What are the precautions for TPE encapsulation molding?

TPE encapsulation molding, also known as two-color/multi-color injection molding, is an advanced manufacturing process that involves coating TPE material onto another substrate. This process can create products that combine soft touch, good elasticity, anti slip performance, and beautiful appearance, such as sports equipment handles, tool grips, phone cases, electronic product cases, etc. However, the success of TPE encapsulation molding is not an easy task, as it has extremely high requirements for process parameters, material selection, and mold design. So what are the precautions for TPE encapsulation molding? Let's take a look together with Shenzhen Zhongsu Wang TPE editor below!

The precautions for TPE encapsulation molding are as follows:

1、 Material matching

Successful encapsulation begins with the appropriate combination of materials. Not all TPEs can naturally and firmly bond with substrates. The type of TPE (such as TPE-S, TPE-E), hardness, flowability, and surface characteristics of the substrate collectively determine the adhesive strength. Therefore, strict compatibility testing must be conducted to select TPE formulations that meet both product performance requirements and have good adhesion to the substrate. Ignoring this point, even if the process is perfect, it may still lead to product failure due to interface delamination.

2、 Mold design

Typing surface and bonding line: Careful design is required to ensure that TPE can fully flow and cover the substrate, forming an ideal bonding area while avoiding obvious weld marks.

Exhaust system: It must be well designed to ensure that the air inside the mold cavity can be smoothly discharged during TPE injection, preventing trapped air from causing product shortage or poor bonding.

Cooling system: Uniform and efficient cooling can control the curing speed of TPE, affecting product size stability and demolding difficulty.

3、 Process parameters

TPE temperature: If the temperature is too high, TPE is prone to decomposition, and although it has good fluidity, it may lead to unstable dimensions; The temperature is too low, the fluidity is poor, it is difficult to fill the cavity, and even unable to effectively wrap the substrate. The optimal balance point needs to be found through experiments based on the characteristics of TPE and product structure.

Injection pressure and speed: It is necessary to ensure that TPE can fill the mold cavity with sufficient pressure and appropriate speed, avoiding substrate deformation or TPE flash caused by excessive pressure, as well as preventing incomplete filling or weak bonding caused by insufficient pressure or slow speed.

Pressure holding and cooling time: The pressure holding time should be sufficient to establish a stable bond between TPE and the substrate, while the cooling time should ensure that the product is completely cured and shaped to avoid demolding deformation.

4、 Substrate processing

Cleanliness: The surface of the substrate must be thoroughly cleaned and free of pollutants such as oil, dust, and moisture, which are the enemies of adhesion.

Surface activation: Sometimes, the surface of the substrate is too smooth and requires slight sandblasting to increase roughness, or the use of specialized primers to chemically enhance interfacial bonding, or even advanced methods such as plasma treatment to achieve stronger mechanical bite and chemical bonding.

5、 Production stability

In addition to the above points, stability during the production process is also crucial. Batch differences in TPE materials, changes in environmental humidity, and fluctuations in injection molding machine performance may all affect the final product. Establishing strict quality control processes and regularly inspecting equipment and materials are crucial for ensuring long-term stable production and continuous production of qualified products.

In short, TPE encapsulation molding is a process that requires extremely high levels of detail. From material selection and mold design to process control and substrate treatment, every step requires careful design and strict control. Only by synergistically optimizing these elements can we overcome challenges and produce TPE coated products that are firmly bonded, have excellent performance, and have a beautiful appearance.