Analysis and countermeasure of residual stress of injection mould products

The residual stress of injection mold refers to the compression stress and tensile stress residual in the injection molding process, which may gradually release over time, resulting in the damage of the injection molding product such as warping, deformation or cracking.

There are various opinions on the causes of residual stress in injection mold products, and there is no clear conclusion at present. There are four mainstream theories as follows.

1. The pressure is not balanced in the injection molding process, especially the residual stress caused by the uneven pressure near the gate and the thin wall part;

2. In the process of injection molding, the thick wall part is pulled by the thin wall part which is cooled first, resulting in residual stress;

3. When the resin flows in the injection mold, it orients, resulting in uneven internal shrinkage and residual stress of the molded product;

4. When injection molding products are demoulded, the residual stress is caused by uneven top force.

How to deal with the residual stress of injection mould products?

1. In the design of injection mold using a reasonable structure, in-depth discussion on how to minimize the residual stress of molding products, of course, this requires long-term experience summary and accumulation;

2. For some high requirements can not withstand the damage caused by residual stress deformation of injection molding products can be used annealing treatment measures, before the use of the molding product deformation, to avoid its use in the process of change with the passage of time.

3. Using product post-treatment to reduce the internal stress of injection molded products to the minimum range, usually using a circulating air drying oven after heating natural slow cooling to room temperature, so that the molecules produce a certain degree of relaxation to reduce the residual stress in the products.

In the process of injection molding, the injection speed can be properly improved and the pressure holding pressure can be reduced to reduce the deformation and damage caused by residual stress. The mission of Fanstar is to master the core technology of injection molding production, communicate and analyze the technology before mold production with customers from the production needs of finished products, so that the mold delivery time is short, the service life is long, the rapid mass production and the finished product quality is excellent! Have the need of injection mold welcome to contact us!