Introduction to Tile Manufacturing
The manufacture of clay tiles is an age-old process that blends traditional craftsmanship with modern techniques to create durable, versatile materials widely used in construction. From roofing to flooring, clay tiles provide a natural aesthetic and lasting durability. The process of manufacturing tiles requires precise handling of raw materials to ensure consistent quality and strength. Key stages in the tile manufacturing process include the preparation of clay, shaping and molding, drying, and burning to achieve the desired hardness and finish. Here, we’ll explore each step in detail, from refining raw clay to producing high-quality tiles ready for building projects.
The manufacture of clay tiles is an age-old process that blends traditional craftsmanship with modern techniques to create durable, versatile materials widely used in construction. From roofing to flooring, clay tiles provide a natural aesthetic and lasting durability. The process of manufacturing tiles requires precise handling of raw materials to ensure consistent quality and strength. Key stages in the tile manufacturing process include the preparation of clay, shaping and molding, drying, and burning to achieve the desired hardness and finish. Here, we’ll explore each step in detail, from refining raw clay to producing high-quality tiles ready for building projects.
Manufacture of Tiles
The process of making standard clay tiles involves four primary stages:
- Preparation of Clay
- Molding of Tiles
- Drying of Tiles
- Burning of Tiles
1. Preparation of Clay
To produce high-quality tiles, the clay must be carefully prepared. The finest blue clay, often located beneath the layer of brick earth, is selected for its suitability. This raw clay is first cleansed of impurities like grit and pebbles to ensure smoothness and consistency. The cleaned clay is then crushed into a fine powder using crushing roller mills, after which it undergoes pugging to improve its plasticity.
For premium tile production, an additional refinement process is carried out. The powdered clay is mixed with water in a settling tank, allowing heavier particles to sink. The fine clay particles, suspended in the water, are transferred to a secondary tank where they are left to dry, producing a high-grade clay paste ready for molding. This process of refinement enhances the clay’s texture and purity, essential for creating superior-quality tiles.
2. Molding of Tiles
The method chosen for molding tiles depends on the desired shape and pattern of the final product. Each molding technique is suited to a specific type of tile, ensuring consistency in shape and durability.
For tiles with uneven thickness or intricate patterns, wooden molds are commonly used. The pugged clay is carefully pressed into these wooden molds to achieve the desired shape. Once molded, the tiles are gently removed and set aside for the drying process.
In cases where tiles are circular in shape, a potter’s wheel may be utilized. However, this method may result in variations in diameter along the tile’s length, which is taken into consideration during the molding.
For tiles requiring a uniform thickness and cross-section throughout, a mechanical extrusion method is often employed. Here, the prepared clay is forced through a die or orifice with the specified shape and size. As the clay emerges in a continuous beam, it is placed on a receiving platform, where wire frames cut it into tiles of the desired length. This mechanical approach allows for efficient production of tiles with consistent dimensions.
3. Drying of Tiles
After the tiles are molded, they undergo a preliminary drying phase. Approximately two days after molding, each tile is gently tapped with a flat wooden mallet to correct any shape irregularities caused by warping. This careful beating helps maintain the tile’s intended form and smoothens any surface inconsistencies.
Following this, the tiles are placed upright on their edges and left to dry under shaded conditions for another two days. This gradual drying process minimizes the risk of warping and cracking, allowing the tiles to retain their structural integrity and shape before moving on to the final stage of production.
4. Burning of Tiles
Burning is the final and most critical stage in tile manufacturing, where the tiles gain their strength and durability. This process takes place in large kilns, capable of holding 30,000–40,000 tiles, which are typically built partially underground and equipped with a roof to shield against rain.
The kiln’s base consists of long, narrow flues that allow for the controlled movement of heat. A layer of bricks is carefully arranged over these flues, leaving small gaps to facilitate airflow. Above the brick layer, the dried tiles are stacked on edge, layer by layer, until the kiln is completely filled. Once fully loaded, the kiln’s doorways are sealed.
The firing process begins by heating the kiln to an initial temperature of around 800°C, which is maintained for six hours to start the slow heating process. The temperature is then raised to about 1,300°C for an additional three hours. Following this, the kiln is slaked (cooled slightly) for six hours before another cycle of steady heating for 3–4 hours. During these phases, fuel is regularly added to the flues, and finally, the kiln’s doorways are sealed with brick and mud.
After the final heating, the kiln is allowed to cool gradually over a period of 72 hours, ensuring the tiles cool evenly and do not crack. Once cooled, the tiles are carefully removed, completing the manufacturing process and resulting in high-quality, durable tiles ready for use.
