What is the difference between liquid silicone secondary molding and liquid silicone encapsulation?

When delving into the molding technology of liquid silicone rubber (LSR), we have to mention two common processes: secondary molding of liquid silicone rubber and encapsulation of liquid silicone rubber. Although both technologies are based on the excellent properties of liquid silicone, such as high elasticity, aging resistance, high and low temperature resistance, and good biocompatibility, there are significant differences in application scenarios, process and final product characteristics.

1、 Comparison of Process Principles and Processes

Secondary molding of liquid silicone gel:

Liquid silicone secondary molding, as the name suggests, refers to the second or multiple liquid silicone injection molding processes based on one or more preliminary molding. This process usually involves two or more independent molds. First, the initial molding of some components is completed in one mold. Then, these components are transferred to another mold and injected with new liquid silicone material to achieve secondary bonding. This technology is particularly suitable for components that require multi-layer structures or complex assembly relationships, such as the combination of anti drop borders and soft rubber back shells in mobile phone protective cases.

technological process:

Preliminary molding: In the first mold, liquid silicone is used to inject the basic part of the component, such as the hard frame.
2. Component preparation: The preliminarily formed components undergo cooling, demolding, cleaning, and other treatments to ensure a clean and flawless surface.
3. Secondary injection molding: Place the processed components in a second mold, inject liquid silicone, and tightly bond the two through high pressure and high temperature.
4. Post processing: including cooling, demolding, trimming, inspection, etc., to ultimately obtain the finished product.Liquid silicone encapsulation:
Liquid silicone encapsulation technology is a process of injecting liquid silicone onto the surface of a hard substrate (such as metal, plastic, etc.) to form a soft, wear-resistant, and anti slip protective layer. This technology is widely used in situations where it is necessary to improve product feel, wear resistance, or achieve specific functions such as anti slip and shock absorption, such as electronic product casings, tool handles, medical devices, etc.

technological process:

1. Substrate preparation: Place the hard substrate to be coated precisely in the mold to ensure accurate positioning.
2. Liquid silicone injection: After the mold is closed, liquid silicone is injected into the mold through a precision injection molding machine to cover and tightly adhere to the surface of the substrate.
3. Solidification molding: Under high temperature and high pressure, liquid silicone gel quickly solidifies and forms a strong bond with the substrate.
4. Post processing: including demolding, trimming, inspection, etc., to ensure that the product has a perfect appearance and meets functional standards.

2、 Performance characteristics and application differences

Performance characteristics:

Secondary molding of liquid silicone: Through secondary molding, products can have more complex structures and higher design freedom, while maintaining the excellent performance of liquid silicone. Materials of different levels can be selected according to needs to achieve complementary functions.
Liquid silicone encapsulation: The surface of the product after encapsulation has an excellent tactile sensation, while improving the durability and aesthetics of the product. Due to the tight bonding between liquid silicone and the substrate, it can effectively prevent the substrate from being corroded or worn.

Application differences:

Liquid silicone secondary molding is more suitable for scenarios that require multi-layer structures with significant differences in material properties between layers, such as the design of protective covers for consumer electronics products, which can provide both hard protection and maintain a soft touch.
Liquid silicone encapsulation is widely used to improve the surface texture, wear resistance, and slip resistance of products, especially in fields that require high safety and comfort, such as medical equipment and sports equipment.

3、 Technical Challenges and Solutions

Both liquid silicone secondary molding and encapsulation technology face certain technical challenges, such as material flowability control, ensuring the strength of the bonding interface, mold design and manufacturing accuracy, etc. In response to these challenges, manufacturers need to continuously optimize process parameters, improve equipment accuracy, enhance mold design and manufacturing capabilities, and strengthen material research and development to meet increasingly diverse market demands.
In summary, liquid silicone secondary molding and liquid silicone encapsulation, as two important molding technologies, play an irreplaceable role in their respective application fields. Understanding their differences and characteristics helps us better select and apply these technologies, promoting innovation and development in product design.