What is the shrinkage rate of TPE sealant? Dechuang answers for you
Source：德创化工Time：2021-06-01Hits：1829
Shrinkage of TPE encapsulation is one of the properties that should be paid attention to in industry research and development and production. When TPE encapsulation material starts to cool from molten state, its molecules will align with each other, and shrinkage will change here.
The shrinkage size of TPE material is about ten thousandths of the product shape, but it can seriously affect the shape of TPE products and the difficulty of demoulding. If the shrinkage is uneven, the phenomenon of bending or warping will also occur. Even if it is within the acceptable shrinkage range, it will have a certain impact on the connection of parts.
For these reasons, shrinkage must usually be taken into account in the production process:
1, demoulding the workpiece; When the workpiece contains cores or hollowed-out parts, with the shrinkage of the elastomer, it will tightly wrap these parts of the mold, which makes it difficult to demould the workpiece. Mold design, mold surface finish and processing conditions can reduce this influence, and even make automatic demoulding possible.
2. Molding conditions; Molding conditions can significantly affect the degree and nature of shrinkage. If it changes from high stress state to low stress state quickly, the degree of shrinkage will increase. Rapid cooling of the workpiece and high injection speed or pressure can also affect the shrinkage.
3. Design considerations; Considering the shrinkage, the die must be machined to be slightly larger than the required size of the workpiece. Usually, the actual shrinkage value can only be known when the specific workpiece is formed. Therefore, it is always best to be conservative in advance.
As with various other properties of thermoplastic elastomers, shrinkage tends to vary with the direction of polymer flow. The location of the gate will determine the direction of melt flowing into the mold, and thus the shrinkage. Dongguan Dechuang Chemical Co., Ltd. is a professional R&D, production and sales of thermoplastic elastomer TPE/TPR rubber and plastic raw materials. Dechuang Chemical can customize TPE raw materials with different needs according to customer requirements. For more information about TPE raw materials, please feel free to contact us and we will serve you wholeheartedly!
