The tiles’ manufacturing process makes for a mixed assortment of sophisticated technology exclusive to the industry. The tile technology or its manufacturing process is by no means a random system. Everything, from raw materials to the firing process, is there to make the system perfect.
Great quality tiles are not a product of any random system. On the contrary, these high-quality tiles are curated from a system that’s been in constant change and updates to deliver the best product. Today, we will see how the tile buy is created and its complex process structure.
It’s important to note that every kind of tiles have their own creative process, for which it’s so difficult to cover each one in a single article. We will cover the basics of tile technology through the process of ceramic tiles because I believe it’s the most similar process to every other kind of tiles in the market.
Once the raw materials are prepared, several steps take place to obtain the finished product. These steps include spray-drying, mixing and grinding, batching, forming, drying, firing, and glazing. Many of these steps are now automated for better accuracy.
- The body composition is defined by the amount and type of raw materials. The raw materials also restrict the tile body’s color, which can be red or white in color. It depends on the amount of iron-containing raw materials used.
- Therefore, it is essential to mix the right amounts together to achieve the desired properties. Batch computations are thus required, taking into consideration physical properties and chemical compositions of the raw materials. Once the suitable weight of each raw material is defined, the raw materials must be mixed together.
Mixing and Grinding
- Once the ingredients are registered, they are added together into a shell mixer, ribbon mixer, or intensive mixer. A shell component consists of two cylinders joined into a V, which turns to trip and mix the material.
- A ribbon appliance uses helical vanes, and an intensive mixer uses swiftly revolving plows. This particular step further grinds the ingredients, which results in a more excellent particle size that increases the subsequent forming process.
- Sometimes it is essential to add water to improve the mixing of a multiple-ingredient batch and achieve fine grinding. This simple process is called wet milling and is frequently performed utilizing a ball mill. The final result, the water-filled mixture is called a slurry or slip. The water is then removed from the mud by filter pressing, followed by dry milling.
- If wet milling is used first, the water in excess is usually removed via spray drying, which involves pumping the slurry to an atomizer consisting of a quickly rotating disk or nozzle.
- The droplets of the slip are dried as they are warmed by a rising hot air column, creating small, free-flowing granules that occur in a powder suitable for forming.
- Tile materials can also be prepared by dry grinding followed by granulation. Granulation employs a machine in which the mixture of earlier dry-ground material is mixed with water to form the particles into granules, which repeatedly form a powder ready for developing.
- In this process, the free-flowing powder—containing organic binder or a low percentage of moisture—flows from a hopper inside the forming die. The material is reduced in a steel cavity by steel plungers and is then ejected by the bottom plunger. Mechanical presses are used with operating demands as high as 2,400 tons.
- Several other processes are also practiced where the tile body is in a wetter, more new moldable form. Extrusion plus punching is in practice to produce an irregularly shaped tile and more porous tile faster and more economically.
- Then it involves compacting a plastic mass in a high-pressure cylinder and forcing the material to flow out of the barrel into short loafers. These loafers are then punched into one or more tiles applying hydraulic or pneumatic punching presses.
- Ram pressing is frequently used for massively profiled tiles. With this system, projected slugs of the tile body are clamped between two halves of a hard or porous shape mounted in a hydraulic press.
- The formed part is removed by first utilizing a vacuum to the top half of the mold to free the region from the bottom half, accompanied by forcing air through the top half to release the top part. Excess material must be removed from the role, and additional finishing may be needed.
- Another system of its kind, called pressure glazing, has latterly been developed. This process connects glazing and shaping concurrently by pressing the glaze directly in the die loaded with the tile body powder.
- Advantages include the elimination of glazing lines and the glazing waste material (called sludge) produced with the conventional method.
- Ceramic tiles typically must be dried at raised relative humidity after forming. Even more so, if a wet method is used. Drying, taking several days, removes the water at a slow rate to prevent shrinkage cracks. Tunnel driers are then used that are heated up using gas or oil, infrared lamps, or microwave energy.
- This kind of infrared drying is better suited for thin tile, whereas microwave drying works better for thicker tile. In another method called impulse drying, manufacturers use pulses of hot air flowing in the transverse direction instead of simultaneously doing it in the material flow direction.
- Synonymous methods are used for glazing when it comes to tile body. After a batch formulation is computed, the raw materials are balanced, mixed, and hard or wet milled.
- The milled glazes are then employed using one of the many methods available. In centrifugal glazing or icing, the enamel is fed through a rotating disc that flings or submits the glaze onto the tile.
- This stream of glaze falls onto the tile through the waterfall method as it passes on a conveyor underneath. Sometimes, the varnish is simply sprayed on.
- For multiple glaze applications, though, screen printing on, under, or between tile that has been wet glazed is practiced. And in this process, the glaze is forced into a screen by a rubber squeegee.
- Dry glazing is also in the contemporary scene. This means the application of crushed frits, powders, and granulated glazes onto a wet-glazed tile surface. After firing, though, the glaze particles melt into each other to produce a covering that seems like granite.
- Finally, after glazing, the tile must be heated strongly to strengthen it and give it the coveted porosity. Two types of ovens are used for firing the finished clay that is ceramic tiles.
- Wall tile, or tile that is made by dry grinding instead of wet milling, usually requires a two-step process. In this method, the tile goes through a low-temperature firing described bisque firing before the process of glazing. This particular step eliminates the volatiles from the material and most or all of the reduction.
- The body and glaze are then fired collectively in a process named glost firing. Both the firing processes take place in a tunnel or continuous system, which consists of a chamber. And through that chamber, the ware is slowly moved on the shelves built of materials that are resistant to high temperature or in containers called saggers.
- Firing in a tunnel kiln can take as long as two to three days, with firing temperatures around 2,400 degrees Fahrenheit, which is about 1,300 degrees Celsius.
- For tiles that only require a single firing—usually tiles prepared by wet milling—roller kilns are generally used. These kilns influence the wares on a roller conveyor and do not need kiln types of furniture, such as batts or saggers.
It’s important to note that firing times in roller kilns can be as low as an hour, with firing temperatures around 2,100 degrees Fahrenheit, which is about 1300 degrees Celsius.
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