What details should be paid attention to when wrapping silicone with plastic?

When discussing the process of silicone encapsulation, we have to delve into its details because every tiny step may directly affect the quality and performance of the final product. Silicone wrapped plastic, as a common composite material molding technology, is widely used in various fields such as electronics, medical, automotive, toys, etc. The key is how to ensure the perfect combination between silicone and plastic while maintaining their respective excellent characteristics.

1、 Material selection

1. Considerations for Silicone Materials
Temperature resistance: Select appropriate temperature resistant silicone gel according to the product’s usage environment to ensure stable physical and chemical properties under high or low temperature conditions.
Hardness and elasticity: The hardness of silicone directly affects the feel and durability of the product, and needs to be adjusted according to actual needs. Meanwhile, good elasticity helps to resist impact and vibration.
Environmental friendliness: With the increasing awareness of environmental protection, it has become particularly important to use non-toxic, odorless, and ROHS compliant silicone materials.
2. Matching of plastic materials
Compatibility: Ensure that silicone is chemically compatible with the selected plastic material, avoiding mutual corrosion or affecting adhesive strength.
Shrinkage rate: The shrinkage rate of plastic materials should match that of silicone to reduce dimensional deviations after molding.
Processability: The flowability and injection temperature of plastic materials must meet the production process requirements to ensure a smooth injection molding process.

2、 Mold design

Accuracy and Durability: Mold design needs to consider the molding characteristics of silicone and plastic to ensure accuracy and durability, in order to produce products that meet the requirements.
Exhaust design: Silicone releases gas during the curing process, and the mold needs to be designed with reasonable exhaust holes to prevent the generation of bubbles and affect product quality.
Demoulding design: Reasonable demoulding slope and demoulding mechanism design can help reduce damage to the product during demoulding and improve production efficiency.

3、 Process control

1. Silicone injection process
Injection pressure and speed: Adjust the injection pressure and speed according to the fluidity of the silicone gel to avoid insufficient injection or overflow.
Curing temperature and time: Accurately control the curing temperature and time to ensure complete curing of the silicone, while avoiding performance degradation caused by over curing.
2. Plastic injection molding process
Injection molding temperature and pressure: Based on the characteristics of the plastic material, set the appropriate injection molding temperature and pressure to ensure uniform melting and smooth flow of the plastic.
Injection timing: After the silicone has reached a certain degree of solidification, plastic injection molding should be carried out immediately to ensure a tight bond between the two.

4、 Quality control

Online detection: By using visual inspection, size measurement and other methods, real-time monitoring of semi-finished products in the production process is carried out to detect and solve problems in a timely manner.
Finished product inspection: Conduct a comprehensive inspection of the finished product, including appearance, size, performance, etc., to ensure that the product meets quality standards.
Data recording and analysis: Establish a comprehensive production recording system to record and analyze various data during the production process, providing a basis for continuous improvement.

5、 Subsequent processing

Deburring and trimming: deburring and trimming the formed product to improve its appearance quality.
Cleaning and disinfection: Necessary cleaning and disinfection treatment should be carried out according to the product’s purpose to ensure product hygiene and safety.
Performance testing: Conduct necessary performance tests on the product, such as temperature resistance, corrosion resistance, impact resistance, etc., to ensure that the product performance meets the design requirements.

epilogue

The silicone wrap plastic process may seem simple, but it actually contains many details and techniques. From material selection to mold design, from process control to quality control, every link needs to be treated rigorously in order to produce high-quality products.