What is Overmolding?

In recent years, with the development of industrial technology, multi-color (multi-component) plastic injection molding technology has been widely used. The technical development of a two-color machine can be divided into two main technical guidance, and one is represented by European and American enterprises, biased to generality, is in the monochrome injection molding machine based on the addition of relevant configuration to form a two-color machine, its characteristics is a dual-use machine.

Second, represented by Japanese and Taiwan enterprises, biased to specificity, its two-color machine for special models and integration of many customized functions, more suitable for professional mass production of two-color products.

After entering 2000, there were four significant developments in two-color machine technology: large-scale, precision/specialization, multi-injection molding and multi-function, vertical rotation axis.

The development of a multi-component injection molding machine began with the two-color machine. With the increase in product complexity, the demand for three-color or even four-color began to emerge. 

From the technical point of view, the precision of multi-task turntable control is higher than that of two stations, so the manufacturing cost of the machine is relatively high, so it is not necessary to blindly pursue a multi-task multi-color machine, but to choose the most effective scheme according to the product structure demand.

In terms of multi-function development, the realization of the mobile function of the injection molding unit is what makes multi-component injection molding machines have various parts and a flexible production model.

  1. The Definition Of Overmolding

Overmolding refers to the injection of two different materials into the same molds to achieve the molding process of the product formed by two materials. Two kinds of materials have plenty of colors, have plenty of soft and hard is different, and can improve the product’s beauty and performance, such as assembly.

  1. The advantages of Overmolding

① The core material is recycled secondary or low viscosity material, which can reduce residual stress, increase mechanical strength, or produce surface properties.

② Proper combination of coating and core material can reduce residual stress and increase mechanical strength or product surface properties. Can use the cortical material with special surface property or core material, prevent electromagnetic wave interference, high conductance to wait.

③ Automatic production line, high response, high repeatability, greatly reduce the process and human resources product output stability, ensure delivery time, increase the workshop utilization rate, and reduce management costs.

④ Long die life, stable quality, reduce scrap rate.

⑤ According to different use characteristics, the core and cortex can freely choose materials without assembly and reduce joints, to solve the problem that some products can not be mass-produced because of special structure.

  1. The working principle of Overmolding

Color injection molding products need a male mold and two female molds, the first injection molding in the male mold and the first female mold, after molding open the mold, without demoulding, directly changed to the second female mold, second injection molding, demoulding can get two-color injection products. In actual production, usually two groups of male mold, each group is responsible for one injection, through the vertical direction of 180° to switch different female mold.

  1. The application of Overmolding

The overmolding process has now been widely used in automobiles, electronic products, power tools, medical products, household appliances, toys, and almost all plastic fields. Color injection molding can produce various color-matching products, such as toys, stationery, etc.

  1. What is the difference between double injection molding and overmolding?

Double injection molding is to make a colored plastic part on the first monochrome injection molding machine and then manually put it into the second mold for injection molding; no special injection molding machine is required. A two-color injection molding machine completes Overmolding; there are two injection molding, all completed in the two-color injection molding machine, usually using a special two-color injection molding machine.

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