Five mins to understand what is 2K injection molding?

Aug 12, 2022

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Five mins to understand what is 2K injection molding?

Double Injection Plastic Parts 1

In the injection mold industry, a 2K injection molding(double injection) refers to a mold that produces products with two colors of plastic at the same time.

Two-color mold: a mold in which two plastic materials are injected on the same injection molding machine and molded in two times, but the product is only released once. Generally, this molding process is also called double-material injection molding, which is usually completed by one set of molds and requires a special two-color injection molding machine.

Overmolding: The two plastic materials are not necessarily injected on the same injection molding machine, but are molded in two times; after the product is taken out from one set of molds, it is put into another set of molds for the 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.

The two-color mold has become popular in the market, and because this process can make the appearance of the product more beautiful, it is easy to change the color without spraying, and it will definitely be a market trend.

Double Injection Molds Combine

2K mold design requires basics.

According to the problems encountered in the design and production of the current two-color mold, it is summarized in the following, and I hope everyone will follow it in the future design work. For the unfinished parts, please follow the "Notes for New Model Design".

1. The two shapes of Cavity are different, and one product is formed separately.

The Core's two shapes are exactly the same.

2. After the front and rear molds of the mold are rotated 180° from the center, they must be matched. This check action must be done at design time.

3. Pay attention to the position of the top stick hole, the minimum distance is 210mm. For large molds, the number of top stick holes must be appropriately increased. In addition, since the top rod attached to the injection molding machine itself is not long enough, we must design a longer top rod in our mold, and the top rod grows about 150mm from the bottom plate of the mold base.Two positioning rings must be designed on the bottom plate of the rear mold.

4. The total thickness of the front mold panel plus A board should not be less than 170mm. Please carefully check other reference data of this type of injection molding machine, such as the maximum die thickness, the minimum die thickness, the distance of the top bar hole, etc.

5. The nozzle of the three-plate mold should preferably be designed to automatically release the mold. Special attention should be paid to whether the release action of the soft glue nozzle is reliable.

6. The depth of the front SPRUE should not exceed 65mm. The distance from the top of the upper side (large nozzle) SPRUE to the center of the mold base is not less than 150mm.

7. When designing the CAVITY for the second injection, in order to prevent the CAVITY from inserting (or scratching) the glue position of the product that has been molded for the first time, a part of the cavity can be designed. However, the strength of each sealing position must be carefully considered, that is: in the injection molding, is there a possibility that the plastic will be deformed under the large injection pressure, which may lead to the possibility of a sharp edge in the second injection molding?

8. When 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 in the second molding to achieve the effect of sealing.

9. Note that during the second injection, will the flow of the plastic impulsive the product that has been molded for the first time, causing its glue position to be deformed? If this is possible, there must be a way to improve it.

10. Before the A and B plates are closed, 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.