Introduction to Two-color Injection Molding Technology and Mold Characteristics

Today, consumer products come in a myriad of styles, demanding not only aesthetic appeal and exquisite design, but also swift adaptation to market demands. Designers typically employ different materials in various parts of consumer products, depending on their intended use, to cater to specific environmental needs, thereby extending product lifespan and enhancing both aesthetics and practicality.

This practical design requirement will undoubtedly lead to the complexity of production technology. The dual-material injection molding process emerged in response to this trend. Generally, dual-material products can be manufactured using a single-color injection molding machine, and basically, one injection molding machine is sufficient. However, the post-processing steps are quite time-consuming and complex, directly affecting the quality of the product, and the overall production cost is not economical. In addition to making corresponding modifications to the injection molding machine, the skill of mold design is the soul of the entire technology. The mold achieves the effect of simultaneously injecting different materials by rotating and shifting.

The two-color injection molding technology, also known as dual-material injection molding technology, is a technique for producing plastic products by mixing and injecting two different plastic materials. Its technical essence lies in using a mold assembly to shape the form and perform welding within the mold for molding. Therefore, the fundamental principle is to plasticize and mold two different plastic materials, and then use the mold for welding and assembly to achieve the goal of two-color injection molding.

1. Types of two-color injection molding technology

1.1 Core Rotating Two-Color Injection Molding Technology

This technology is also known as the mold-rotating dual-color injection molding technology. Its technical principle involves first using an injection device to inject the first type of raw material plastic into small holes in the mold, which will become the first type of plastic after molding. Then, the mold is rotated 180°, and the same injection device is used to inject the second type of raw material plastic. After the second type of plastic is molded, the encapsulation work is carried out, and a basic dual-color injection molding process is completed.

The use and operation of this technology are relatively simple, and generally, workers with a little training can operate it freely. Moreover, it can greatly enhance the design freedom of plastic products, and processing can be carried out with simple tools.

1.2 Shrink mold core-type two-color injection molding technology

The shrink mold core-type two-color injection molding technology primarily utilizes hydraulic devices to perform compression operations on the mold. Firstly, under the control of the hydraulic device, the movable core, which can move up and down like a piston, is pushed to the top position. Then, plastic raw materials are injected. After the first type of raw material solidifies, the movable core is controlled to descend, and another type of plastic raw material is injected. Subsequently, the hydraulic device is controlled to make the core ascend and press, until it solidifies and takes shape. Zhenye Injection Molding Consulting focuses on improving and enhancing injection molding factories.

The preliminary production of plastic products using this technology is completed. Afterwards, the molded plastic parts are taken out for subsequent processing and manufacturing. This technical operation is relatively simple, but it is necessary to control the timing of the hydraulic device's movement.

1.3 Principle of rotational dual-color injection technology for removable plates

Before this technology is put into operation, the injection of the first raw material must be carried out first. During injection, the other parts of the mold are clamped together. As the mold undergoes injection, it gradually undergoes cutting and separation. The rear part of the insert will gradually retreat, but it still remains on the stripper plate. Meanwhile, the mold dynamically retreats, passing through the ejector pin and stripper pin of the entire injection molding machine, and then cools and detaches. The first part is thus completed;

The next step involves the injection molding operation for the second part, which is largely similar to the first part. However, for the second injection, two nozzles are used to inject simultaneously. After curing, the two parts are ejected together, completing one injection molding cycle.

1.4 Core sliding dual-color injection technology

The working principle of the core sliding dual-color injection technology is to categorize the cores for use in two stages. During the first injection molding, the core to be used is slid to a designated position, where mold clamping and injection molding are carried out. The first type of raw material plastic is injected into the mold, and after cooling, the mold is opened at one time.

The transmission device slides the first core out and the second core into the mold cavity, followed by the second injection of plastic. Once it cools and forms, a complete injection molding cycle is completed. The finished product, combining the two parts, is then ejected. This technical approach is more suitable for the needs of large two-color injection molded plastic parts.

Label: Two-color mold injection molding