Simple Two - Color Mold

1.1 Product Description

Figure 1 - 1 shows the two - color product drawing of a bottom cover part. Its external dimensions are φ48mm x 13.3mm. The green part is the first - color ABS material (hard plastic), and the orange part is the second - color TPU material (soft plastic). This part has a relatively simple structure and small size, belonging to the most basic and simplest two - color product. The mold is required to produce 2 + 2 cavities per mold.

[A two - color product drawing of a bottom cover part](Figure 1 - 1)

1.2.1 Parting and Ejection Direction

In the early stage of mold design, it is necessary to first analyze the ejection direction of the plastic product and set the parting line. Due to the simple structure of this product, the parting line can be easily determined as the maximum outer contour line of the product, as shown in Figure 1 - 2. The second - color part of the product can be completely formed in the fixed - mold cavity.

This product fully complies with the basic principle of simple two - color mold design: the product shapes in the fixed mold are different, while the product shapes in the moving mold are exactly the same. (Note: The basic principle of simple two - color mold design mentioned above is defined according to ordinary simple two - color products, that is, the moving - mold cores of the first - color product and the second - color product are the same, while the fixed - mold molding parts are different.)

1.2.2 Gate Setting

The key point of this two-color mold design lies in how to design the position and form of the second-color soft glue gate. According to the product appearance requirements and considering the production cost, the first-color ABS material adopts a fine water port tip gate, and the glue is injected from both sides of the product, as shown in Figure 1-3. Since the second-color TPU soft glue will be used as the outer surface of the product, considering the aesthetics of the product, the second-color material adopts a side gate for glue injection on the side of the product. The gate marks are located in the non-appearance area of the product, and auxiliary runners are set on the opposite side to facilitate subsequent ejection, as shown in Figure 1-4 .      

1.2.3 Product Ejection

The product is relatively simple. The moving mold part uses auxiliary runners on both sides of the soft glue for ejection to take out the product, and direct mold ejection can be achieved by using round ejector pins, as shown in Figures 1-5. After the first-color hard glue ABS is injection-molded, the rear mold rotates 180°, and the second-color soft glue TPU is injection-molded. Then, the ejector pins eject the auxiliary runners together with the product, as shown in Figure 1- 6