How are porcelain tiles produced?
Most tiles today are porcelain tiles made with special clay, sand and minerals and fired at high temperature of 1200℃. This makes it more durable than other hard surface floors.
But how do we get tiles that replicate stone, wood or marble designs? Our product development engineers show you the processes involved in the diagram here.
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Porcelain tiles are made from very fine clay that is fired at high temperatures to remove moisture and to form a hard, and dense tile. The characteristics of porcelain tiles are dense and durable with water absorption of less than 0.5%. Porcelain tiles are vitrified tiles, wherein producing them, elements such as quartz, silica, or feldspar are added into the clay mixture. This results in less porosity and lower water absorption, making the tiles harder and can hold more strength.
Porcelain tiles have been crafted across the globe for thousands of years, they are widely used on floors and walls due to the low water absorption, sleek appearance and easy maintenance features that made them highly versatile.
Today, manufacturers around the world have changed the outlook and quality of porcelain tiles dramatically by updating the design, production methods and technologies in producing them. The high density of porcelain tile makes it ideal for medium to high traffic areas at residential and commercial space.
Step 1: Batching
For most ceramic products, the body composition is determined by the amount and type of raw materials. The raw materials determine the colour of the tile body, in the colour and hardness. Therefore, it is important to mix the right amounts to achieve the desired properties. Batch calculations are used to get the correct weight of each raw material to achieve the perfect combination of raw materials.
Step 2: Mixing & Grinding
Once all materials are ready, such as clay, feldspar, silica, sand etc. is then charged into a giant mixer, called ball mill. A known amount of water is added in during the mixing process. Ball stones or alumina pebbles are added into the ball mill to help the mixing process to grind the material into a finer particle. The result of this water-filled mixture is called slip.
Step 3: Colour Mixing
Ceramic pigments are added to the slip to obtain the various coloured bodies. Mixing is carried out in a high speed blunger tank. This process is omitted for a basic body with the natural body colour.
Step 4: Spray Drying
Excess water in the slip is removed via spray dryer. The process involves pumping the slip into an atomizer consisting of nozzles. Moisture of the slip droplets are dried as they are heated by rising hot air. The liquid slip will then turn into powder form.
Step 5: Creating the Tile
The next process tiles are formed by dry pressing the dried slip powder in a forming die. The material is compressed with at steel plunger at an extreme pressure of over 7,500 tons, which creates a pressing pressure of more than 400kg/cm². The objective of this process is to obtain a compact and less porous ceramic mass which in return resulting in a stronger body with extremely low water absorption after firing. The form body are called green tile.
Step 6: Drying
Prior to firing, the green tile goes through a drying process to further remove excess moisture at a slow rate and in a relatively high humidity atmosphere to prevent shrinkage cracks.
Step 7: Print & Glaze
After the green tiles are dried, the next step is to add printing and patterns with laser inkjet to cover the body colour and to obtain the required effect, colour and texture on the tiles. This step will also improve its resistance towards staining and to give the tile a distinctive design. A layer of glaze material is then applied on top to provide moisture resistant and decoration, as they can also be coloured or use to produce special texture.
Step 8: Firing
The next step is the firing of the tile at an extremely high temperature of 1200°C in a roller kiln. The high temperature will help set the glaze and remove the remaining moisture, transforming the soft clay into hard, durable and non-porous tile. Much like baking at home, different tile size will require different baking duration and heat.
Step 9: Polishing & Squaring
Lastly, most finished tiles are then sent for polishing. This process is where tiles are ground and polished to give their surface a nice glossy finish. With the different degree of polishing and the application of different abrasive tools, tiles can be polished to a glossy mirror finish or a lapato finish. Finished tiles can have their edges rectified or non-rectified. Rectification is generally called “squaring”, this is the process where the tiles’ edges are cut or ground to a uniform work size with very minor variation for the ease of installation.
Step 10: Selection & Packing
This is the final process before the tiles are being send out to you. All tiles are graded in accordance to the visual defects, flatness and dimensions, shades and size. They are then grouped and packed accordingly with proper labelling on the boxes.
