The main factors affecting the plasticizing quality are […]
The main factors affecting the plasticizing quality are: aspect ratio, compression ratio, back pressure, screw speed, barrel heating temperature, etc.
1. Length-to-diameter ratio: the ratio of the effective working length of the screw to the diameter of the screw.
2. Compression ratio: it is the ratio of the depth of the last screw groove of the feeding section to the depth of the first screw groove of the metering section.
3. Back pressure, increasing the back pressure can increase the work done by the screw on the molten resin, eliminate unmelted plastic particles, and increase the density and uniformity of the raw materials in the barrel; back pressure is used to increase the barrel temperature, and its effect is the most significant ; If the back pressure is too large, the plastic with high heat sensitivity is easy to decompose, and the plastic with low viscosity may cause salivation. If the back pressure is too small, the injection molded product may have bubbles.
4. The screw speed and the screw rotation speed directly affect the shearing of the plastic in the spiral groove; the small screw groove is shallow and absorbs the heat source quickly, which is enough to promote the softening of the plastic during the compression period, and the frictional heat energy between the screw and the barrel wall is low. It is suitable for high-speed rotation and increases the plasticizing capacity. Large-scale screws are not suitable for rapid rotation, so as to avoid uneven plasticization and excessive frictional heat.
5. The electric heating temperature is set to melt the cold and hard plastics remaining in the barrel and the screw to facilitate the rotation of the screw, and provide a part of the heat required for the melting of the plastic.
