What is encapsulation?

Encapsulation is also known as overmolding. Compared with the bonding of third-party materials, the overmolding process makes the process faster and more cost-effective, and has been widely used in plastic design.

There are three types of secondary injection molding: insert molding, double injection molding, and co-injection molding.

Secondary injection molding

Insert molding: It is most commonly used to mold soft elastomers into hard plastics. Insert molding is the most economical method for overmolding. In the design of the insert, the hard segment has been divided into tools in advance, and then the soft material is injected.

Elastomers are adhesives, which can be mechanical locks, chemical and other methods. In order to achieve chemical bonding, the elastomer must be sufficiently heated to melt the surface of the hard segment to achieve chemical bonding.

Overmolding: This overmolding process requires two injection molding machines. The hard segment is injected first, and then guided by the elastomer mold to the injection molding machine to complete the injection process of the hard segment into the elastomer. The hot matrix is usually a semi-solid, gel state. These molds can be designed and shaped to protrude from the side of the hard segment on the substrate. This can achieve stable mechanical coupling.

Co-injection molding: In co-injection molding, when the hard substrate and the elastomer are injected into the same mold, the compatibility between the materials is essential and must be carefully controlled.

Co-injection is very expensive and difficult to control; it is the least used compared to the other two methods. However, since the hard and soft substrate elastomers are in a completely molten state, it provides the best adhesion between soft and hard parts, and the quality of the molded parts is also the best.