Introduction to two-color injection molding technology process and mold characteristics

Two-color injection molding technology is also called two-component injection molding technology. This is a technology that uses two plastic materials to mix and inject plastic products. Its technical connotation is actually to use a mold component to shape the shape and form in the mold. Work welding, so the fundamental principle is to plasticize two different plastic materials, and then use molds for welding installation to achieve the purpose of two-color injection molding.

1. Two-color injection molding technology type

1.1 Core rotating two-color injection molding technology

This technology is also known as the two-color injection molding technology of the core mold. The technical principle is to use the injection equipment to inject the first raw material plastic into the small holes of the mold. When it is molded, it will become the first plastic. , And then rotate the mold 180°, and use the same injection equipment to inject the second raw material plastic. After the second plastic is molded, the final encapsulation work is performed, and a basic two-color injection molding work is completed.

The use and operation of this technology is relatively simple. Generally, workers with a little training can operate freely, and it can greatly improve the design freedom of plastic products. At the same time, it can be processed with simple tools.

1.2 Shrink mold core two-color injection molding technology

The shrink mold core two-color injection molding technology mainly uses a hydraulic device to compress the mold. First, under the control of the hydraulic device, the core that can move up and down is pushed to the top ascending position like a piston, and the plastic material is injected. After the first material is solidified, the movable core is controlled to drop, and then Inject another plastic raw material, and then control the hydraulic device to make the core ascend and press, and wait for it to solidify and form.

The plastic products pressed by this technology are initially manufactured, and then the molded plastic parts are taken out for subsequent processing. The operation of this technique is relatively simple, and the timing of the movement of the hydraulic device must be controlled.

1.3 The principle of the two-color injection technology of the rotation of the stripping plate

Before this technology works, the first raw material must be injected. During injection, other parts of the mold are closed, and the injection mold is gradually cut and separated. The rear part of the insert will gradually retreat, but it still exists on the parting plate part, and the mold retreats dynamically , The ejector rod and the pellet rod part of the entire injection molding machine are cooled and fall off after the path, and the first part is completed;

The next step is to carry out the second part of the injection molding operation, which is roughly the same as the first part, but the second injection uses two nozzles to inject at the same time. After it is cured, the two parts are ejected together to complete an injection cycle.

1.4 Core sliding two-color injection technology

The working principle of the core sliding two-color injection technology is to classify the cores into two for use. During the first injection, the used cores are slid to the designated position, and the clamping injection is carried out. The first raw material The plastic is injected into the mold, and the mold is opened once after cooling.

The transmission device slides the first core out, slides the second core to the cavity, and then injects the second plastic. After it is cooled and formed, one injection cycle is completed, and the two composites are combined again. The finished product slides out. This technical model is more suitable for the needs of large-scale two-color injection molded plastic parts.

2. Introduction to the characteristics of the two-color injection molding process

2.1 Two sets of structure of the two-color injection machine

Due to the influence of the purpose of making the product, the two-color injection molding machine needs to be equipped with two identical plastic injection devices. This is not only the requirement of the process, but also the ability to be able to rotate.

In addition to the same structure, the two injection devices with the same specifications also need to have the same functions. During injection molding, the raw material temperature, injection pressure, and injection rate of the two sets of equipment can be adjusted consistently, so that the injection molded plastic products All indicators of the company are maintained at a consistent level, and then related fusion and welding work is carried out. If the parameters of the two sets of equipment are inconsistent, try to adjust to a consistent level.

2.2 The machine structure difference between two-color injection molding components and ordinary injection molding components

Due to the unique characteristics of the plastic products produced by the two-color injection molding components, there are some obvious differences in the mechanism settings of the machine and ordinary injection molding materials.

First of all, the temperature of the melt used in the two-color injection molding component is higher. Compared with the ordinary injection component, there is a certain gap. It requires a high temperature to maintain the ability to operate and flow in the mold; secondly, the injection pressure is also higher, not only because of the use of They are two different plastic raw materials. To press and weld them, strong pressure is needed to fuse them, and they are designed to overcome the huge resistance of the molten material flowing in the mold to ensure the smooth progress of injection molding.

2.3 Material parameter setting of two-color injection molding technology

Two-color injection molding technology uses two different materials for the production of plastic products. Therefore, materials need to be considered before injection molding. Not only must the quality standards of the selected materials be considered, but also the temperature, pressure and other parameters of the materials during injection molding. control.

Since the mold used in two-color injection molding technology is different from that of ordinary injection molding, this requires two-color injection molding technology material parameters to have a higher melt temperature to ensure that the melt does not solidify before the injection is completed. At the same time, the injection device must be used to control the pressure of the raw material so that it can reach all parts of the mold smoothly, so as to achieve the purpose of injection molding.

3. Two-color injection molding products and mold design points

3.1 Structural characteristics of two-color injection molded products

The structure of two-color injection molded products is very different from that of ordinary plastic products. Due to the use of two different materials for injection molding, the products have two different properties and characteristics, which are fundamentally different from ordinary injection molded products; Before injection molding, a meticulous two-color injection molded product structure design is required, and the compatibility characteristics of the two materials should be fully considered.

Combine the function and use environment of the plastic product to design the mixing ratio and connection method of the two materials, analyze the complexity of the process in detail, and consider the design of the use strength, so that the two-color injection product can meet the relevant material standards And requirements.

3.1.1 Choice of two materials

Two-color injection molding technology uses two different materials for injection molding. Therefore, the selection of two different materials is also an important process. Generally, two different colors of plastic are used, which can greatly improve the strength and durability of the injection molded product. At the same time, it is easier to fusion molding. However, products for special purposes may need to take advantage of the extremely different properties of the two materials, which requires solving the problem of the difficulty of fusion of two relatively different materials.

Mainly there will be delamination and shedding, which is a fatal blow to injection molded products. Therefore, it is necessary to carefully consider the shrinkage rate and the different working conditions of the interface, and adjust the proportion of materials used.

3.1.2 Design of the internal structure and shape of the product

The design of the product structure and shape must first be considered from the purpose and purpose of the product, and detailed research is carried out in terms of size and internal structure.

Generally, it is necessary to increase the contact area of the two materials to enhance the firmness. Here, many small grooves and convex grooves can be designed inside the product for inlay and stitching, which achieves the purpose of increasing the contact area of the two materials. , It can better improve the strength and service life of the product during injection molding, and enhance the practicability.

3.2 Rotary mold two-speed injection mold

This kind of mold requires different considerations in the molding part. First, the concave-convex grooves of the two injection molds need to be carefully designed to ensure that they can be tightly connected during the butt joint. At the same time, when the demolding mechanism is designed, the second injection is required to perform the demolding work. Different injection molding methods need to be differentiated in detail. After the vertically rotating injection machine is demolded, the product is ejected to complete the related operations. However, the ejection of the injection machine cannot be used to eject the mold and the hydraulic device is required for demolding. mold.