I watched a video on the production of ceramic tiles , as it turned out, this is a very complex and time-consuming process. What are the main stages? I would be grateful if you could explain what happens at each stage.
I watched a video on the production of ceramic tiles , as it turned out, this is a very complex and time-consuming process. What are the main stages? I would be grateful if you could explain what happens at each stage.
The answer to this question will require a significant amount of textual information.
Therefore, I will split the answer into several messages. In the first message I will list the main stages, and in subsequent messages I will consider each of them. The main stages of the technological process for the production of ceramic tiles consist of the following operations:
1. EXTRACTION OF RAW MATERIALS
2. PREPARATION OF CERAMIC MASS
3. MOLDING
4. DRYING
5. (GLAZING)
6. FIRMING
For those who have not yet seen a video on the production of ceramic tiles, I recommend watching it
The description of the Sokol plant presents a roller for the production of ceramic tiles and a roller for the production of agglomerate .
Clay is extracted in open pits using excavators and transported to the enterprise.
Quarry clay in its natural state is usually unsuitable for making pottery.
Therefore, it is specially processed to prepare the ceramic mass. When preparing clays, it is advisable to combine natural and mechanical processing. Natural processing involves aging pre-extracted clay for 1-2 years with periodic wetting by precipitation or artificial soaking and periodic freezing and thawing.
Mechanical processing is carried out with the aim of further destroying their natural structure, removing or crushing large inclusions, and removing harmful impurities.
There are two technologies for preparing the mixture: wet and dry.
In wet technology, raw ingredients are crushed and mixed in drum crushers in the presence of water.
Crushers are huge drums rotating around an axis: grinding parts (stones or balls) grind the mixture. As a result of grinding, an aqueous suspension of raw materials is obtained, which is called SLICKER. With dry technology, raw ingredients are crushed in hammer crushers and then moistened in special machines.
Wet grinding technology is more expensive, but gives much better results. The high degree of grinding of the raw material mixture ensures the uniformity and compactness of the shard during subsequent firing. The finished powder mixture is evaporated in chambers with hot air to the water content required by the molding technology. It is at this stage of the technological process that a mixture ready for molding is obtained with a given granule size and the required moisture content.
Dear Denis Enko, in your comments you use the term CERAMIC MASS . Could you clarify what you mean by that? According to my information, ceramic tiles contain not only clay, but also other inorganic materials: sand, ash, chalk, etc. You didn’t mention them at all. I would like to know what ingredients make up the ceramic mass.
I agree that for the presentation to be understandable, it is necessary to agree on concepts. I will list in more detail the raw materials that make up the ceramic mass.
Raw materials for the production of ceramic slabs are divided into two main groups: clayey (plastic) materials and non-clayey materials (wasting additives, fluxes or fluxes).
Clayey : monomineral (kaolin clays), polymineral (illite clays, bentonite clays, montmorilite clays).
Non-clayey : waste additives (quartz sand, fireclay, slag, ash), fluxes/fluxes (feldspar, dolomite, magnesite, chalk).
Leaning additives are introduced into plastic clays to reduce shrinkage during drying and firing and prevent deformations and cracks in products.
Fluxes (fluxes) are used to increase the sintering of clay and reduce the sintering temperature.
In accordance with European standards, molding is divided into three main groups: A, B, C. These groups indicate the water content in the ceramic mass and the method of its molding.
Molding A is a plastic molding method.
A plastic clay mass with a moisture content of 15-25% is formed by squeezing out timber. Molding is carried out using a vacuum belt press using the extrusion method. The ceramic mass is compressed by the screw of a belt press and pressed through a replaceable mouthpiece attached to the end of the output cylindrical part of the press, passing through which the plastic clay bar takes the shape of the corresponding ceramic product, i.e. the shape of a tile with a given thickness and width. A cutting device (thin wire), the operation of which is synchronized with the speed of movement of the clay bar, cuts the molded bar emerging from the mouthpiece of the press into pieces along the length of the tile, called a semi-finished product. The molded slabs come out of the press in doubles. After firing they are separated. Tiles produced by this method are called extruded and have a significant thickness of up to 30 mm.
Molding B – dry pressing, the so-called hard method.
Dry molded (pressed) tiles consist of a thoroughly mixed dispersed mass and are formed in a press under high pressure. The disadvantage of this method is that its metal consumption is almost 3 times higher than that of plastic (the number of technological operations increases, and, accordingly, the amount of production equipment used). Its advantage is that the duration of the production cycle is reduced by almost 2 times, the products have a more regular shape and more accurate dimensions. It is divided into semi-dry and dry methods. Semi-dry method .
Tiles using this method are formed from a mixture with a moisture content of 8-12%. Dry method . Press powder with this method is prepared with a moisture content of 2-6%. In this way, tiles with a compacted shard are produced: gres (stone-ceramic tiles) and porcelain stoneware.
Molding C is a slip method in which products are made from a multicomponent mass consisting of heterogeneous and difficult to sinter clays and additives. Products are cast from ceramic mass with a water content of up to 40%. This is the most ancient technology for molding ceramic tiles, but it is not widely used. Used for the manufacture of non-standard ceramic elements.
Before firing, the tiles must be dried to a moisture content of 5-6% to avoid shrinkage, cracking and distortion during firing. Drying is the movement of moisture from the inside of the product to the surface and its evaporation. The removal of moisture from the clay dough-like mass is accompanied by its shrinkage, the magnitude of which is proportional to the amount of evaporated water.
Previously, raw materials were dried mainly under natural conditions in drying sheds for 2-3 weeks, depending on climatic conditions. Currently, drying is carried out artificially in continuous tunnel dryers or periodic chamber dryers for from several to 72 hours, depending on the properties of the raw material and the moisture content of the raw material. Drying is carried out at a temperature of 120-150 degrees Celsius.
The main purpose of glazing is to obtain a surface layer with specified decorative effects and technological characteristics. Ceramic glaze gives the tile not only aesthetic characteristics - color, shine, decorative pattern, texture, but also technical properties: hardness, water resistance, ease of cleaning, and increases the wear resistance of ceramic floor tiles.
The glazing process is divided into two stages: preparing and applying the glaze. Preparation of glaze - grinding the recipe mixture in mills with the addition of water. Application of glaze is possible both dry and wet. With the wet method, the glaze looks like an aqueous suspension of finely ground ingredients, and with the dry method, it looks like granules.
For unglazed tiles, the glazing operation is not performed.
After loading the dried slabs onto trolleys, they are fired in a tunnel kiln more than 100 meters long. Trolleys with tiles, one after another, move along the kiln sequentially through the heating, firing and heating zones. The firing temperature program is maintained in accordance with the recipe composition of the slabs and the specified quality of the final product:
Firing is one of the stages of the technological process. However, the concepts of “single firing”, “double firing”, “three times firing” are not only a technological term, but also an indication of a certain type of tile.
Several firing technologies can be distinguished:
Thank you for the material on tile production technology. Could you tell us more about triple firing, and most importantly, why is it needed and where is it in demand? Or is it an atavism. After all, the cost of finished products in this case will increase significantly. Firing the tile three times is an expensive pleasure.
Triple firing – decorating tiles on a glazed surface, followed by firing (a fourth and fifth firing is possible) at a low temperature. Initially, this method was used in decorating dishes and porcelain.
Benefits of the third firing:
Triple firing involves the production of expensive tiles of high artistic value, which originate from hand-made tiles.