Haojun Mould Sharing: The difference between plastic overmold and two-color mould


Overview of two-color molds and overmolded molds: In the design of overmolded molds, attention should be paid to the positioning of hard rubber parts. It must be sealable and have reverse-slope holes on the rubber parts to prevent deformation of the plastic. Two-color molds are becoming more and more popular in the market. , Because of this process, the appearance of the product can be more beautiful, easy to change the color without spraying, but the cost is expensive and the technical requirements are high. Haojun Mould now talk about the difference between these two moulds:

The difference between plastic overmold and two-color mold:

1. Overmolding (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 processing Two-shot injection molding. Therefore, this kind of molding process is usually completed by two sets of molds, and no special two-color injection molding machine is required. The mold structure is the same as that of the single-color injection mold, and it is mainly controlled by adjusting the flow rate of the injection parameters. The binding point. The encapsulation mold is mainly soft rubber encapsulated hard rubber. The soft rubber is usually made of artificial rubber, TPU, TPR and other rubber materials, and the hard rubber can be ABS, PC, PP, etc.

2. Two-color mold: a mold where two plastic materials are injected on the same injection molding machine in two moldings, 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. The two-color mold can combine two resins with different characteristics and colors into a single two-color product, which can reduce the assembly and post-processing engineering of the molded product. Save the cost of melting and printing, increase the beautiful visual effect of the product, and enhance the grade and added value of the product. Not only has the function of anti-skid and increased friction, the flexible resin material makes it more ergonomic and feels better. The two-color injection product has high quality stability, easy control of product deformation, short molding cycle and high output. The loss is 7% lower than that of overmolding, and the product manufacturing cost can be 20%-30% lower than that of overmolding.

The characteristics of the two-color mold are:

1. The two shapes of the female mold are different, and one product is formed separately, while the two shapes of the male mold are exactly the same.

2. After the front and back molds of the mold are rotated 180° from the center, they need to be anastomosed. This checking action is required during design, and this point has higher requirements for the positioning and processing of the mold base.

3. The total thickness of the front mold panel plus A board cannot be less than 170mm. Please carefully check the other reference data of this type of injection molding machine, such as the thickness range of the mold and the distance of the KO hole.

4. It is recommended that the nozzle of the three-plate mold can be designed to automatically release the mold. Pay special attention to whether the demoulding action of the soft glue nozzle is possible*.

5. When designing the master mold for the second injection, in order to avoid the second master mold inserting (or scratching) the glue position of the product that has been formed last time, a part of the avoidance can be designed. However, it is necessary to carefully consider the strength of each sealing position, that is, during injection molding, whether the plastic will deform under the large injection pressure, which may cause the possibility of cracking in the secondary injection molding.

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 male mold during secondary molding, so as to achieve the function of sealing glue.

7. Pay attention to whether the flow of plastic impulses the product that has been molded last time and deforms the glue position during the second injection molding process? If this is possible, we must find ways to improve it.

8. Before closing the A and B plates, pay attention to whether the front mold slider or inclined top will reset first and crush the product? In this way, it is necessary to find a way to close the molds on the A and B plates first, and then the slider or the inclined top of the front mold can be reset.

9. The water transportation arrangement of the two female molds and the male mold is as sufficient as possible, and is balanced and the same.

In 10.99% of cases, the hard rubber part of the injection molded product first, and then the soft rubber part of the injection molded product. Because soft glue is easy to deform.