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What problems should be paid attention to in the design of two-color molds

update:26-12-2020
abstract:

A two-color mold is a mold in which two plastic materia […]

A two-color mold is a mold in which two plastic materials are injected twice on the same injection molding machine, but the product is produced only once. Next, Aofu Plastics will tell you what problems should be paid attention to in the design of two-color molds.

1. The two shapes of the front mold are different, forming a product respectively. The two shapes of the latter mold are exactly the same. (Note: If there is a difference, the front slider should be used to ensure that the rear slider is consistent.)

2. The front mold of the mold must be rotated 180 times in the center and must be consistent with the back mold. This must be noted in the design.

three. When designing, please carefully check the parameters of the two-color injection molding machine, such as the maximum mold thickness, the minimum mold thickness, and the distance between the ejector holes, etc.

4. The nozzle design of the three-piece mold should be able to demould automatically. Special attention should be paid to the reliability of the ejection action of the soft glue nozzle.

5. When designing the cavity for the second injection, in order to avoid the cavity inserting (or scratching) the glue position of the product that has been formed the first time, a part of the space 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?

6. 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 during the second molding, in order to achieve the function of sealing glue.

7. Pay attention to whether the flow of plastic will impulse the product that has been formed the first time and deform the glue position during the second injection? If this is possible, we must find ways to improve it.

8. The water transportation arrangement of the two cavities and cores is as sufficient as possible, and balanced and the same.

9. In 99% of cases, the hard rubber part of the injection molded product is first, and then the soft rubber part of the injection molded product. Because soft glue is easy to deform.

10. In order to make the two plastics "sticky" tighter, it is necessary to consider the "stickiness" between the materials and the roughness of the mold surface. Two-color injection molding has special TPU; and the smoother the mold surface, the tighter they "stick".