In mold design, there are generally several forms:

1) Hot runner is a waste of materials, with simple design and low cost, and is mostly used for large products.
2) The cold flow channel with a needle valve can achieve automation and has a short cycle.
3) Due to the high coefficient of expansion of LSR, the cold runner without needle valve will expand during heating, but there will be slight shrinkage during cooling, so the components cannot maintain precise side distance in the mold. So cold channel processing can be used, and LSR should maintain low temperature and fluidity. The cold channel adopts a closed system. In the injection cycle, the closed system uses "sealing needles" or "needle valves" in each channel to control the accurate measurement of LSR material.

Due to the significant thermal expansion characteristics of silicone rubber, the shrinkage rate is 2-4% (vulcanization temperature is 150 ℃), and silicone rubber has the characteristic of compression deformation.

1) To avoid turbulence and jetting, use a small injection nozzle.
2) Using needle or wing shaped injection ports
3) Replace cylindrical guide bolts with T-shaped guide bolts, use air blowing method during demolding, and add insulation layer/plate.
4) Do not use rust inhibitors/oils containing polymerization inhibitors, usually toluene, xylene, etc.

In addition, cured LSR is prone to sticking to metal surfaces, and the most commonly used demolding techniques include pin ejection and air pushing.

Methyl silicone Gum IOTA 101