What should be paid attention to in injection molding of liquid silicone?

Liquid silicone is a kind of non-toxic, heat-resistant, high-resilience flexible thermosetting material. Compared with solid high-temperature vulcanized silicone rubber, it is a liquid glue, which has good fluidity, fast vulcanization, safer and more environmentally friendly, and can fully meet food requirements. In addition to these requirements, liquid silicone products have good softness, and the hardness can reach 10-40 shore A. Because of its soft characteristics, it is widely used in artificial human organs, medical silicone chest pads, and so on.

LSR is a two-liquid rapid vulcanization material with platinum as a catalyst. It can be produced by injection molding, mass, rapid vulcanization, and repetitive mechanical production. Its products have good thermal stability, cold resistance, and excellent electrical insulation properties. It does not produce toxic substances during combustion. However, due to the high expansion coefficient of LSR, it expands when heated, but shrinks slightly when cooled. Therefore, the parts cannot maintain accurate side margins in the mold due to silicone rubber. It has significant thermal expansion characteristics, the shrinkage rate is 2 to 4% (vulcanization temperature is 150 ℃), and silicone rubber has the characteristics of compression deformation.

In addition, the cured LSR is easy to stick to the metal surface. Commonly used demoulding techniques include ejector pin ejection and air ejection. Liquid silicone is divided into A glue and B glue, and the ratio of the two is 1:1 with a quantitative device. , After injecting the injection tube, the injection molding is carried out. The liquid silicone is injected into the hot runner mold to make silicone products, which can achieve the advantages of one-time molding, no waste, and automation.