Design of Liquid Silicone Rubber (LSR) Injection Mold
2023-12-14
In mold design, there are generally the following forms:
1) Hot runner
It is relatively wasteful of materials, has simple design and low cost, and is mostly used for large products.
2) Cold runner with needle valve
It can be automated and the cycle is short.
3) Cold runner without needle valve
Due to the high coefficient of expansion of LSR, which expands when heated and contracts slightly when cooled, the part cannot maintain precise side margins in the mold. Therefore, cold runner processing can be used. LSR should maintain a lower temperature and fluidity. The cold runner adopts a closed system. In the injection cycle, the closed system uses a "sealing needle" or "needle valve" in each runner. " to control the accurate measurement of LSR materials.
Because silicone rubber has significant thermal expansion characteristics, the shrinkage rate is 2% to 4% (vulcanization temperature is 150°C), and silicone rubber has the characteristics of compression deformation.
