Injection mold The idea and setting method of pressure preservation in injection molding

Injection molding pressure holding process is used to compensate for the reduction of resin volume as cooling proceeds. Fill at filling speed to 85 ~ 95%, then switch to pressure holding. Excessive pressure preservation will lead to overfilling, burr or deformation, poor release. It is usually set to maintain pressure at 2 levels.

Injection moulds Defects in the pressure retaining process of injection molding

Injection molding injection molding pressure is low, easy to appear shrinkage marks, pores and size is too small; When the retaining pressure is high, it is easy to burr, overfill and oversized size.

Injection molding method for setting up pressure retention in injection molding

Pressure holding time: The total pressure holding time is usually based on the gate sealing time of the product. Visually inspect the "indentation" status of the product and apply an acceptable level of pressure retention for a short time. As the pressure holding time gradually increases, the weight of the product will also increase proportionally. After a certain amount of time, the weight of the product is stable.

Note: Gate sealing time will vary greatly due to mold temperature and resin residence time in the screw, so please sample in the continuous forming process; If the filling speed and retaining pressure, which are the interim standards, change, the gate sealing time will also change.

Holding pressure: After determining the total holding time, set the pressure. Visually observe the appearance of shrinkage marks, burrs and so on, while gradually increasing the pressure preservation. As a conventional method to determine the retaining pressure, it is to find the "lower limit" and "upper limit" of the retaining pressure, and take other intermediate values as reference values.

Injection mold injection molding experience

The retention time and retention pressure Settings are also as simple as possible. Due to the uneven wall thickness and poor mold accuracy of the injection mold design stage, it is often difficult to manufacture products that can meet customer requirements only by relying on the setting of molding conditions.

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