Sometimes more than one plastic is needed to manufacture a part. Either two types of material, two colors, or both. When this Is required, co-injection may be the solution. Co-injection is the process in which two separate materials are used to create a product. The substrate is the first material and the over-mold or second shot finishes the part.
Co-Injection as a general term can denote different processes. Atlantis specifically uses rotary co-injection. This technology allows both materials to be injected in two halves of the mold simultaneously. While the substrate is being injected in the top half of the mold, the second shot is being injected in the bottom half of the mold. The top half is injected through the normal sprue nozzle and the co-injection is delivered via a side or top mounted sprue nozzle.