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Design Essentials and Development Applications of Two-Color Injection Molding

Two-color injection molding refers to the molding process of injecting two different materials into the same mold to create a part made of two materials. Some of the two materials are of different colors, and some are of different hardness, thus improving the appearance and assembly performance of the product. Two-color molding injection molding is a method of injecting two different colors of the same plastic into two barrels for plasticization, and then injecting them simultaneously or sequentially through the same nozzle. Using two injection molding machines or two-color injection molding machines, various mixed-color pattern products can be produced, as well as products with obvious color separation.

Design Points of Two-Color Injection Molding

Molding part

The molding part of the double shot moulding is basically the same as the general injection mold, but the two convex molds at two positions should be consistent, and the concave mold should match well with the two convex molds. Generally, the plastic products of this type of molding are relatively small.

Demoulding mechanism

Since the two-color plastic products can only be demolded after the second injection, the demolding mechanism on a single injection device will not work. For a horizontally rotating injection molding machine, the ejection mechanism of the injection molding machine can be used for demoulding, while for a vertically rotating injection molding machine, the ejection and demoulding mechanism can be set on the rotating table.

Gate system

As it is a twin shot moulding, the gate system is divided into a gate system for the first injection and a gate system for the second injection, which come from two injection molding devices respectively.


Since the molding method of dual injection moulding is quite special and requires mutual coordination and coordination, the dimensions and accuracy of the two sets of mold guiding devices should be the same. For horizontally rotating injection molding machines, the mold closing height should be consistent, the centers of the two sets of molds should be on the same rotating radius and 180 degrees apart. For vertically rotating injection molding machines, the two sets of molds should be on the same axis.

Development and Application of Two-Color Injection Molding

From the characteristics and applications of multi-color injection molding and two-material co-injection molding, it can be seen that there is a trend to gradually replace traditional injection molding processes in the future. The molding technology not only improves the precision of the injection molding process and provides high-difficulty process technology, but also expands the scope of the injection molding process. Innovative injection equipment and processes can only cope with the increasing demand for diversified, high-quality, and high-added-value products.

Double injection moulding is now widely used in almost all plastic fields such as electronic products, power tools, medical products, home appliances, and toys, and the development of two-color mold making and molding, as well as the research and development of two-color and multi-color injection molding machines and raw materials, has also developed rapidly.

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