Two-color mold: a mold in which two kinds of plastic materials are injected on the same injection molding machine and molded in two times, but the product is molded only once. Generally, this molding process is also called double injection molding or over mold, which is usually completed by one set of molds and requires a special two-color injection molding machine.  insert mold: two kinds of plastic materials are not necessarily injected on the same injection molding machine and are molded in two times; After the product is taken out of a mould , then put it into another mold for second injection molding. Therefore, in general this molding process is usually completed by 2 sets of molds, without the need for a special two-color injection molding machine. •  1. The two shapes of Cavity are different, producing one product respectively. The two shapes of Core are exactly the same.  •  2. The core and cavity side of the over mold must be matched after rotating 180 o at the center. This check must be done before production.  •  3. The minimum distance of ejector bar should be 210 mm. The number of ejector bar must be appropriately increased for bigger mould. In addition, because the ejector bar attached to the injection molding machine is not long enough sometimes, we must design a lengthened ejector bar on the over mold, and the ejector bar grows 150mm from the bottom plate of the mold base.  • 4.Two locating rings must be designed on the bottom plate of the core side.  •  5.The nozzle of the three-plate mold should be designed to automatically demould. the demoulding of the soft material runner should be reliable.  • 6. The depth of the front SPRUE shall not exceed 65mm. The distance from the top of the upper side (big nozzle) SPRUE to the center of the over mold base is not less than 150 mm.  • 7. When designing the CAVITY for the second injection molding, in order to prevent the CAVITY from crushing the molded product for the first time, part of the cavity can be designed clearance. However, the strength of each sealing position must be carefully considered, i.e. whether the plastic will deform under large injection pressure during injection molding, resulting in the possibility of flash in the second injection molding.  • 8. During injection molding, the product size of the first injection molding can be slightly larger, so that it can be pressed more tightly with another CAVITY during the second molding to achieve the good sealing.  • 9, Note that in the second injection molding, will the flow of plastics crush the first molded product to deform its glue position? If this is possible, be sure to find ways to improve.  • 10. Before closing over mold,  check whether the cavity side slider or lifter will reset first and crush the product? After the A and B plates are closed first, the SLIDER or LIFET of the cavity can be return to its position • 11. The cooling pipe arrangements for the two cavities and CORE shall be as enough as possible, balanced and identical.  • 12. the most cases involve injecting the hard part of the product first and then injecting the soft part of the product. Because soft material is easy to deform. 13. In order to "stick" the two plastics more tightly, the "stickiness" between the materials and the roughness of the mold surface should be considered. Two-color injection molding has special TPU ? The smoother the surface of the mold, the tighter they "stick."