The molding process is the production process of solid silicone rubber. The upper and lower modules are combined and a mold core is placed in the middle, so it is called molded silicone rubber. The main production process of molded silicone rubber products is the silicone processing process in which silicone rubber raw materials are formed into products by heating and pressurizing in the closed mold cavity. Usually, the raw materials are evenly stirred into rubber mixture through the mixer, and the mold is moved into the vulcanization molding machine. Then the mold is closed and pressurized to form, cure or vulcanize, and then demoulded to obtain silicone rubber products. This process is suitable for the processing of thermosetting materials.

Advantages of molded silicone rubber products

1. It can be made into any shape

2. High precision, regular and beautiful commodity shape

3. The color is bright and can be colored at will

Disadvantages of molded silicone rubber products

1. Limited product size

2. Many burrs and wastes will occur in the production process

3. The mold cost is relatively high and the development cycle is long

Problems needing attention in molding

1. When silicone products are formed, silicone rubber is pressed under high pressure, which cannot be eliminated due to the cohesion of elastomer. When silicone rubber is formed and removed from the mold, it often produces extremely unstable shrinkage (the shrinkage rate of silicone varies due to different rubber types). It can be relaxed and stable only after a period of time. Therefore, at the beginning of silicone rubber product design, careful calculation and comprehensive consideration should be taken regardless of formula or mold, otherwise it is easy to cause instability of silicone rubber product size and decline of product quality.

2. Silicone rubber is a thermosetting elastomer, while plastics are thermosetting. Due to different types of silicone curing agents, there is a considerable gap in the temperature range of molding and curing of silicone rubber. Even silicone rubber curing can be affected by climate change and indoor temperature and humidity. Therefore, the production conditions of silicone rubber products need to be adjusted appropriately at any time, otherwise, there may be differences in product quality.

3. Silicone rubber products are made from silicone rubber raw materials after internal mixer mixing. The formula is designed according to the characteristics of the required silicone rubber products, and the required product hardness and the type of silicone rubber vulcanizing agent are determined. Silicone rubber products are molded by rubber flat vulcanizer. After the product is formed, the flash treatment shall be carried out at last, and the product surface shall be smooth without burr.

4. Problems such as die sticking, edge warping, bubbles and incomplete vulcanization white spots will occur in the process of silicone rubber molding and vulcanization. It is necessary to adjust the die temperature, exhaust time and die pressure.