Plastic shrinkage is the percentage of the difference between the size of the plastic part at the molding temperature and the size removed from the mold after cooling to room temperature.
Effect of Molding Process on Shrinkage of Plastic Products
(1) the same molding temperature, injection pressure increases, shrinkage decreases;
(2) to maintain the pressure increases, shrinkage decreases;
(3) melt temperature increased, shrinkage decreased;
(4) mold temperature is high, shrinkage increases;
(5) holding time is long, shrinkage decreases, but the gate closed does not affect the shrinkage rate;
(6) the mold cooling time is long, the shrinkage decreases;
(7) injection speed is high, shrinkage slightly increased tendency, less impact;
(8) forming shrinkage, after the shrinkage is small. After the contraction at the beginning of two days, a week or so stable. Plunger injection molding machine shrinkage.