Common Problems and Countermeasures in TPE Injection Molding Process
Injection molding, also known as injection molding, is an injection molding method. The advantages of the injection molding method are fast production speed, high efficiency, automatic operation, a wide variety of patterns, shapes from simple to complex, and sizes from large to small. Moreover, the product size is accurate, the product is easy to be updated, and it can form parts with complex shapes. Injection molding is applicable to mass production, products with complex shapes and other molding processing fields. What problems are likely to occur during TPE injection molding? How to solve it? Now let's introduce.
1. Lack of glue in injection molding
The phenomenon that the end of the mold cavity is not filled is called glue shortage. This is mainly caused by improper molding conditions such as insufficient glue filling, but it can also be caused by insufficient exhaust or uneven rubber flow path (multi cavity mold) during molding.
2. Silver stripe appears
The phenomenon of radial stripes around the glue injection opening is caused by the vaporization of moisture or volatile components in the material. Among them, the air involved in the plasticizing process or left in the mold will also lead to this phenomenon. Therefore, it is necessary to fully dry the hygroscopic materials before molding and reduce the molding temperature of the materials that are easy to produce decomposition gases.
3. Blowhole generated by injection molding
Collapse holes in injection molded products are mainly caused by shrinkage of molded products during cooling in the mold. In addition to the requirement that the material must fill the mold cavity, rapid cooling is also very necessary. Specifically, it is to increase the holding pressure (secondary pressure) and reduce the processing temperature of thermoplastic elastomer materials and mold cooling temperature. In addition, the shape of injection molded products also has a great dependence. Because air holes are easy to appear in thick parts, such products should be provided with glue injection ports or glue flow channels around them.
4. Burr (flash) caused by injection molding
This is caused by the overflow of thermoplastic elastomer material from the mold cavity. For rubber injection molding, burr is normal, but it is abnormal for resin or thermoplastic elastomer. The reasons are: (1) Compared with rubber compound, molten resin or thermoplastic elastomer has higher fluidity and lower injection pressure; (2) Contact with the mold, cool, and instantly cure and stop the flow. Therefore, resin or thermoplastic elastomer is usually not prone to burrs. As a countermeasure, first of all, it is necessary to reduce the filling amount, reduce the pressure holding and shorten the pressure holding time. In addition, it is necessary to repair the dies with poor dimensional accuracy and gaps on the parting surface.
The above problems and solutions in TPE injection molding process are simply shared here. TPE products have excellent colorability, environmental protection and non-toxic. It can be molded by secondary injection molding, coated and bonded with PP, PE, PC, PS, ABS and other matrix materials, or molded separately.