5. Demoulding
The vulcanized liquid silicone rubber easily adheres to the surface of the metal, and the flexibility of the product makes it difficult to demold. The high temperature tear strength of LSR enables it to be demolded under normal conditions, and even larger products will not be damaged. The most common demolding techniques include stripping plate stripping, stripping pin stripping and pneumatic stripping. Other common techniques are roller scraping, ejector stripping, and automatic die casting.

When using the demolding system, it must be kept within the high precision range. If the gap between the top pin and the guide pin sleeve is too large, or if the gap becomes larger due to long-term wear and tear of the components, it may cause glue overflow.

Inverted cone or mushroom top push pins work well because they allow for higher contact pressure for improved sealing.

6. Mould material
Mold pallets are commonly made of non-alloy tool steel (No.1.1730, DIN code C45W). For mold pallets with a high temperature of -210 °C, considering the impact resistance, pre-tempered steel (No.1.2312, DIN code 40CrMn- MoS86) made. For the mold pallet with mold cavity, it should be made of mold steel that has been heat treated by nitriding or tempering to ensure its high temperature resistance.

For LSR with a high filling level, such as oil-resistant LSR, it is recommended to use a material with a higher hardness to make the mold, for example, bright chrome-plated steel or powder metal specially developed for this purpose (No. 1.2379, DIN code X155CrVMo121). When designing molds for high-wear materials, those parts that are subject to high friction should be designed to be replaceable so that the entire mold does not have to be replaced.

The inner surface of the cavity has a great influence on the finish of the product. Most obviously, the shaped article will conform exactly to the cavity surface. Molds for transparent products should be made of polished steel, surface-treated titanium/nickel steel is extremely wear-resistant, while polytetrafluoroethylene (PTFE)/nickel makes demolding easier.

7. Temperature control
Generally speaking, it is advisable to use electric heating for the molding of LSR, usually by heating with a belt heater, a cartridge heater or a heating plate. The key is to have an even distribution of the temperature field throughout the mold to promote uniform curing of the LSR. On large molds, the most cost-effective heating method is to push the oil temperature to control the heating.

Covering the mold with a thermal insulation board is beneficial to reduce heat loss. Improperity of any part of the hot mold may cause it to suffer large temperature fluctuations between operating procedures, or cause outgassing. If the surface temperature drops too low, the curing speed of the compound will slow down, which often makes the product unable to release the mold, causing quality problems. A certain distance should be maintained between the heater and the parting line to prevent the template from being warped and deformed, resulting in the formation of overflowing burrs on the finished product.

When designing a mold for a cold runner system, complete separation must be ensured between the hot and cold ends. Specialized titanium alloys such as 3.7165[TiA16V4] can be used because of their much lower thermal conductivity compared to other steels. For an integral mold heating system, the heat shield should be placed between the mold and the mold carrier to minimize heat loss.

Proper design and conception ensures LSR injection molding, where the mold is very important. The above mold design principles are aimed at filling the mold cavity with the rubber compound, shortening the curing time, high quality of the finished product, and high output, so that the silicone rubber processor can obtain good economic benefits.