Co-Injection in Action
Historically, co-injection workcells have been highly specialized dedicated systems with high capital cost to start with. Now there are new solutions coming on the market, which will allow molders and moldmakers to create co-injection systems at a radically different cost because they are now able to use their installed workcell base and standard molds for the solution.
Co-injection is the process of injecting two resins simultaneously through a single gate to form a multi-layer structure. This advanced molding technique has been used for a couple of decades with some success in specialized applications like ketchup containers, stadium beer bottles and medical vials. However, recently there has been a re-emergence of interest in co-injection technology spurred on by the development of new resins, barrier systems, controls and hardware technologies.
Moldmakers need to be aware of how different gating technology can affect their customers when designing a hot runner system into a mold.
Understanding the effects of injection on the core, slide and associated components is critical to selecting the best side-action methods for a given application. This first of two articles will discuss the basic physics underlying all side-actions.
Both copper and graphite provide approximately the same end result, so it is important for a shop to consider the advantages and disadvantages of each material in order to discover what would work best in their shopfloor environment.