Ceramic tile production process
Ceramic tile production process
Ceramic tile production process – In general, there are currently two methods for making ceramic tile products in the world, the difference between which is the method of drying and baking tiles. In the first type, it is double firing. In this method, after drying the tiles in the dryer, the tiles are baked once under high heat in the oven and then glaze is added to it and then It goes into the oven for re-cooking.
In the second method, called single firing, the first baking process is removed and the tile is soaked in glaze after drying in the dryer and then sent to the baking oven. In the second method, the firing operation is faster than the first method, but in the two-flame firing method, the flexibility of the tiles is greater. This is so important that many tile manufacturers use the double fire method.
Description of the production process of ceramic tiles
Preparation of raw materials
Usually for the production of tiles from various minerals and soils such as clay, feldspar, silica, kaolin, barium carbonate, and by-products such as sodium silicate, a variety of paints, to reduce production costs are usually mines and raw materials Factories are close by.
Per grinding of hard raw materials:
The mentioned raw materials are mainly received in the form of stones, soil and lumps from the mines and in this unit, which mainly includes crusher, ball mill, iron separator and و, they are crushed and granulated. Due to pollution and dust, this unit is preferably away from the production hall and in a place outside the factory. The crushed material is loaded by the loader and transferred to the silos of the material warehouse.
Batching and mill feeding:
All materials are carefully weighed so that the product is preserved, so it is essential to use an accurate measure of the amount of weighing.
Continuous mill feeding:
Raw materials sent to silos, daily, along with water, lubricants and other additives stored in tanks. They are weighed in certain proportions and transferred to a continuous mill.
Due to the fact that there are different types of raw materials here, mixing and crushing of these materials must be done in special mills (mainly ball). Grinding in order to achieve a homogeneous mixture is usually done up to 63 microns. Upon entering the continuous mill, the materials mentioned in the feed section of the mills enter the mill so that the material crushing process can be done in a wetter way (in a ball mill with ceramic balls). The uniform slurry obtained from this operation after passing It is transferred from special sieves to storage ponds.
A ball mill or ball mill is made of a cylinder in which ceramic pellets are made that are very resistant to abrasion. If these balls are not made of resistant material, they will be crushed and mixed with raw materials and the composition of materials will be different. The cylinder is rotated at a constant speed by an electric motor connected to a gearbox. This rotation causes the bullets to roll on top of each other, causing the raw materials to crumble and become one-handed.
Therefore, the composition of the mill and the bullets are chosen in such a way that in case of wear and its entry into the composition, it does not have much effect on the formula. The amount of charge in the material and pellets in the ball mill should be such that, firstly, the pellets create a uniform surface and, secondly, the surface of the bullets occupies half the volume of the balloon.
In case of spillage, the water and material should cover the volume of the balloon and the rest of the balloon should be empty so that the material can rotate easily. In this case, the contact surface of the bullets and the ball is as high as possible.
There are two types of ball mills:
It can be acknowledged in the operation of the ballm discontinuities, the raw materials are poured together with the abrasion balls and the size and capacity of the ballmill is poured into it and the ballmill starts to rotate until the mill is fully finished and then It stops and the abrasive material comes out of it and this operation is repeated again.
Regarding the performance of continuous balloons, it can be briefly stated that in this type of balloons, the raw materials enter the balloon from one side and leave after grinding from the other side, and there is no need to stop the balloon to charge the material.
Continuous ball mill mechanical equipment
In addition to mechanical equipment, Balmil needs other equipment, which can be briefly mentioned as follows:
1. Raw material weighing equipment: Raw materials enter the silos and go to the balm by conveyor belt. If the wear is not dry, lubricant and water should be added to the balm by pumps.
2. Control system: To start, stop, accurately measure the amount of water and raw materials, as well as direct and control the output materials, we need a precise control system that includes a variety of sensors and PLC and a software implementation program in its structure. it is needed.
3. Separators: The most common type of separators that can be used in CCTV ballasts and are located at the outlet are silicone separators and sieves.
Balmil body structure
Shell: To prevent wear, the shell inside is covered with liners and the liner is screwed to the body. At the time of design, a place should be considered for installing the ball gear on the body.
Caps: The caps used pass through the bearings at both ends of the ball on one side and are screwed to the shell on the other side. The weight of the shell and the contents of the ball are transferred to the bearings through these caps. In ball mills, two types of sliding and rolling bearings are used. In discontinuous ball mills, sliding bearings are used because they are cheap and in continuous ball bearings, roller bearings are used which have high prices.
Power transmission in ball mills:
Ballmills use two methods to transmit power:
Belts and pulleys: In this type of transmission system, power is transferred to the ballmill by belts and pulleys from the engine or gearbox. This transmission system is used in discontinuous balloons due to cost reduction and economic discussion, which are also less efficient.
Gears and pinions: In this type of system, which is used in continuous ballmills, the movement and transfer of power is done through the pinion from the gearbox to the gears that are installed on the body of the ballmills.
Power transmission methods:
Via gearbox: Power transmission is transmitted to a gear or pinion via a gearbox. This method is one of the most widely used methods of power transmission, which can be used with hydro coupling to reduce the torque of the driver. Some gearboxes are equipped with an auxiliary system that rotates the balm in certain conditions with a low power motor and high conversion ratio.
Direct power transmission: In this method, the low speed motor is connected directly to the pinion or gear, this method takes up less space and can be used during start-up through hydro coupling to reduce torque.
Belt and pulley power transmission: In this type of system, which is usually used in discontinuous balloons due to cost reduction, the electric motor speed is reduced in two stages, first by one belt and pulley, and in the second stage by another belt and pulley. It quickly becomes the name of the ballmill.
The motors used in power transmission systems in balloons are usually AC. In special cases, diesel engines are also used.
Preparation of powder
To prepare the powder from the slurry, spray dryers or sprayers or spray dryers are used. The slurry from the mills enters the slurry tanks after spraying in the slurry tanks, which causes the homogeneity of the slurry and improves its plasticity. Piston pumps with relatively high pressure pump the slurry into a cylindrical spray dryer chamber which is hot and the slurry after contact with hot air and water evaporation turns into a powder with a certain moisture and granulation. After passing through the cyclones and dusting, the chamber air and water vapor are released from the spray dryer outlet and its product, which is powder, is poured on the conveyor belt from under the sheath and stored in the powder silos.
The quality of the powder depends on the following factors:
Slurry quality, body formula and especially its plasticity, density, viscosity and granulation of the slurry
Spray dryer type
– Type of sprayer nozzles and the number and size of holes and their arrangement
– Material of nozzles and other nozzle components
– Dimensions of the chamber
– Pumping quality and pump pressure
– Powder moisture and powder granulation
– Powder strength and homogeneity of their moisture
– Durability of the powder
– Heat inside the chamber, pressure inside the chamber and humidity of the chamber
– Gas pressure stability
– Proper selection of the type and pressure of pumps are important in this process because it improves the particles of materials used in the production of tiles.
After preparing the raw materials in powder form, they turn it into a tile body by pressure, which is called biscuit preparation. In cases where the amount of water in the body powder (granules) is more than about 4%, the so-called semi-dry press or synonymous with powder press is used. In cases where the amount of water in the body powder is less than 4%, the term dry press is used.
In the tile industry, two types of presses are used:
– Mechanical or impact presses
-Hydraulic presses that use a hydraulic system. Where hydraulic energy causes deformation.
Today, the presses selected for the tile production process are mostly hydraulic presses; The advantages of these presses are as follows:
– Less maintenance
– Relatively less wear of parts
– Easy to build
– long life
dryer Ceramic tile production process
The prepared biscuit goes into the dryer, this process reduces the water in the raw biscuit to less than 1% and prepares it for baking. New vertical dryers have been able to reduce the problem of prolonged drying in older tunnel dryers, which sometimes takes several days, to the shortest possible time, about 20 minutes or less.
The waste in tunnel dryers, which showed itself as cracks and fractures, sometimes went up a lot for various reasons, and other problems due to the porcelain system of raw tiles (stacking tiles), the effect of bumps on the back of the tile on It was painted on the surface of the lower tiles and after glazing and baking, it was completely visible on the glazed surface, while these problems have been almost eliminated in the new drying system.
Cooking Ceramic tile production process
In old tunnel kilns, it takes 48 hours to bake biscuits and 12 hours to bake glaze. But the new generation of ovens that were introduced to the market in 1997 were fast baking ovens, which are also called roller ovens because in these ovens there are rollers on which biscuits are placed and move into the oven. کردن. These refractory rollers are made of alumina to have a high reception shock.
The entrance rollers are also made of metal with rubber coating, the tiles enter the furnace row by row. The baking cycle of biscuits is 30 minutes and the glaze baking cycle is 35 minutes.
Engraving and glazing:
The next step is to apply engobe and then glaze on the biscuits.
Angob Ceramic tile production process
Angob is a coating that is applied to cover the surface of the body before applying the paint. This operation is done when the body has lost some of its water but has not yet dried completely. Wet shrinkage of the dry part of the ingobs as well as the firing temperature of the ingobs should be between the body and the glaze. Angoob is longer than the body and prevents the tile from coming into direct contact with the rollers so that it does not become contaminated quickly. In the case of wet-to-dry shrinkage, the best situation is when the shrinkage is a little less than the shrinkage of the body, because shrimp is used when the body is somewhat dry.
Reasons to use Angoob Ceramic tile production process :
– Cover the body color
– More compatibility of the coefficient of thermal expansion of the body and the glaze
– Prevent the occurrence of defects (pin hole) and welding in the glaze, which is caused by annoying reactions
– Water absorber regulator of tile body
– Increased adhesion of raw glaze to the body
– Modifier of warping resulting from the interaction of the glaze and the body, especially in the technique of two quick cooking
Glazing for ceramic tiles:
Glaze is a thin layer of glass that covers the surfaces of the ceramic body and is formed by melting minerals on the surface of the body. Glaze always becomes pasty and molten at a lower temperature than ceramic bodies, ie they have fewer dough points. In the production of floor and wall tiles, the purpose of covering the surface of the biscuits with glaze is mainly to beautify the products, increase their chemical and mechanical resistance, make the porous bodies impermeable and make the surfaces of the products hygienic. Increases its density, hardness, polish and color, and makes it strong and stable against chemical agents.
Glaze optimizes ceramic objects in terms of the penetration of liquids and gases into the tissue as well as density, thus reducing corrosion and other adverse factors.
Common methods of producing ceramic glazes and tiles:
– Production by rotary kilns (Batch)
– Production of glaze by Continous furnaces
– The body of the furnace, which includes a cylinder of metal and two cones on either side of it horizontally.
– Torch that ignites the fuel and sends it into the furnace space.
– A fan that supplies air to ignite fuel in the furnace.
– Rollers on which the furnace moves in a circular motion.
– Electric motor that provides the necessary force to rotate the furnace.
– Furnace charging and discharging valves
– Furnace bases
Continuus Furnace production process :
This method is used for melting fixed furnaces. After mixing and formulating, the material enters the furnace and is charged by screw pressure. The inside of the furnace is rectangular in shape, in which the thermal resistance is very high, and by a number of burners on both sides, the material melts little by little The other one comes out and when the molten material leaves, it enters the cold water and is poured out of the pond by the vibrating tape and poured into the bags.
Baking and testing of ceramic tiles production process:
After glazing and to stabilize it, ceramic tiles are baked, and this causes the tile and glaze to melt on the surface and is done transparently in the oven. The glaze oven does this. The temperature of the glaze oven is lower than the temperature of the biscuit oven, from 1000 to 1040 degrees, and it takes about 5 to 35 minutes for the tile to come out of the oven.
The characteristics of the oven are the same as baking biscuits, and the only difference is in the temperature and baking time.
After the kiln, the tile testers are tested for strength (bending, resilience) immediately after leaving the kiln. In the strength test, the wheel puts a certain pressure on the tile. If there is a crack or Mac tile, the tile breaks and goes out of line.
After this step, the tiles move to the grading area. Along the way, there is a device called a storage or buffer that, if done in the packaging or grading section, the tiles are stored by a buffer.
Grading and sorting production process :
During baking, there may be many defects and defects for the glaze. It is necessary for the tiles to be graded in terms of appearance quality before packing. In general, the tiles are graded based on the appearance of the surface, resilience and size. This operation is graded by the operators based on the defects in the tiles such as (paleness, cracks, color, print quality, back glaze, welding, etc.). The operator adjusts the degree of the tiles by hand or by magic. In the usual production line, the tiles are divided into 5 grades, of which grades 1, 2, 3 are available in the market, and 4 and 5 are stock and out of date.
Grouping Ceramic production
After this part, the tile is transferred to the sorting section, in this section, two infrared sensors read the mark on the tile and direct them to the stickers. In this section, there are a number of stickers that separate the tiles with different grades. The tiles of the same symbol are arranged and stacked on top of each other by the stickers. The number of tiles stacked on top of each other is determined by the area and it is tried that each batch of ceramic tiles is one square meter. On the shoreline, where the size of the tiles is 25 x 40, the tiles are stacked in 10 pieces and directed to the packing section.
packing production process
In this part, the separated tiles are transferred for cartoning. In the packing machine, the tiles are arranged in several rows by several arms in a row, then the cartridges are inserted into the inlet machine by the air suction device, and they are placed around the tiles and glued. The cartons are removed after the shearing machine and each carton is placed on a pallet based on the degree eaten and the nylon is wrapped around it with a rotary machine. The pallets are sent to the warehouse by forklifts and are ready for distribution.
Equipment used in the production of production process:
– Weighing system
– Balmil slurry
– Slurry dryer
– Nutrition of Zakmi press
– Vertical dryer
– Vibrating sieves
– LB equipment
– Horizontal dryer
– Enamel drainage tanks
– Enamel line tanks
– Dust collector
– Enamel line
– Rollerbox moving device
– Loading and unloading
– Color router printing machine
– Roller box
– Polishing line
– Polished water purification system
– Sort line
– Pallet packing line
– Palletizer machine
– Packing line
– oil filter
– Torch and pot
– Balm for preparing glaze
– air filter
– Pre-crushing equipment
Part of the special equipment used in the production of ceramic tiles:
1. Spray dryer and furnace equipment, switch switch, burner controller, burner gas controller, valve controller, flame detector and eye, spare lamp, servomotor and damper, ignition relay and transformer, gas filter and regulator, temperature and pressure controller, Thermostat, evaporator, Shut Off regulator valve, solenoid and gas valve, thermometer, ion and ignition electrode
2. Thermocouple, furnace pressure manometer, roll stone diamond
3. Materials preparation, glazing and laboratory equipment including: vibrating sieve and sieve, diaphragm and piston pumps, vibrating motor
4. Float pumps and valves and spare diaphragms, spray flanges and spiral and screw nozzles, all kinds of fuse nozzles
5. Types of magnet rollers and separators. Roto Color Blade
6. Positioner and butterfly valve. Pressure, temperature and flow sensors
7. Densimeter, flowmeter, viscometer, magnetic shaker
8. Online humidity sensor of granules and powder with the ability to be installed on the conveyor and feeder valve of silos with a graphic display. Portable hygrometer and thermometer
9. Italian Industrial UPS High Power Online for Emergency Spray Dryer Furnace with Minimum Line Stop Time
10. Level and level meter sensor
11. Accessories for hot packing adhesive machine including: hose, pump, brass filter, etc.
12. Piston and diaphragm pumps
13. Laser (optical) camera length of the furnace and digital manometer
14. Hydraulic press valves with warranty
15. Hpc cards and Xsub digital printing processor
16. Press, furnace and packaging cards
17. Temperature controllers, furnaces and dryers
18. Types of inverters
19. Pneumatic equipment (cylinder, valve, pump, jack, etc.)
20. Nuovafima and PowerPac stepper motors and packing drives