Precautions for TPE Overmolding
TPE over-molding is a process that involves encapsulating a rigid plastic part with a soft TPE material. It is widely used in electronics, automotive parts, and sporting goods.
1. Material Preparation
Material Drying: TPE materials are often sensitive to moisture. Some TPE materials require drying before processing to remove moisture.
Material Compatibility: Ensure good compatibility between the TPE material and the substrate (such as plastic or metal).
2. Injection Molding Machine
Machine Selection: Choose an injection molding machine suitable for the size, shape, and production volume of the product. For TPE over-molding, the injection volume, injection pressure, and clamping force of the machine must meet the process requirements.
Screw Design: The screw design of the injection molding machine is also important for TPE overmolding.
3. Mold Design
Gating System: The mold's gating system should be designed to ensure that the TPE material fills the cavity evenly. A hot runner system is a good choice for TPE overmolding as it can maintain the fluidity of the TPE material and reduce pressure loss and temperature drop in the runner.
Venting Design: Since TPE materials generate some gas during injection, the mold should have a good venting design. Venting grooves or holes can be set in the mold parting line, deep cavity, and other locations to vent the gas.
Gate Location: The location and type of the gate significantly affect the TPE overmolding effect.
4. Injection Molding Process
Temperature Control: The processing temperature of TPE materials is generally between 160°C and 220°C, but the specific temperature should be determined according to the specific formula and product requirements of the TPE.
Injection Speed: The injection speed also has a significant impact on the quality of TPE over-molding.
Holding Pressure and Cooling: The holding pressure stage is important for the dimensional accuracy and bonding effect of TPE over-molded products. The holding pressure and time should be determined according to the product requirements and the characteristics of the TPE material.
