Ceramic tile manufacturing process - materials, manufacture, making, use, dimensions, composition,

Background

White wares are a group of ceramics that produce wall and floor tiles for exterior and interior decoration. Tile production dates back to ancient times when the tile was made by many people, such as the Babylonians, Egyptians, and Assyrians. The Step Pyramid for Pharaoh Josher was built in ancient Egypt at approximately 2600 B.C. It contained colorful glazed tiles. Ceramic tile was later manufactured in almost every country in Europe and the United States. The tile was first manufactured industrially at the turn of the 20th century. In 1910, the invention of the tunnel oven made tile production more automated. Tile manufacturing is now highly automated.

The American National Standards Institute divides tiles into different classifications. Ceramic mosaic tile can be porcelain tiles or natural clay of fewer than 39 cm2 (6 inches). Decorative wall tiles are glazed with a thin body that can be used to decorate residential walls. Paver tile can be glazed or unglazed porcelain or natural clay tile measuring 39 cm2 (6 inches) or more. Porcelain tile can be either ceramic mosaic tile, paver tile, or tile made from clay. It is produced using a specific method known as dry pressing. Quarried tile can be glazed or unglazed and is the same size as paver tiles, but it's made using a different form.

Europe, Latin America, and the Far East are the three largest producers of tile. Italy is the world's leading producer, with 16.6 million feet per day as of 1989. Spain (12.6%), Brazil (11.2%), and Germany (both 11.2%) are the following most significant producers of tile. The United States is 4.5 percent. According to one estimate, the total market for wall and floor tiles was $2.4 billion in 1990.

According to the U.S. Department of Commerce, there are approximately 100 ceramic tile manufacturing plants in America. In 1990, they shipped 507 million feet2 of ceramic tile. The volume of U.S. imports in 1990 was around 60%, with a value of approximately $500 million. Italy is responsible for nearly half of all senses. Mexico and Spain follow. The U.S. has seen some growth in exports, rising from $12 million in 1988 and $20 million in 1990.

The industry of tile is an established market that is dependent on the construction industry, so that growth will be slow. The United States Department of Commerce predicts a 3-4 percent increase in tile usage over the next five years. A second economic analysis projects that 494 million feet2 of tile will be shipped in 1992. This is a 4 percent increase over the previous year. Some tile manufacturers are more optimistic. An American Ceramic Society survey found that each manufacturer saw an average growth rate of 36 percent over the next five years.

Raw Materials

Clay minerals from the earth's crust are used to make tiles. They also include natural minerals like feldspar, which can be used to lower the firing temperatures, as well as chemical additives that can be used for shaping. Before being shipped to the ceramic plant, the minerals are often processed or beneficial close to the mine.

Pulverizing the raw materials is necessary to determine their particle size. To reduce large amounts of material, primary crushers are used. A jaw crusher, gyratory, or both can be used to reduce large lumps of material. They operate by using a horizontal

Mixing the ingredients is the first step of ceramic tile manufacturing. Sometimes the water is added to the mixture, and the elements are then wet milled or ground in a mill. If wet milling is employed, excess water is removed by filter pressing and then spray drying. The powder is then pressed into the desired shape for the tile body.

I am squeezing motion between steel plates or rotating motion between steel cones, respectively.

Secondary crushing reduces the size of smaller lumps into particles. Muller or hammer mills are frequently used. Muller mills use steel wheels in a shallow, rotating tray, while hammer mills use steel hammers that move quickly to crush the material. You can also use a cone or roller crushers.

It may be necessary to perform the third step in order to reduce the particle size. Combining grinding media with tumbling mills is a good option. The ball mill is one of the most popular types. It consists of a large rotating cylindrical that is partially filled with spherical media.

Screens can be used to remove particles within a specified size range. Screens are sloped and vibrated electromagnetically or mechanically to increase material flow. The mesh number is the number per inch of screen surface openings. The smaller the opening size, the higher the mesh number.

Glazes are glass materials that melt onto tile surfaces during firing and then stick to them during cooling. Glazes can be used for decoration and moisture resistance.

The Manufacturing Process

After the raw materials have been processed, there are many steps that must be followed to produce the final product. These steps include mixing, spray drying, drying, drying, glazing, and firing. Automated equipment is used for many of these steps.

Batching

• 1 The amount and type of raw materials determine the composition of many ceramic products, including tiles. The color of the tile body is also determined by the raw materials. Depending on how much iron-containing material was used, it can turn red or white. Mixing the right amount of raw materials together is crucial to obtaining the desired properties. Batch calculations are therefore required. They must consider both the physical and chemical properties of the raw materials. After determining the weight of each raw material, it is time to mix them together.

Mixing and Grinding

• 2 After the ingredients have been weighed; they can be added to a shell mixer or ribbon mixer. A shell mixer is made up of two cylinders connected into a V that rotates to mix and tumble the material. The ribbon mixer uses helical vanes, while the intensive mixer uses rapidly rotating plows. This further grinds the ingredients. This improves the subsequent forming (see step #4).

• It is sometimes necessary to add water to enhance the mixing of multiple components and to fine grind. This is known as wet milling. It is usually done with a ball mill. The resultant water-filled mixture is known as a slip or slurry. After filter pressing, which removes 40-50% of the moisture, the water is removed from the slurry. Dry milling follows.

Spray drying

• 3 When wet milling is used for the first time, excess water can be removed by spray drying. This involves pumping the slurry into an atomizer, which is a rotating disk or nozzle. The heat from the rising hot air column causes slip droplets to dry and form small, free-flowing granules. This powder is suitable for molding.

• Dry grinding and granulation can also be used to prepare tile bodies. Granulation is a process in which a mixture of dry-ground materials and water is combined with water to form granules. This powder can then be used for shaping.

Forming

• Dry pressing is the most common method of making tile. This method involves the free-flowing powder, which may contain an organic binder or low moisture content. It flows from a hopper to the forming die. The steel plungers compress the material in a steel cavity, and then the bottom plunger ejects it. The operating pressure of automated presses can reach 2,500 tons.

• There are many other options available when the tile body is in a more mold able, wetter form. To produce tiles with irregular shapes and smaller tiles more efficiently, extrusion plus punching can be used. The process involves compressing a mass of plastic in a high-pressure cylinder and forcing it to flow out of that cylinder into short, flat slugs. The slugs can then be punched into tiles by using pneumatic or hydraulic punching presses.

• For tiles with high profiles, Ram pressing is often used. This method involves pressing the extruded slugs from the tile body between two halves of a porous or complex mold in a hydraulic press. To remove the formed part, first, apply a vacuum to the top of the mold to release it from the bottom. Then force air through the top to loosen the lid. Additional finishing may be required if excess material is left on the part.

• Pressure glazing is another process that has been recently developed. This method combines shaping and glazing by pressing the glaze in spray-dried powder form directly into the die filled with tile body powder. This process has many advantages, including the elimination of glazing lines and the removal of the glazing waste material (called "sludge") that is generated with the traditional method.

Drying

• After forming ceramic tiles, it is essential to dry them (at high relative humidity), primarily if they were developed using a wet process. The drying process, which can take several hours, removes water at a sufficient rate to prevent cracking. These driers can be either continuous or tunnel. They are heated with oil, gas, infrared lamps, or microwave energy. For thin tiles, microwave drying is more suitable. Impulse drying is another method that uses hot air in pulses and flows in the transverse direction rather than continuously in the material flow.

Glazing

• Similar methods are used to prepare the glaze as for the tile body. Once a batch formula has been calculated, the raw materials must be weighed, mixed, dried, or wet milled. One of many ways to apply the milled glazes is to use one of the many options. The ice is fed through rotating discs that throw or fling the glaze onto the tile in centrifugal glazing. The bell/waterfall method uses a stream of glaze that falls onto the tile when it passes underneath a conveyor. Sometimes the ice can be sprayed. Screen printing can be used to apply multiple glazes on tiles that have been wet glazed. This involves forcing a glaze through a screen using a rubber squeegee or another device.

• Also, dry glazing is being used. This is done by applying powders, crushed Frits (glass material), and granulated glazing to a wet-glazed tile floor. The glaze particles will melt together after firing to create a granite-like surface.

Firing

• 7 The tile should be heated to a high temperature after glazing. This will strengthen the tile and increase its porosity. There are two types of ovens:

• The file is then dried at high humidity for several days to prevent shrinkage and cracking. The glaze is then applied, and the tile is fired in either a furnace or kiln. Some types of tile require two-step firing, but wet-milled tiles are fired once at temperatures up to 2,000 F. The tile is then packed and shipped after it has been fired.

• For firing tiles, kilns are used. For wall tile (or tile prepared by dry grinding rather than wet milling), there is usually a two-step process. The tile is then subject to a low-temperature firing known as bisque firing before being glazed. This removes volatile and shrinkage. Glost firing is the process by which the glaze and body are combined. Both firings take place in a continuous kiln or tunnel. This chamber houses a chamber through which the ware is moved slowly on a conveyor using refractory batts (shelves made of materials that resist high temperatures) or in containers called "saggers." A tunnel kiln can be fired in two to three days at temperatures of 2,372°F (1,300° Celsius), with firing temperatures between 2,372 and 1,300 degrees Celsius.

• Roller kilns can be used for tile that requires only one firing. This is usually tile that has been prepared by wet milling. These kilns are used to move the wares along a roller conveyor. They do not require any kiln furniture like batts or shaggers. The firing temperature at 2,102 Fahrenheit (1.150 Celsius) can take as little as 60 minutes in roller kilns.

• 8 The tile is now ready for shipping after it has been fired and tested.

Byproducts

There are many pollutants that can be generated by the manufacturing process. These emissions need to be controlled in order to comply with air control standards. Fluorine and lead compounds are two of the most common pollutants in tile manufacturing. These are also produced during firing and glazing. The recent development of low-lead and no-lead glazes has significantly reduced lead compounds. Scrubbers can be used to minimize fluorine emissions. These devices basically spray the gases with water to eliminate harmful pollutants. You can also control them with dry processes such as fabric filters that have been coated with lime. This lime can be used as a raw material to make future tiles.

The tile industry is developing new processes to recycle the wastewater and sludge generated during milling, glazing, and spray drying. Some plants already recycle excess powder from dry-pressing and the glaze overspray. Recycled glaze and tile can also be returned to the body preparation for reuse.

Quality Control

Most tile producers now use statistical process control (SPC), which is used for every step of the manufacturing process. To ensure the materials are manufactured to specifications, many tile manufacturers work closely with raw material suppliers. The statistical process control charts are used to monitor different processing parameters such as particle size and milling time, drying time and time, compaction pressure and dimensions after pressing, density and firing temperature and times, and so on. These charts help identify equipment problems and out-of-spec conditions. They also improve product yields.

Specifications regarding chemical and physical properties must be met by the final product. The American Society of Testing and Materials (ASTM) has established standards for determining these properties. These properties include mechanical strength, abrasion resistance, and chemical resistance. They are also measured for water absorption, dimensional stability, and the linear coefficient of thermal expansion. Recently, slip resistance has been a primary concern. This can be measured by measuring the coefficients of friction. There is no set standard yet because there are other factors, such as floor design and maintenance, that can render results meaningless.

The Future

Tile manufacturers will continue to promote new products in order to sustain market growth. These include modular or cladding tiles, larger-sized tiles, slip- or abrasion-resistant tiles, and tiles with polished, granite, or marble finishes. This is possible through the development and application of new glazes and body formulations as well as further processing equipment and techniques. In order to increase production, reduce costs and improve quality, automation will play an important part. Changes in production technology caused by environmental and energy resource problems will also continue.

Professional marketing executive at Skytouch Ceramic, the top porcelai vitrified tiles company. Managing all the responsibility as a senior level.