The difference between two-color molding and overmolding
A. Two-color mold:Two kinds of plastic materials are injection-molded on the same injection molding machine, and molded in two parts, but the product only molds once. Generally, this molding process is also called double-material injection molding, usually completed by a set of molds, and requires a special two-color injection molding machine.
B. Overmolding mold (overmolding): The two plastic materials are not necessarily injection molded on the same injection molding machine, and are molded in two parts; the product is taken out from a set of molds and then placed in another set of molds. The second injection molding. Therefore, in general, this molding process is usually completed by two sets of molds, without the need for a special two-color injection molding machine.
Two-color mold and plastic mold overview:
In the design of the rubberized mold, attention should be paid to the positioning of the hard rubber parts. It is necessary to seal the rubber and have a reverse slope on the rubber parts to prevent deformation of the rubber.
Two-color molds are becoming more and more popular on the market today. In this process, the appearance of the product can be more beautiful, and it is easy to change colors without spraying, but the cost is high and the technical requirements are high.
1. The two shapes of Cavity are different, and one product is separately formed.
The two shapes of the Core are exactly the same.
2. The front and back molds of the mold must be aligned after being rotated 180o in the center. This check must be done during design.
3. Pay attention to the position of the thimble hole, the minimum distance is 210mm. Large molds must be appropriately increased in the number of top stick holes. Moreover, since the ejector pin attached to the injection molding machine itself is not long enough, the ejector pin must be designed in our mold, and the thimble grows about 150 mm from the base of the mold base.
Two positioning rings must be designed on the bottom plate of the back mold.
4. The total thickness of the front mold panel plus the A board should not be less than 170mm. Please review the other reference data for this type of injection molding machine, such as maximum die thickness, minimum die thickness, and top hole distance.
5. The nozzle of the three-plate mold can be designed to automatically release the mold. Pay special attention to whether the release action of the soft glue nozzle is OK*.
6. The depth of the front side SPRUE should not exceed 65mm. The distance from the top of the upper side (large nozzle) SPRUE to the center of the mold blank is not less than 150 mm.
7. When designing the second injection molding of CAVITY, in order to avoid CAVITY inserting (or rubbing) the first molded product glue position, you can design a part to avoid the air. However, the strength of each sealant must be carefully considered. That is, in the injection molding, will the plastic be deformed under the large injection pressure, which may cause the possibility of the second shot?
8. When injection molding, the size of the first injection molding product can be slightly larger, so that it can be pressed tighter with another CAVITY in the second molding to achieve the function of sealing.
9. Note that in the second injection molding, will the flow of the plastic impulsive the first molded product to deform the glue position? If this is possible, be sure to find ways to improve.
10. Before the A and B plates are closed, pay attention to whether the front die Slider or Lifter will reset first and crush the product? In this case, it is necessary to find a way to clamp the A and B boards first, and then the SLIDER or LIFET of the front mode can be reset.
11. The water transport layout of the two CAVITY and CORE is as full as possible and balanced.
12.99% of the cases are the hard rubber part of the injection molded product first, and the soft rubber part of the injection molded product. Because the soft rubber is easy to deform.
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