Two-color injection molding technology and its development

Time：2021-07-19 11:37:54 / Popularity： / Source：

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 shape and to weld molding work in mold. Therefore, basic principle is to plasticize two different plastic raw materials, then use mold for welding installation to achieve purpose of two-color injection molding.

Two-color injection molding technology process and technology type

Core rotating two-color injection molding technology

This technology is also known as two-color injection molding technology of core mold. Its technical principle is to first use injection equipment to inject the first raw material plastic into small holes of mold. When it is molded, it will become the first plastic. Then rotate mold 180°, use same injection equipment to inject second raw material plastic. After second plastic is molded, final encapsulation work is performed, and a basic two-color injection molding work is completed. Use and operation of this technology is relatively simple. Generally, workers with a little training can operate freely, it can greatly improve design freedom of plastic products. At the same time, it can be processed with simple tools.

Shrink mold core two-color injection molding technology

Shrink mold core two-color injection molding technology mainly uses hydraulic devices to compress mold. First, under control of hydraulic device, core that can move up and down is pushed to top ascending position like a piston, plastic material is injected. After the first material is solidified, movable core is controlled to drop, then another plastic material is injected, hydraulic device is controlled to make core rise and press. When it is solidified and formed, plastic product pressed by this technology is initially completed, then formed plastic part is taken out for subsequent processing. Operation of this technique is relatively simple, timing of movement of hydraulic device must be controlled.

Principle of two-color injection technology with rotating stripping plate

Before this technology works, the first raw material must be injected. During injection, the other parts of mold are closed, injection mold is gradually cut and separated. Rear part of insert will gradually retreat, but it still exists on parting plate part, and mold retreats dynamically. Ejector rod and pellet rod part of entire injection molding machine are cooled and fallen off, the first part is completed; second part of injection molding operation is carried out in next step, which is roughly same as the first part, but second injection uses two nozzles to inject at the same time. After it is cured, two parts are ejected together to complete an injection cycle.

Core sliding two-color injection technology

Working principle of core sliding two-color injection technology is to classify cores into two for use. During the first injection, slide used core to designated position to perform clamping and injection work. Inject the first raw material plastic into mold. After cooling, mold is opened once, transmission device slides the first core out, slides second core to cavity, then performs the second injection of plastic. After it is cooled and formed, an injection cycle is completed, two synthesized products are then slid out. This technical model is more suitable for needs of large-scale two-color injection molded plastic parts.

Introduction to characteristics of two-color injection molding process

Two sets of structure of two-color injection machine

Due to influence of purpose of making product, two-color injection molding machine needs to be equipped with two identical plastic injection devices. This is not only requirement of process, but also ability to be able to rotate. In addition to same structure, two injection devices with same specifications also need to have same functions. During injection molding, raw material temperature, injection pressure, and injection rate of two sets of equipment can be adjusted consistently, so that indicators of plastic products injected are maintained at a consistent level, then related fusion and welding work can be carried out. If parameters of two sets of equipment are inconsistent, try to adjust to a consistent level.

Machine structure difference between two-color injection molding components and ordinary injection molding components

Material parameter setting of two-color injection molding technology

Two-color injection molding technology uses two different materials for production of plastic products. Therefore, materials need to be considered before injection molding. Not only must quality standards of selected materials be considered, but also temperature, pressure and other parameters of materials during injection molding. control. Since mold used in two-color injection molding technology is different from that of ordinary injection molding, it requires use of two-color injection molding technology material parameters to have a higher melt temperature to ensure that melt does not solidify before injection is completed. At the same time, injection device must be used to control pressure of raw material so that it can reach all parts of mold smoothly, so as to achieve purpose of injection molding.

Two-color injection molding products and mold design points

Structural characteristics of two-color injection molded products

This technology is also known as two-color injection molding technology of core mold. Its technical principle is to first use injection equipment to inject the first raw material plastic into small hole of mold. When it is molded, it will become the first plastic. Then rotate mold 180°, use same injection equipment to inject second raw material plastic. After second plastic is molded, final encapsulation work is performed, and a basic two-color injection molding work is completed. Use and operation of this technology is relatively simple. Generally, workers with a little training can operate freely, it can greatly improve design freedom of plastic products. At the same time, it can be processed with simple tools.

Choice of two materials

Two-color injection molding technology uses two different materials for injection molding. Therefore, selection of two different materials is also an important process. Generally, two different colors of plastic are used, which can greatly improve strength and durability of injection molded product. At the same time, it is easier to fusion molding. However, products for special purposes may need to take advantage of extremely different properties of two materials, which requires solving problem of difficulty of fusion of two materials with larger differences.
Mainly there will be delamination and shedding problems, which is a fatal blow to injection molded products. Therefore, shrinkage rate and different interface conditions need to be carefully considered, proportion of materials used must be adjusted.

Design of internal structure and shape of product

Design of product structure and shape must first be considered from purpose of product, detailed research is carried out in terms of size and internal structure. Generally, it is necessary to increase contact area of two materials to enhance firmness. Here, many small grooves and convex grooves can be designed inside product for inlay and stitching, which achieves purpose of increasing contact area of two materials, can better improve strength and service life of product during injection molding, enhance practicability.

Rotary mold two-speed injection mold

This kind of mold requires different considerations in molding part. First, concave-convex grooves of two injection molds need to be carefully designed to ensure that they can be tightly connected during butt joint. At the same time, when demolding mechanism is designed, demolding work needs to be carried out after second injection, and different injection molding methods must be distinguished in detail. After vertically rotating injection machine is demolded, product is ejected to complete related operations. However, demolding situation that cannot be ejected by injection machine needs to be demolded by a hydraulic device.

In conclusion

In summary, two-color injection molding technology has been developed over many years, but it has only been gradually valued and applied in recent years, because finished products produced by it have good adaptability to use environment, and production efficiency is extremely high. Different actual requirements can be well met, so it is gradually being widely used, it has good economic benefits in medical industry and other fields, and it is a technology with great development potential.

Gud Mould Industry Co., Ltd