Coinjection makes it possible to recycle plastic parts and post-industrial materials.
Coinjection is an injection molding process where different polymers are injected into the same mold to produce a specific effect. In many cases, the desired effects include changing the physical properties of the polymers or reducing production costs. This process is also known as sandwich molding. There are two types of coin injection processes: machine-based and mold-based. Each type offers its own benefits and specific applications.
The coin injection machine requires the use of two or more processing units. This is considered a cold room process. Molten plastic from each processing unit is forced through a manifold where it is combined and then exited through a single nozzle. By processing plastic in this way, the result is a core product covered by a polymer film.
In-mould co-injection is a hot runner process in which the two molten plastics are kept separate until the last stage. The jets come together when they reach the mould, forming a piece with a double-layer effect. This type of trim is commonly seen on household products, such as toothbrush handles, which have a clear outer surface around a colored core. Although this application is suitable for creating certain aesthetic effects, it is also useful in other ways. Combining a core product with a polymer layer allows manufacturers to create a wide range of different product properties.
The reduced cooling time required in the co-injection process makes this method a practical technique for low temperature core products. By using a lower cost recycled core material coated with a more expensive polymer film, the manufacturer can save on production costs. In a similar arrangement, a strong core material such as glass can be used to add strength and stiffness to a more flexible polymer. In some cases, coin injection molding is combined with a foam core to create products with sound-absorbing properties.
In addition to the obvious benefits of the manufacturing process, coin injection offers advantages from an environmental and consumer standpoint. This process makes it possible to recycle plastic parts and post-industrial materials. These materials are ground and used to form inexpensive cores for injection molded parts. By using recycled materials, you reduce the cost to consumers and eliminate product waste in landfills. The added strength of basic options can also result in more durable and long-lasting products.