Injection Molding Learning

- Dec 19, 2018-

4. Plasticization capacity estimate

To determine if the product can maintain high quality throughout the production process, a simple formula for yield and plasticizing capacity can be used, as follows: t = (total injection shot g X3600) ÷ (plastic injection molding machine kg/h X 1000)

t is the lowest cycle time. If the cycle time of the mold is lower than the t value, the injection molding machine cannot fully plasticize the plastic to achieve a uniform melt viscosity, so the injection molded parts often have deviations. In particular, when paying attention to the quality of injection molded thin walls or precision tolerances, the amount of shot and the amount of plasticization must match each other.

5. Shooting tank retention time

The decomposition of plastic is based on temperature and time. For example, a plastic will decompose after being exposed to high temperatures for a period of time; however, in a lower temperature environment, it will take longer to decompose. Therefore, the residence time of plastic in the shooting tank is very important.

The actual residence time can be determined experimentally. The method is to measure the time required for the colored plastic to pass through the shooting tank. The following formula can be roughly calculated: t=(the nominal volume of the shooting tank g X cycle time S)÷ Quantity g X300)

It is worth noting that some plastics have a longer residence time in the shooting tank than is required for calculation because they can coalesce in the shooting tank.