Mold is becoming more and more popular in production with high volumes. It is certain that there are various methods during the molding process, such as the transfer molding and injection molding. The compression molding is a particular way as well. It is a forming process in which a plastic material is placed directly into a heated metal mold, then is softened by the heat, and forced to conform to the shape of the mold as the mold closes.
Its process starts with an allotted amount of plastic or gelatin inserted into a heated mold. Then a top force is needed to close the mold. Afterwards, enough pressure and heat are applied into forcing the inner materials into contact with all mold areas and should be maintained during the whole process until the molding material has cured. Then, it is time to wait till the material being cooled. The perfect shape for the product has completed indeed. It is to have seen that the process is a high-volume, high-pressure method suitable for molding complex, high-strength fiberglass reinforcements.
The common types for this method are listed in the following. They are the flash plunger-type, straight plunger-type, and the “landed” plunger-type molds. And it is certain that all the types hold a wide range of sizes. Generally speaking, it is commonly used for manufacturing electrical parts, dinnerware, and gears, buttons, buckles, knobs, handles, appliance housing, radio cases, and large containers and so on. As it has introduced, the idea of being popular of compression molding comes to minds, I suppose. So, what are the special characteristics and competitive advantages which lead to the popularity?
It is should be mentioned firstly that the advanced composite thermoplastics can be used as materials for molding which is different from the other molding process. And the materials in this process are usually preheated and measured before molding which is of great favors to reduce excess flash. And the ability to mold large, fairly intricate parts with low cost appears to be the most competitive advantage among various molding processes.
Apart from these, there are other points it needs to be improved. The poor product consistency and difficulty in controlling flashing and being not suitable for some types of parts are some of them. In order to make full use of the compression molding, there are six points that the engineer or the designer should keep in mind. They are to determine the proper amount of material, the minimum amount of energy required to heat the material, the minimum time required to heat the material and the appropriate heating technique should, to predict the required force to ensure that shot attains the proper shape, to design the mold for rapid cooling after the material has been compressed into the mold.