How is Internal Stress Generated?

As an ABS Plastic Tube Core Supplier, let's talk about how internal stress is generated when molding a product.

In an injection molded article, the local stress state is different everywhere, and the degree of deformation of the product will be determined by the stress distribution. If the product is cooling. If there is a temperature gradient, such stress will develop, so this type of stress is also called "forming stress".

                                                                                                                                       Plastic Tape Plastic Core
There are two types of internal stresses for injection-molded products: one is the molding stress of the injection molded product, and the other is the temperature stress. As the melt enters the lower temperature mold, the melt near the walls of the mold cools and solidifies, and the molecular segments are "frozen". Due to the solidified polymer layer, the thermal conductivity is poor, resulting in a large temperature gradient in the thickness direction of the article. The solidification of the core of the product is so slow that when the gate is closed, the melting unit in the center of the product has not yet solidified, and the injection molding machine cannot feed the cooling shrinkage.

Thus, the internal shrinkage of the article is opposite to the direction of action of the hard skin; the core is in the static stretch and the surface is in static compression.

In the melt filling flow, in addition to the stress caused by the volume shrinkage effect. There is also the stress caused by the expansion effect of the runner and the outlet of the gate; the stress caused by the former effect is related to the direction of the melt flow, and the latter causes the stress in the direction perpendicular to the flow due to the effect of the outlet expansion.

Our company specializes in providing Plastic Tape Plastic Core. If you want to know more details, please pay attention to our website or feel free to contact us.