Difference between two-color molds and overmolding molds:

A. Two-color molds: Two plastic materials are injected in the same injection molding machine, molded in two steps, but the product is demolded only once. This type of rubber and plastic product processing is also called three-material injection molding, generally using one set of molds, and requires a professional two-color injection molding machine.

B. Overmolding molds (secondary molding): Two plastic materials are not necessarily injected in the same injection molding machine, molded in two steps; the product is removed from one mold and then placed in another mold for a second injection molding. Therefore, this type of rubber and plastic product processing generally uses two sets of molds and does not require a professional two-color injection molding machine.

Brief description of two-color molds and overmolding molds:

The design of overmolding molds should pay attention to the precise positioning of the hard plastic products, ensuring reliable adhesion and anti-tilt holes on the plastic products to prevent deformation during pulling.

Two-color molds are becoming increasingly popular in the current market. This process can make the product's appearance more beautiful, facilitating color changes without the need for painting, but the construction cost is high, and the technical standards are high.

1. The two shapes of the Cavity are different, each forming one product.

The two shapes of the Core are exactly the same.

2. After the front and rear molds of the mold are rotated 180 degrees around the center, they must match. This check must be performed during the design.

3. Pay attention to the position of the ejector pin holes, with a minimum distance of 210 mm. Large molds need to appropriately increase the number of ejector pin holes. Moreover, because the ejector pins attached to the injection molding machine itself are not long enough, the mold must be designed with extended ejector pins, extending about 150 mm beyond the bottom plate of the mold blank.

Two positioning rings must be designed on the bottom plate of the rear mold.

4. The total thickness of the front mold panel plus the A plate cannot be less than 170 mm. Please carefully check the other reference data of this type and size of injection molding machine, such as the maximum mold thickness, minimum mold thickness, ejector pin hole spacing, etc.

5. The water position of the three-plate mold is best designed to be an automatic demolding action. Pay special attention to whether the demolding action of the soft glue water position is reliable.

6. The depth of the outer SPRUE should not exceed 65 mm. The distance from the top of the upper (large water position) SPRUE to the center of the mold blank is not less than 150 mm.

7. When designing the second injection CAVITY, in order to prevent the CAVITY from scratching (or rubbing) the already formed product glue position, a part of the air gap can be designed. However, the compressive strength of each sealing position must be carefully considered, that is: during injection molding, will deformation of the plastic occur under high injection pressure, resulting in the possibility of flash in the second injection?

8. During injection molding, the size of the product formed by the first injection can be slightly larger, so that it is pressed tighter with another CAVITY during the second molding to achieve the effect of adhesion.

9. Pay attention to whether the fluidity of the plastic during the second injection will unreasonably affect the already formed product, causing the glue position to deform? If there is this possibility, a solution must be found.

10. Before the A and B plates are closed, pay attention to whether the front mold Slider or Lifter will be calibrated first and crush the product? In this way, a method must be found to close the A and B plates first, and then the SLIDER or LIFTER of the front mold can be calibrated.

11. The water inlet layout of the two CAVITYs and CORE should be sufficient, balanced, and consistent.

12. In 99% of cases, the hard part of the product is injected first, followed by the soft part. This is because soft glue is easily deformed.