Extruded bricks are made by forcing clay through a die to create a continuous shape, which is then cut into individual bricks.
Here's a breakdown of the extrusion process:
- Clay Preparation: The process begins with preparing the clay mixture. This involves grinding, crushing, and screening the clay to achieve the desired consistency and remove impurities.
- Vacuum Extrusion: The prepared clay is then fed into a vacuum chamber. Removing air from the clay mixture improves its workability, strength, and reduces the likelihood of air pockets within the brick.
- Extrusion: The de-aired clay is forced through an extrusion die. The die's shape determines the cross-sectional shape of the continuous column of clay. This is the key step in giving the brick its basic form.
- Wire Cutting: As the column of clay emerges from the die, it is cut into individual bricks using a series of wires. The spacing of the wires determines the length of the bricks.
- Drying: The freshly cut bricks, known as green bricks, contain a significant amount of moisture. They are carefully dried to remove excess water, preventing cracking and shrinkage during firing.
- Firing: Finally, the dried bricks are fired in a kiln at high temperatures. This process vitrifies the clay, hardening it and giving the brick its final strength, durability, and color.
Compared to other brick-making methods, such as soft mud molding, extrusion uses a stiffer clay mixture with less water. This results in a denser, more uniform brick with sharper edges and a smoother surface.
