Two-color mold: Two kinds of plastic materials are injected on the same injection molding machine and are molded twice. However, the product is only used for molds. The molding process is usually called two-shot injection molding. It is usually completed by a set of molds and requires special Two-color injection molding machine.
Overmolding (Secondary Molding): Two types of plastic materials are not necessarily injected on the same injection molding machine and are molded in two separates; the product is removed from one set of molds and then placed in another set of molds for the second Injection molding. Therefore, the general molding process is usually completed by two sets of molds, without the need for a dedicated two-color injection molding machine.
Overmolding mold (overmold) and two-color mold overview
Secondary molding die in the design should pay attention to the positioning of hard plastic parts, to be reliable sealing plastic and the reverse pitch hole in the plastic parts to prevent the plastic deformation.
Two-color mold is increasingly popular on the market today, in this technology can make the appearance of the product more beautiful, easy to change the color without spraying, but expensive, high technical requirements.
1. The two shapes of Cavity are different, forming one product separately. The two shapes of Core are exactly the same.
2. Mold before and after the mold to the center of rotation 180o, must be consistent. Design must do this check action.
3. Pay attention to the position of the thimble hole, the minimum distance is 210mm. The large mold must increase the number of the top hole. Also, because the ejector attached to the injection molding machine itself is not long enough, we must design an extended thimble in our mold. 150mm left and right bottom plate must be designed on the two positioning ring.
4. The total thickness of the front mold panel plus the A-plate must not be less than 170mm. Please check the other reference data for this type of injection molding machine carefully, for example, the maximum mold-receiving thickness, the minimum mold-container thickness, the top-bar hole distance, etc.
5. The nozzle of the three-plate die can be designed to be able to automatically release the mold. Special attention should be paid to whether the release of the soft glue mouth is reliable.
6. The depth of the front side SPRUE should not exceed 65mm. The distance from the top of the SPRUE on the upper side (big nozzle) to the center of the mold center should not be less than 150mm.
7. In designing a second injection of CAVITY, you may want to design a partially emptying solution to avoid CAVITY being the first to have molded product (or wiping off), but you must consider carefully the strength of each application, : In the injection molding, whether there will be a big injection pressure, the plastic deformation, resulting in the second injection may have approved the possible production Feng?
8. For injection molding, the size of the first injection molded product can be slightly larger so that it can be pressed more tightly with another CAVITY on the second molding to achieve the encapsulation effect.
9. Note that in the second injection, the plastic flow will impulse the first good products have been formed, the plastic deformation? If possible, we must find ways to improve.
10. In the A, B plate clamping, pay attention to the front mold Slider or Lifter will be reset and crush the product? So, we must find ways to make the A, B board first mold, after the front mold SLIDER or LIFET to reset.
11. Two CAVITY and CORE shipping arrangements as full as possible, and balanced, the same.
12. 99% of the case is the first injection of plastic products, plastic parts, plastic injection products and then part of the soft because of deformation.
13. In order to make the two types of plastic 'sticky' tighter, the 'stickiness' of the material and the roughness of the mold surface should be taken into consideration. Two-color injection molding has a special TPU, while the smoother the mold surfaces, they are 'sticky' more tightly.
14. Pay attention to the positioning of the mold before and after; all inserted through the slope of the broken surface as much as possible, to 0.1mm above.