How to secondary mold solid silicone onto plastic parts?
The secondary molding of solid silicone onto plastic parts usually involves a series of complex process steps and technical points. Here is a detailed explanation:
1、 Material preparation
Solid silicone: Choose solid silicone that meets environmental requirements and has excellent processing performance as the base material.
Plastic parts: Ensure that the material of the plastic parts is compatible with solid silicone to achieve good adhesion. At the same time, plastic parts should undergo appropriate pre-treatment, such as cleaning, degreasing, etc., to improve the bonding effect.
2、 Mold design and manufacturing
Mold design: Based on the product design drawings, accurately design the encapsulation mold. The design of the mold needs to consider factors such as material fluidity, shrinkage rate, and demolding angle to ensure the shape, dimensional accuracy, and surface quality of the coating layer.
Mold manufacturing: Using high-precision processing technology to manufacture molds, ensuring that the accuracy and surface quality of the molds meet production requirements.
3、 Secondary molding process
Coating and positioning:
Apply solid silicone evenly onto the surface of pre treated plastic parts through manual brushing, impregnation, spraying, or injection molding.
During the coating process, it is necessary to strictly control the coating thickness to avoid uneven curing caused by local thickness or thinness.
At the same time, ensure precise positioning of solid silicone and plastic parts to avoid misalignment.
solidification:
Place the coated product at the set temperature for curing. The curing time and temperature need to be adjusted according to the material characteristics and mold design.
During the curing process, it is necessary to maintain a uniform temperature to avoid the generation of internal stress.
Post processing:
After solidification is completed, necessary post-treatment processes such as cooling, demolding, and trimming are carried out to ensure that the product meets the design requirements.
Conduct quality inspections on products, including testing of appearance, size, performance, and other aspects.
Material preparation, mold design and manufacturing are require
4、 Key points of bonding technology
Cleaning and surface treatment: Before bonding, ensure that the bonding surface of solid silicone and plastic parts is clean, dry, and free of impurities such as grease and dust. For certain special materials, special treatment agents may be required to enhance the bonding effect.
Choose the appropriate adhesive material: Select the appropriate adhesive material based on the specific characteristics of solid silicone and plastic parts. For example, strong adhesive silicone glue or universal glue can be chosen.
Temperature and time control: Appropriate temperature and time are key factors in ensuring successful bonding. It is necessary to control the appropriate temperature and time according to the specific material characteristics to ensure that the adhesive can fully cure and produce stable bonding force.
5、 Application Cases
In electronic products, such as the strap and button area of smart watches, the secondary molding technology of solid silicone and plastic parts is often used. Through this technology, a layer of wear-resistant plastic material (such as TPU) can be coated on the surface of silicone watch straps to enhance their tear resistance and aesthetics. At the same time, the secondary molding technology of silicone and hard plastic is used in the button area, which not only ensures the soft touch of the button, but also improves the feedback strength and durability of the button.
In summary, the secondary molding of solid silicone onto plastic parts involves multiple steps and technical points. Through precise mold design, reasonable selection of process parameters, and strict quality control, it is possible to achieve strong adhesion and excellent performance between solid silicone and plastic parts.
