What is the difference between two-color mold and overmold mold

Two-color mold: The two plastic materials are injected on the same injection molding machine, and the molding is divided into two times, but the product is only ejected once. Generally, this kind of molding process is also called two-component injection molding, which is usually completed by a set of molds and requires a special two-color injection molding machine.
Overmolding mold (secondary molding): Two plastic materials are not necessarily injected on the same injection molding machine, and are molded in two parts; after the product is taken out from one set of molds, it is put into another set of molds for the second time Injection molding. Therefore, this molding process is usually completed by two sets of molds, without the need for a special two-color injection molding machine.

Overview of two-color molds and overmolding: In the design of overmolding, attention should be paid to the positioning of the hard rubber parts. It needs to be able to seal the glue and have reverse slope holes on the rubber parts to prevent deformation of the glue. Two-color molds are becoming more and more popular in the market. This process can make the appearance of the product more beautiful, easy to change the color without spraying, but it is expensive and requires high technical requirements.

1. The two shapes of Cavity are different, and one product is molded separately. The two shapes of Core are exactly the same.
2. The front and back molds of the mold must be aligned after rotating 180o from 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 appropriately increase the number of top stick holes. Moreover, because the ejector pin attached to the injection molding machine itself is not long enough, we must design an extended ejector pin in our mold. The ejector pin grows about 150mm 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 A plate cannot be less than 170mm. Please carefully check the other reference data of this type of injection molding machine, such as the maximum mold thickness, minimum mold thickness, and top rod hole distance.
5. The nozzle of the three-platen mold should be designed to automatically release the mold. Pay special attention to whether the demoulding action of the soft glue nozzle is possible*.
6. ​​The depth of the front SPRUE should not exceed 65mm. The distance from the top of the SPRUE on the upper side (large nozzle) to the center of the mold base is not less than 150mm.
7. When designing the CAVITY for the second injection, in order to avoid the CAVITY inserting (or scratching) the glue position of the first molded product, a part of the gap can be designed. However, the strength of each sealing position must be carefully considered, that is, during injection molding, will the plastic be deformed under high injection pressure, which may lead to the possibility of cracking in the second injection?
8. When injection molding, the product size of the first injection molding can be slightly larger, so that it can be pressed tighter with another CAVITY during the second molding, in order to achieve the function of sealing glue.
9. Pay attention to whether the flow of the plastic impulses the product that has been formed the first time and deforms the glue position during the second injection? If this is possible, we must find ways to improve it.
10. Before clamping the A and B plates, pay attention to whether the front mold Slider or Lifter will reset first and crush the product? In this way, we must find a way to close the molds on the A and B boards first, and then the SLIDER or LIFET of the front mold can be reset.
11. The water transportation arrangement of the two CAVITY and CORE is as sufficient as possible, and the balance is the same.

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