Three Roll Mill: Grinding & Dispersing

Three roll mill is the most effective equipment for grinding and dispersing high viscosity materials. Three roll mills can be divided into lab three roll mills and production-type three roll mills. Mainly used in the production of paint, ink, pigment, plastic, and another slurry. Its working principle is to achieve the grinding effect through the surface extrusion of three horizontal rollers and friction at different speeds.

The three roll mill is an efficient grinding and dispersing equipment for high-viscosity materials. Particularly suitable for grinding products with high dispersion viscosity, fine particle size, and difficult to recycle materials or non-recycled materials in sand mills. High-power three roll mills are used for batch production, and low-power three roll mills are used for small batches or laboratories.

Features of three roll mill

1. The roles of the three roll mill are made of chilled cast iron by centrifugal casting, and the surface hardness is greater than HS70°. It is a high-strength, high-wear-resistant grinder whose toughness is not affected by external pressure and temperature.

2. After the rollers of the three roll mill are ground with high precision, the diameter of the rollers is small, which can make the grinding fineness of the material less than 5μm, and can produce uniform and fine high-quality products.

3. The transmission system of the three-roller grinder adopts a multi-row sprocket soft start, which has high transmission efficiency, stable operation, and no noise.

4. By adjusting the flat hand wheel screw to adjust the gap between the rollers, the granularity of the ground material can be adjusted, and the operation is simple, accurate, and convenient.

5. The three roll mill is equipped with a cooling device, which can dissipate the heat generated by the work of the rolls and ensure the continuity of the work. It works in many different colors and is easy to change colors.

Minimum set-up spacing for three roll mills

The distance between the rolls can be 0, but in practice, there must be a gap between the rolls to ensure that the processed material can pass between the rolls smoothly. In addition, if the roll spacing is 0 or too small, if the rolls are not cooled in time during the working process, they will be thermally expanded and the rolls will contact each other, which is likely to damage the rolls. Therefore, the size of the roll gap is usually recommended to be set at about  25 μm. The three roll mill relies on the huge shear force between the rolls to squeeze and rub each other to achieve the required fineness and grinding effect. The size of the roll gap is not equal to the final fineness requirement.

3 features of the three roll mill

1. The three-roller grinder has three rollers installed on the iron frame, and the center is in a straight line. It can be installed horizontally or slightly inclined. The grinding effect is achieved by squeezing the surfaces of the three horizontal rollers and friction at different speeds. Steel drums can be hollow and can be cooled with water. Add material between the middle and rear rolls. Since the rotation directions of the three drums are different (the rotation speed increases sequentially from the back to the front), a good grinding effect is produced. After grinding, the material is scraped off by knives mounted in front of the front rollers.

2. When using the three roll mill, check whether the position and locking of each part are normal. Add lubricating oil as shown in the figure, turn on the power, adjust the front and rear handwheels, observe whether the roller system is normal, and remove the dirt on the roller surface: wipe with soft paper or clean cotton yarn, loosen the baffle clamp, and adjust the front and rear rollers and the middle roller to 0.5 mm, then start the power supply and let it idle for 1-2 minutes.

3. The three roll mill is mainly used for various high-grade pastes, such as paints, inks, plastics, pigments, cosmetics, electronic pastes, solar silver pastes, aluminum pastes, glass solder pastes, etc. It is especially suitable for the grinding of products with high dispersion viscosity and high particle size required by the centrifugal casting of chilled gold cast iron rolls. The crystal phase is dense, the strength is high, the surface hardness is high, and the wear resistance is good.

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