5 release

Through the vulcanized liquid silicone rubber is easy to adhere to the surface of the metal, the flexibility of the product will make it difficult to release. The high temperature tear strength of LSR allows it to be released under normal conditions, even larger products will not be damaged. The most common demoulding techniques include demoulding with formwork, demoulding with pin and pneumatic demoulding. Other common techniques include roller scraping, ejector plate demoulding and automatic molding. When using the demolding system, it must be kept in the high precision range. If the gap between the top promotion and the guide pin sleeve is too large, or the gap between the parts becomes large because of long time wear, it may cause glue overflow. The inverted cone or mushroom top is especially effective because it allows for greater contact pressure and improves tightness.

6 Mould Materials

Die support plates are usually made of non-alloy tool steel (No.1.1730,DIN code C45W). For die support plates that need to withstand high temperature of 170℃-210℃, in consideration of impact resistance, they should be made of pre-tempered steel (No.1.2312,DINcode 40 CrMN-M oS 8 6). The die supporting plate for the die cavity shall be made of nitriding or tempered b-tool steel to ensure its high temperature resistance. For high-volume LSRS, such as oil-resistant LSRS, it is recommended that the die be made of a harder material, such as bright chrome-plated steel or powder metal specially developed for this purpose (No.1.2379,DINcode X 155 CrVMo121). When designing molds for high-wear materials, those parts that endure high friction should be designed to be replaceable, so that the entire mold does not have to be replaced. The inner surface of the mold cavity has a great influence on the finish of the product. The most obvious is that the shaped product will be exactly the same as the cavity surface. Moulds for transparent products shall be made of polished steel. The surface treated chin/nickel steel is extremely resistant to wear, while PTFE/nickel makes demounding easier.

7 Temperature Control

In general, the molding of LSR should be electrically heated, usually with a belt heater, a cylinder heater or a heating plate. It is critical that the temperature field be evenly distributed throughout the die to promote uniform LSR curing. On large moulds, it is an economical and effective heating method when the push oil temperature control heating. Heat loss can be reduced by cladding the die with an insulated plate. The incompatibility of any part of the hot mold may cause it to suffer from large temperature fluctuations between operations, or cause air loss. If the surface temperature drops too low, the glue curing rate will slow down, which will often make the product can not be released, causing quality problems. A certain distance should be maintained between the heater and the parting line to prevent the formwork from warping and deformation and the formation of rubber overflow burr on the finished product. When designing a die for a cold runner system, ensure that the hot end and the cold end are completely separated. Special chin alloys such as 3.7165[TiA16V4] can be used because of their much lower thermal conductivity than other steels. For an integral die heating system, the heat shield shall be placed between the die and the die bracket to minimize heat loss. Proper design and design ensures LSR injection molding, where the die is important. The above design principles of the mold are designed to make the rubber fill the mold cavity, shorten the curing time, the finished product is of high quality and the output is high, so that the silicon rubber processor can obtain good economic benefits.