic materials. In this phase
there is the formation of a liquid phase accompanied by the subsequent
elimination of the gas phase and intergranular pores.
The liquid phase, in fact, goes between the pores of the particles. During
the elimination of pores and bubbles, the reduction of surface area occurs
which leads to densification. During the cooling phase, the liquid gives
originates a glassy phase.
The firing phase generally takes place by means of special roller kilns, equipped with
with all the mechanisms to control the product during this process.
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