1. The mud is required to have an appropriate and stable particle composition

When pressing bricks, if there are too many coarse particles in the mud, the corners of the bricks will be loose. The surface is rough and the particles fall off; if the mud material is too fine, the air film (or water film) in the mud material is large and the elastic aftereffect is large during pressing, which can easily cause cracks.

2. Pressure and moisture must be compatible

The moisture in the mud material mainly plays a binding and lubricating role, which is conducive to the movement between particles of the mud material under the action of molding pressure. When the mud material with lower moisture content is molded, the internal friction is larger. To obtain a dense body, a higher molding pressure is necessary. However, high-pressure molding cannot be used for mud materials with high moisture content, because the elastic aftereffects of high-moisture mud materials are large when molded, and water is easy to concentrate in non-dense parts of the body, so over-pressure cracks are prone to occur when molded with high pressure.

In general, molding pressure and mud moisture content requirements are inversely proportional. For example, for clay products, when low-pressure molding (manual molding) is used, the moisture content of the clay material is generally 8 to 9%; when high-pressure molding (machine molding) is used, the moisture content should be lower, generally 3 to 5%.

3. Molding operation

When molding the friction brick press, the initial pressure should be light and slow, which is conducive to the elimination of air in the mud. If the initial pressure is too heavy and too fast, the surface layer will be compacted and the air cannot escape, which will easily produce excessive elasticity and cause damage. The bricks are cracked. Therefore, the principle of pressing bricks first and then heavier is adopted in current production.

related tags: Insulating Fire Brick, Refractory Bricks