As a kind of environmental-friendly raw material, silicone is loved by people because of its superior performance. Its softness and non-toxicity are widely used in industrial seals and medical devices. In particular, its operating temperature : -60 to 250℃ is unmatched by plastic. Using silica gel to cover metal parts or plastic parts to form some new properties makes the product hard moderate, for example, silicone coated steel kitchen shovel, its environmental protection is popular with consumers. Silica gel is different from plastic. Silica gel is a kind of hot formed material, under the action of certain temperature, Silica gel raw material solidify to form the product that we want.
Silicone products usual molding processes are as follows :
- Extrusion molding process
Just as we squeeze the toothpaste, the extruder head is the section shape of the product, it has a certain length, under the action of force and temperature, the product from the extruder head has been vulcanized. The products formed by this process are generally strip products, and the cross sections of products can be various. For example, rectangular strip, ring silicon tube, etc.
- Epoxy process
The silica gel material is liquid, and the raw material is contained in the needle tube. The raw material is dripped onto the mould by pneumatic and manual operation, and the material is heated and vulcanized. This craft is a handicraft craft, and a lot of labor is needed. So the capacity is not high. It has a feature that a product can be dripped in a variety of colors as required. So this kind of craft is mostly for making handicrafts. For example, polychromatic silicone bracelet, various color patterns of silicone phone case, and so on.
- Solid-state hot press molding process
This process is to use the temperature and pressure of the hydraulic press, with the help of molds to vulcanize the product out. This process is relatively low in cost, high in output and widely applied. It is mostly used in monochrome silica gel products. It can also be applied to two-color and double hardness or multi-color and multi-hardness products, but the structure of the product is not flexible and limited.
It can also be applied to the package of plastic and package of metal, which is also not flexible in structure, and has temperature requirements for the package, which is generally required to withstand 180℃ and do not deform.
- Liquid injection molding process
This process requires equipment such as silica gel ejector, pressure feeder. Its raw material is water thick shape, divided into two groups of A and B. The principle of it is that the raw materials of group A and B are pressed into the barrel of the ejector at 1 : 1 by using the compactor, and then mix them, press it into the hot mold cavity to form. The molding temperature of this process is relatively low, 130℃ is enough. It can be used in less heat-resistant plastic encapsulation molding, which has an advantage over solid-state hot press molding. It has a high output and is easy to automated production. But the cost of raw materials is several times higher than that of solid silica gel.
In a word, no matter which process, that can achieve performance requirements and achieve low prices is the best process.