Information dynamics

Current position: Index >> News >> Technical Knowledge

What glue is better for liquid silicone rubber injection molding

2021-06-29

What is injection molding? It is a typical common process for producing silica gel and plastic products. Common silicone injection molding, rubber injection molding and plastic injection molding. So what glue is better for liquid silicone rubber injection molding? There are many liquid silicone molding processes: coating, potting, coating, injection, injection molding, (ultraviolet) UV curing, and room temperature vulcanization; today, Kang Libang takes everyone to inventory the liquid silicone rubber molding process. Focus on: Liquid silicone rubber injection molding (injection) production and processing methods and liquid silicone glue. It is a typical common process for producing silica gel and plastic products. Common silicone injection molding, rubber injection molding and plastic injection molding. Among them, match molds in different injection molding machines. Produce injection molded parts with certain functionality. Subdivided into compression molding injection molding and die-casting injection molding. Liquid silicone rubber injection molding is also called injection molding, which is a molding method of injection and molding. The advantages of injection molding method are fast production speed, high efficiency, operation can be automated, variety of designs and colors, shapes can be from simple to complex, sizes can be from large to small, and the product size is accurate, the product is easy to update, and it can be made into complex shapes. Parts and injection molding are suitable for mass production and molding processing fields such as products with complex shapes.


The liquid silicone rubber injection (injection) molding process can be roughly divided into the following six stages: mold clamping, injection molding, pressure holding, cooling, mold opening, and product removal. In this process, the quality of liquid silicone injection molding is generally closely related to temperature, pressure, and time: Among them, temperature control can be improved from three stages: barrel temperature, touch nozzle temperature, and mold temperature. The temperature of the nozzle is usually slightly lower than the maximum temperature of the barrel. The principle is to avoid the clogging of liquid silicone in the nozzle by vulcanization. The mold temperature is divided into three parts: heating, heat preservation and cooling. The mold temperature is determined by the vulcanization conditions of the liquid silicone rubber, the size and structure of the injection molded parts, performance requirements, and other process conditions (liquid silicone rubber thermal vulcanization temperature, injection speed and injection pressure, the time required for a single injection molded part, etc.). Liquid silicone rubber injection molding pressure control. Pressure control in injection molding is divided into plasticizing pressure and injection pressure, which directly affect the quality of injection molded parts.


①Plasticizing pressure: When the silicone rubber injection molding machine (back pressure) adopts a screw type injection machine, the pressure on the top of the screw when the screw rotates and retreats is called the plasticizing pressure, also known as the back pressure. The size of this pressure can be adjusted by the overflow valve in the hydraulic system. Increasing the plasticizing pressure will increase the shearing effect in proportion to increase the temperature of the hot vulcanized silicone rubber material; vice versa;


②Injection pressure (injection pressure)


The injection pressure of the liquid silicone rubber injection machine is calculated based on the pressure exerted on the liquid silicone rubber by the plunger or the top of the screw. The role of injection pressure in injection molding is to overcome the flow resistance of the silicone rubber material from the barrel to the cavity, give the silicone rubber a filling rate and compact the silicone rubber.




There are three measurement standards for good liquid silicone injection molded parts:


First, the appearance quality of liquid silicone injection molded parts, including completeness, color, and gloss;


Second, the accuracy between size and relative position, that is, size accuracy and position accuracy;


Third, the mechanical properties, chemical properties, electrical properties, etc. corresponding to the purpose, that is, functional


Defect analysis and solutions of liquid silicone injection molded parts


Appearance defects: silver streak discoloration, weld marks


Process problems: flash, shrinkage, lack of glue


Performance issues: warpage, embrittlement


The new technology of liquid silicone rubber injection molding is not limited to: micro-injection, high-fill compound injection, water-assisted injection, mixed use of various special injection molding processes, foam injection, mold technology, simulation technology, etc. Rubber machinery automation.