Injection point
Cold runner system is used for LSR molding. The utility model can maximize the advantages of the rubber compound and increase the production efficiency to the maximum. In such a way to process products, it is not necessary to remove the glue injection channel, so as to avoid increasing the labor intensity of operation, and sometimes avoid a large amount of waste of materials. In many cases, the operation time can also be shortened without glue injection channel structure.
The injection nozzle of rubber material is controlled by needle valve for forward flow. At present, many manufacturers can provide the injection nozzle with air control switch as standard equipment, and can set it in various parts of the mold. Some mold manufacturers have developed an open cold runner system with a very small volume, so that multiple injection points (and thus the entire mold cavity) are set in a very limited mold space. This technology makes it possible to produce high quality silicone rubber products in large quantities without separating the injection port.
If a cold runner system is used, it is important to form an effective temperature gap between the hot cavity and the cold runner. If the runner is too hot, the compound may start vulcanizing before injection. But if it cools too fast, it will absorb too much heat from the gate area of the mold, resulting in incomplete vulcanization.
For products injected with conventional sprues (such as submerged sprues and conical sprues), it is suitable to use small-diameter injection port (the diameter of the feeding port is usually 0.2mm-0.5mm) for pouring. LSR compound with low viscosity is just like thermoplastic compound, so it is very important to balance the flow channel system. Only in this way, all cavities will be filled evenly with compound. Using the simulation software to design the runner system can greatly simplify the development process of the mold, and its effectiveness is proved by the mold filling test.