Does the shrinkage rate of liquid silicone encapsulated products affect the accuracy of the product?
Liquid silicone, as a high-performance elastic material, has been widely used in various fields such as medical, consumer electronics, automotive electronics, and baby products due to its excellent high-temperature resistance, aging resistance, chemical corrosion resistance, and good biocompatibility. And the encapsulation process is to cover or wrap the surface of other materials such as plastic, metal, etc. with liquid silicone in a specific way, forming a layer of silicone protective layer or bonding layer to enhance the appearance, texture, functional performance, and service life of the product.
Shrinkage characteristics of liquid silicone gel:
During the curing process of liquid silicone gel, there will be a certain degree of volume shrinkage due to the rearrangement of molecular chains and cross-linking reactions. This shrinkage is an inevitable phenomenon in the solidification and molding of materials, but its degree is influenced by various factors, including but not limited to the formula of silicone, curing conditions (such as temperature and time), mold design, and the properties of the coating substrate. The control of shrinkage rate is crucial for ensuring product quality, especially in application scenarios that have strict requirements for product accuracy.
The impact of shrinkage rate on product accuracy:
1. Dimensional stability
The dimensional stability of liquid silicone encapsulated products is directly affected by the shrinkage rate. If the shrinkage rate is not properly controlled, it may cause the product size to deviate from the design standards, thereby affecting the assembly accuracy and performance of the product. For example, in the sealing or connecting components of electronic products, even small dimensional deviations can cause problems such as poor sealing or connection failure.
2. Surface flatness
Surface flatness is one of the important indicators for measuring the appearance quality of products. During the encapsulation process, if liquid silicone shrinks unevenly, it will form uneven surfaces on the product, which not only affects its appearance but may also reduce its sealing and wear resistance. Especially in medical devices or high-end consumer goods that require extremely high surface quality, this issue is particularly prominent.
3. Functional performance
For certain functional products, such as sensors, buttons, etc., the coating layer of liquid silicone not only needs to provide a good touch and appearance, but also needs to ensure the normal functioning. The change in shrinkage rate may affect key performance indicators such as bonding strength, conductivity, and insulation between the silicone layer and the substrate, thereby affecting the overall functional performance of the product.
silicone injection molding
Strategies for controlling shrinkage rate:
Given the significant impact of shrinkage rate on the accuracy of liquid silicone encapsulation products, manufacturers need to take a series of measures to effectively control its shrinkage rate and ensure the stability and consistency of product quality.
1. Optimize the silicone formula:
By adjusting the formula of silicone, such as changing the type and amount of crosslinking agent, adding appropriate fillers or plasticizers, the curing speed and shrinkage rate of silicone can be adjusted to a certain extent. Reasonable formula design is the foundation for controlling shrinkage rate.
2. Precise control of curing conditions
The curing temperature and time are key factors affecting the shrinkage rate of silicone gel. By precisely controlling the temperature curve and time schedule during the curing process, the shrinkage rate can be effectively reduced and its uniformity can be improved. In addition, advanced processes such as preheating molds and segmented curing can further optimize the curing effect.
3. Optimize mold design:
Mold design directly affects the flowability and shrinkage behavior of liquid silicone gel during the curing process. By optimizing the structural design of the mold, increasing the demolding slope, and adopting split type molds, the internal stress and shrinkage deformation of silicone during the curing process can be reduced, and the dimensional accuracy and surface quality of the product can be improved.
Skills of operators:
The skills and experience of operators in gluing, curing, and post-processing operations can also affect the final accuracy of the product.
To reduce the accuracy issue of liquid silicone encapsulation products, the following measures can be taken:
Accurately predict and compensate for shrinkage during the design phase.
Choose high-quality liquid silicone materials and molds.
Control and optimize curing conditions.
Conduct strict quality control and inspection to ensure that the product meets the accuracy requirements.
