Advantages and disadvantages of internal mixer and open mixer for plastic mixing
The ability of rubber to deform under external forces and maintain its deformation even after the external forces are eliminated is called plasticity. The process of increasing the plasticity of rubber is called plasticization. Rubber has plasticity in order to mix evenly with various additives during mixing; Easy to penetrate into textile fabrics during rolling processing; It has good fluidity during extrusion and injection. In addition, molding can also make the properties of rubber uniform, making it easy to control the production process. However, transition molding can reduce the strength, elasticity, wear resistance and other properties of vulcanized rubber, so the molding operation needs to be strictly controlled. Rubber plasticity is usually expressed in terms of William's plasticity, Mooney viscosity, and Deval hardness.
1. Open the mixer for molding
Its advantages are good quality of plastic compound, small shrinkage, but low production efficiency and high labor intensity. This method is suitable for factories with frequent changes in rubber materials and low rubber consumption. The opening mill belongs to low-temperature molding. Therefore, reducing the rubber temperature to increase the force is the key to opening the mixer for plastic mixing. The equipment characteristics and process conditions related to temperature and mechanical action are important factors that affect the plasticizing effect.
2. Internal mixer molding (high temperature, intermittent)
The internal mixer has a large production capacity, low labor intensity, and low power consumption; However, due to its closed system, it is difficult to clean, so it is only suitable for occasions where there are few changes in the adhesive type. The internal mixer has a complex structure. On the one hand, the raw rubber in the internal mixer chamber is subject to Shear stress and friction between the rotor and the cavity wall, on the other hand, it is also subject to the external pressure of the top bolt.