What are the factors that affect the fluidity of plastics?

Most of the plastic molding processing is realized by the deformation and flow of the plastic in the viscous flow state. The fluidity of plastic is an index to measure the difficulty of plastic molding and processing. So what are the factors that affect the fluidity of plastics?

The fluidity of various plastics also changes due to various molding factors, and the main influencing factors are as follows:

1. High material temperature increases fluidity, but different plastics have their own differences. PS (especially those with high impact resistance and higher MFR value), PP, PA, PMMA, modified polystyrene (such as ABS, AS ), the fluidity of PC, CA and other plastics varies greatly with temperature. For PE and POM, the temperature increase or decrease has little effect on their fluidity. Therefore, the former should adjust the temperature during molding to control fluidity.

2. As the pressure of injection molding increases, the molten material is subjected to greater shearing and fluidity, especially PE and POM are more sensitive, so the injection pressure should be adjusted to control fluidity during molding.

3. The form, size, layout, cooling system design of the mold structure, the flow resistance of the molten material (such as the surface finish, the thickness of the channel section, the shape of the cavity, the exhaust system) and other factors directly affect the molding of the molten material. The actual fluidity in the cavity will reduce the fluidity if it causes the molten material to lower the temperature and increase the fluidity resistance. When designing the mold, a reasonable structure should be selected according to the fluidity of the plastic used.

Note: When designing the mold, a reasonable structure should be designed according to the fluidity of the plastic used. During molding, the material temperature, mold temperature, injection pressure, injection speed and other factors can also be controlled to appropriately adjust the filling condition to meet the molding needs of the part.