The eva foam sole is mainly a process of small foaming in the mold
EVA foam generally has three processes, small foaming in the mold, injection process and traditional flat plate large foaming
1. Small foaming in the mold. This process is mainly used in shoe materials. Sports shoes do the first foaming of the midsole twice. According to the formula, the material is granulated, weighed and put into the opened mold , the foaming is the general shape of the shoes. The difficulty of this process is the symmetry of the mold and the formula, otherwise it is difficult to control the magnification and hardness at the same time. Often the size is qualified and the hardness is not enough, and the hardness is too small. The development of this process The bubble conditions are relatively flexible, depending on the shape and structure of the product, of course, it is mainly the change of time, and the change of temperature is not large.
I mentioned the 2nd midsole earlier, here is the 2nd molding. Grind off the skin of the previously foamed rough embryo, press it into the finished mold, and heat and cool the two steps to form the product. The heating temperature is 125-135 It is more suitable, the pressure is 50KG\/square CM, after heating for a certain period of time, it is water-cooled, and it is taken out to be a 2-time midsole. The size of this compressed bottom is relatively stable, and the physical properties are relatively better.
2. Injection process. This process will be the mainstream in the future. A product can be produced after one process, but the precision of the mold is higher. The principle is similar to the injection molding in the plastic industry, but the injection molding is to open the mold immediately, and the temperature of the mold is different. That is, the injection of EVA is to adjust the mold temperature and opening time of plastic injection molding.
3. Large foaming of the traditional flat plate. This process produces a plate, and then it is made into a product through punching, edging and other processes. The foaming condition is relatively fixed, the temperature is 160-170, and the time is determined by the thickness of the mold, generally 90 -110 seconds\/MM, pressure 150KG\/square CM.
