The main factors affecting the quality of plasticizatio […]
The main factors affecting the quality of plasticization 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.
a, the ratio of long diameter to diameter is easy to eat;
b. The plastic with better thermal stability can be used with a longer screw to improve the kneading property without scorching. The plastic with poor thermal stability can be used without a screw or a screw end. Considering the plastic characteristics, the general flow length is as follows: thermoset is 1416, hard PVC, high viscosity PU and other heat sensitivity is 1718, general plastic is 1822, PC, POM and other high temperature stability plastic is 2224.
2. Compression ratio: the ratio of the last groove depth of the feed section to the first groove depth of the metering section.
a. Considering the compressibility, filling degree, reflow, etc. of the material, the product should be dense, heat transfer and exhaust;
b. Appropriate compression ratio can increase the density of plastics, make the combination of molecules and molecules more tight, help to reduce the absorption of air, reduce the temperature rise caused by pressure, and affect the difference of output, improper compression Than will destroy the physical properties of the plastic;
c. The higher the compression ratio, the higher the temperature rise caused by the plastic in the plasticizing process of the plastic pipe, the better the mixing uniformity of the plastic in the plasticizing process, and the relative discharge amount is greatly reduced.
