Injection molding is a common plastic processing method. Due to factors such as thermal expansion and contraction of materials, injection rate, injection temperature, and mold structure, injection molded products may experience shrinkage.

1、 In terms of plastic raw materials

Additives and color masterbatch in plastic raw materials also have a certain impact on shrinkage, especially color masterbatch. Due to the high density of color masterbatch, excessive use can lead to product shrinkage. For the selection of plastic raw materials, reference should be made to the plastic specifications and appropriate raw materials should be selected.

2、 In terms of injection molding process

1. Injection molding temperature too high or too low: Improper temperature control of the injection molding machine can cause the product temperature to be too high or too low, which can affect the thermal expansion and contraction of the material, leading to shrinkage of the product. The correct approach is to adjust the injection temperature according to the plastic specifications and control it within an appropriate range.

2. Injection rate too fast or too slow: An injection rate that is too fast can cause the material to experience excessive shear force during molding, resulting in excessive thermal deformation; A slow injection rate can cause the plastic to cool too quickly inside, thereby affecting the dimensional stability of the product. Choose the appropriate injection rate based on the characteristics of the plastic and the shape of the mold.

3. Excessive or insufficient injection pressure: Injection pressure also has a significant impact on the dimensional stability of the product. Excessive injection pressure can cause unstable plastic flow, resulting in shrinkage and warping; However, if the injection pressure is too low, there will be a large number of bubbles and nodules in the product, which will affect the appearance and mechanical properties. Choose the appropriate pressure based on the shape of the mold and the characteristics of the material.

3、 In terms of plastic parts and mold structure

1. Uneven product wall thickness: Uneven product wall thickness can cause internal stress during the cooling process, leading to shrinkage. Ensure even wall thickness of the product.

2. Mold surface adhesion: The surface of the mold is not smooth or has burrs, which can cause plastic to be squeezed, pulled, and other phenomena when entering the mold, which can also affect the dimensional stability of the product. Adjustments and repairs should be made according to the surface of the mold.

In summary, to solve the problem of product shrinkage, it is necessary to comprehensively consider multiple aspects such as the selection of plastic raw materials, control of injection molding process, and adjustment of plastic parts and mold structure. As long as strict quality control and sound production processes are achieved, the occurrence of product shrinkage can be avoided, ensuring the quality and stability of the product.