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Design Essentials of Liquid Silicon Molding Technology


1. Liquid silicone molding adopts liquid temperature control technology to control the barrel and nozzle temperature between 5-25. Usually, cooling water is used as the cooling medium.


2. Liquid silicone molding In order to prevent liquid silicone from solidifying, hydraulically driven needle valve type sealing nozzles are used. The needle valve immediately closes the nozzle after injection.
 
3. In the process of liquid silicone molding at Packson Mold, the mixing uniformity of the A and B rubber compounds directly affects the quality of the vulcanized products. In the case of high product quality requirements, the degree of mixing of the rubber materials after passing through the static mixer cannot be complete. Meet the requirements. At this time, the supplement of the screw can better meet the criteria. Because the rubber is liquid and does not need to undergo plasticization, the screw is designed to have no compression or low compression and a weak shearing effect. It does not require a large aspect ratio.
 
Generally, it is not suitable to directly use the screw structure on the injection molding machine because the screw structure usually has a strong shearing effect, which is easy to cause local vulcanization and affect the product's performance. Therefore, designing a screw specifically for the liquid silicone injection machine is vital. Suppose the product quality requirements are not high. In that case, you can consider using a plunger instead of a screw to complete the injection.
 
4. Liquid silicone has low molding viscosity. Lower injection pressure can produce higher injection speed, and air trapped in the mold can easily draw into the product. In order to make high-quality products, consider vacuuming the mold before injection. It is also possible to adjust the clamping force to achieve the purpose of driving away air. When the clamping pressure is low, the liquid silicone is filled to 90%-95% of the cavity. Then the clamping force increases, effectively exhausting gas and preventing the liquid silicone from overflowing and causing the flash.
 
5. It is easy to form backflow during liquid silicone injection, so the sealing effect of the non-return ring must be good. It is generally not suitable to directly apply the non-return structure on the injection molding machine. Its working process: when the screw is measured, the rubber material pushes the anti-reverse ring under the thrust of the screw. It enters the head of the screw through the hole on the rubber ring. 


6. The liquid silicone rubber manufacturing process requires cold runner technology, and the runner should be cold enough. There needs to be a good enough heat insulation effect between the runner and the mold to ensure that the liquid silicone will not vulcanize in the runner and block the nozzle, which will help reduce waste and save costs.

 
7. If the liquid silicone molding is extremely soft, sensitive, and demanding, consider adding a pneumatic brush to clean the mold and using a robot to eject the product.


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