What is the "shrinkage rate of TPE raw materials" to show you
Source：德创化工Time：2020-03-20Hits：3075
TPE material shrinks during molding. Generally speaking, customers should consider the shrinkage characteristics of TPE material when opening the mold. There is another case of shrinkage of injection molded products by customers. Previously, other raw materials were used, but now TPE materials are used instead, resulting in different shrinkage. Shrinkage is a common problem in TPE molding, because TPE products shrink after cooling.
The shrinkage of TPE is about 1.1~1.5%. Generally speaking, the larger the proportion of TPE, the smaller the shrinkage rate, the lower the hardness, and the shrinkage rate shows an increasing trend. In order to reduce shrinkage of products, the shrinkage rate of supplier materials can be consulted before mold opening and production.
Shrinkage can be improved by molding process. First, the pressure maintaining of injection molding is to push the melt near the gate into the mold cavity to slow down the shrinkage of the melt at the gate position. Proper pressure keeping setting can make the melt filled tightly, prevent glue shortage and reduce shrinkage. In fact, this is not difficult to understand.
After TPE materials are molded into products, due to insufficient cooling time, there will be obvious post-shrinkage, shrinkage during cooling and placing of products, which will further lead to shrinkage of products. By prolonging cooling time, shrinkage of TPE products can be improved.
The product structure will also affect the shrinkage. The larger the thickness is, the more serious the shrinkage of the product may be. The shrinkage position of TPE product is basically at the gate position. The reason is that the gate position has the largest shrinkage trend after the injection of glue. Slight shrinkage is shown as water lines. Severe shrinkage can make the surface near the gate uneven. If the wall thickness of the product structure is relatively thin, the shrinkage will also be reduced.
The molding shrinkage of TPE materials can be improved by the above methods, and then the molding temperature can be reduced. Under the premise of not affecting the performance and appearance of TPE products, low-temperature injection molding is adopted. The commonly used injection molding temperature of TPE materials is between 150 and 220, and the temperatures of encapsulated PA and ABS will be higher. It is recommended to be between 210 and 250. You can also consult the technical personnel of Dechuang Chemical.
