1. Second injection or double color injection
It is implemented on a two-color injection machine. A TPE material is injected into the product, and then on the two-color machine, the product is transferred to the cavity corresponding to another injection cylinder by turning the mold. This part serves as a plug-in, and another TPE material is injected into the plug-in to form an integrated dual-material product.
The injection molding machine has dual cylinders and dual mold cavities. The injection process is to produce two materials at the same time. The product in only one mold cavity enters the next mold cavity as an insert.
A portion of one material is molded on an injection machine, the part is placed as an insert into another mold, and both materials are injected. The methods for overmolding (including glue) of TPE materials include physical button methods and chemical methods. The physical button method mainly relies on tapping the thread on the roller surface of the buckle design, and then coating it with a second layer of material to achieve coating (glue). The characteristic of materials made using this method is that the physical connection parts have strong adhesion and the physical connection parts have very little adhesion. Chemical methods are based on the molecular affinity and chemical bonding between two materials. These two materials combine to form a single ingredient, two or even multiple.
Physical fasteners and chemical bonding methods are often used together in practical applications, but chemical bonding between two TPE materials is a more reliable, design-first method with a higher degree of freedom. This strong chemical bond includes the penetration, mutual dissolution, molecular entanglement and penetration of molecules or molecular chains.
Implementing overmolding with TPE materials requires careful consideration of material selection, substrate preparation, mold design, injection molding process parameters, bonding techniques, quality control measures, and testing protocols. By following these strategies and techniques, we can harness the full potential of overmolding with TPE materials to create innovative and high-performance products across various industries.