How to solve the shrinkage problem of injection molding processing?

Shrinkage problem is one of the common quality defects in the injection molding process, which directly affects the dimensional stability, appearance quality and mechanical properties of the product. To solve the problem of shrinkage, it is necessary to consider and adjust from the material selection, mold design, injection molding process and other aspects.

Material selection is the basis for solving the shrinkage problem. Different plastic materials have different shrinkage characteristics, so choosing the right material is crucial to controlling the stability of the product. For example, the use of filler materials can significantly reduce the shrinkage of plastics, but at the same time may affect other properties, such as fluidity, toughness and so on. Therefore, when selecting materials, the specific requirements of the product and the use of the environment should be fully considered to balance the performance indicators of the material.

Mold design plays a decisive role in controlling shrinkage. Reasonable mold design can ensure that the plastic shrinks uniformly during the cooling process and reduce the generation of internal stress. For example, by optimizing the location and size of the gate, the flow direction and speed of the molten rubber can be controlled, thus reducing local shrinkage. In addition, the reasonable setting of the cooling system, so that the temperature of all parts of the mold is uniform, is also the key to prevent shrinkage.

The adjustment of injection molding process parameters should not be ignored. Process parameters including injection pressure, injection speed, holding time, holding pressure, mold temperature and plastic temperature will affect the shrinkage behavior of plastic. For example, increasing the holding pressure and prolonging the holding time can increase the compactness of the plastic and reduce the shrinkage; while increasing the mold temperature and plastic temperature appropriately can improve the fluidity of the plastic and reduce the internal stress. However, there are interactions between these parameters and the best combination needs to be found through experimentation and experience.

In addition to the main measures mentioned above, there are some auxiliary means that can be used to solve the shrinkage problem. For example, post-processing techniques such as heat treatment and coating can improve the dimensional stability of the product to a certain extent. In addition, the use of advanced inspection technologies such as laser scanning and three-dimensional measurement can detect and solve shrinkage problems at an early stage to avoid large-scale scrapping in mass production.

In practice, solving shrinkage problems often requires multifaceted efforts. On the one hand, it is necessary to continuously accumulate experience and data to build up a complete solution library; on the other hand, it is necessary to focus on interdisciplinary communication and cooperation, and to learn from the successful experience and technology of other fields. Only in this way can we really solve the shrinkage problem fundamentally and improve the quality and efficiency of injection molding processing.