Now the ever-changing consumer product models require good looks, fancy design, and also to quickly meet market demand. Designers generally design products for different purposes, in different parts of different materials to meet the needs of a particular environment, and to extend the product life and increase aesthetic and practical purpose. This practical design requirements will undoubtedly lead to the production technology also will be complicated, double color injection molding process is to be born of this trend.

Double color injection molding is make two different color materials injected to one same mold, to make plastic parts presents regular or irregular pattern more-like colors to enhance the plastic parts of practicality and aesthetics.

A two-color product refers to a product consisting of two colors. Note that not two parts are installed together, but they are completed through two injection moldings. The advantage of the product is that the two colors are not easily separated. Two-color products are widely used in articles of everyday use, household appliances, medical equipments etc.

Two-color requires two moulds to achieve two colors. The height of the two moulds must be exactly the same and usually produced with two-color injection molding machine.

1. The two mould cavity shapes are different, form the product respectively, and the two core shapes are exactly the same.
2. The mould core and cavity shall match well after rotate 180 degrees. This inspection must be done during the designing process. When make the design, designer must check this action, as this has very high requirement for mold base positioning process.
3. The three-plate mould gate is preferably designed to be able to release automatically. If inject TPU or TPE material, especially important to pay attention to the gate dropping whether feasible.
4. When design the 2nd color mould, in order to prevent the 2nd mold from inserting (or rubbing) and hurting the product that has been molded by 1st color mould, can leave some space, but need consider the strength of each touching area. That is, whether will get deformation when under a large injection pressure result in the 2nd time injection molding.
5. When molding the products, it’s better to make the 1st color a little bit bigger, so it can fit tighter when put it to the 2nd color mould.
6. At the second injection molding, will the material melt flow impact the 1st color molded product which leads to deformation? If possible, must find a way to improve.
7. Before mould clamping, shall notice the slide or angle lift will crush the product if they reset ahead. It is necessary to find a way to make A and B plate clamp first, then let slide or angle lift reset.
8. The water layout and channels on two cores and cavities need be as full and balanced as possible.
9. 99% of cases, to inject the hard part first, and then inject the soft plastic part as the soft part easily get deformed.

f you don’t have two-color machine but want to product a two-color product, you can produce the internal part or hard part first, and then install it into the second mould do the molding. However, the production cost will be high.