This document discusses two-color injection molding processes and mold forms. It describes how two-color injection molding machines use two sets of injection devices that must have identical parameters. It also explains that higher melt temperatures, injection pressures, and mold temperatures are needed for two-color products compared to single-color products. Finally, it outlines the two main forms for two-color molds: convex die translation and convex die rotation.

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Two-color Injection Molding Products Processing And Forming
Written By Jasmine HL
This article is about Production process characteristics and mold form of two-color injection
molding products.
Production process characteristics of injection molding two-color products
1. The two-color injection molding machine consists of two sets of plasticizing injection devices
with the same structure and specifications. According to the production model, the nozzle should
have a special structure or be equipped with two sets of forming dies with the same structure
that can be rotated and transposed.
When plasticizing and injecting, process parameters such as melt temperature, injection pressure,
and melt volume in the two sets of plastic injection devices are required to be the same. It is
necessary to minimize the fluctuation of process parameters in the two sets of devices.
2. Compared with two-color injection-molded plastic products, the melt temperature and an
injection pressure of the two-color injection-molded plastic products must adopt higher
parameter values. The main reason is that the mold runner in the two-color injection molding is
relatively long, the structure is complicated, and the resistance to injection melt flow is large.
3． Two-color injection-molded plastic products should use raw materials with good thermal
stability and low melt viscosity to avoid decomposition due to high melt temperature and long
residence time in the flow channel. The most commonly used plastics are polyolefin resins,
polystyrene, and ABS materials.
4． When two-color plastic products are injection-molded, in order to make two different colors
of molten material weld well in the mold during molding to ensure the molding quality of
injection-molded products, higher melt temperature, and higher mold temperature should be
used. , Higher injection pressure and injection rate.
Two-color mold structure

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The traditional two-color injection mold has two forms of "convex die translation" and "convex
die rotation".
① The die of "convex die translation" has two concave dies and one convex die. When the first
barrel is shot, the convex mold is closed with the first concave mold. Complete the first plastic
injection. After the first plastic is solidified, the concave and convex molds are separated, and the
semi-finished product formed by the first plastic stays in the convex mold and moves with the
convex mold to the position aligned with the second concave mold. After the injection molding
machine is closed, a second barrel is injected with a second plastic. After the second plastic has
solidified, the injection molding machine opens the mold and takes out the complete product.
② The two-color die in the form of a "rotating die" has two concave dies and two convex dies
combined back-to-back. This convex die can be rotated. The two-side injection molding machine
equipped with two barrels, the second barrel is preferably designed in the vertical direction of
the injection molding machine movement direction. Two different plastics can be injected at the
same time. When the two plastics injected are solidified, the injection molding machine opens
and ejects the complete product automatically. After the product is taken out, the "rotatable
punch" is turned through 180 degrees. The injection molding machine is closed and the next
cycle is performed.
Because the first and second barrels of the "die transfer" mode is injected in turn, the first and
second barrels of the "die rotation" mode are injected simultaneously. Therefore, for the same
product, the production efficiency of the "embossed die rotation" mode is twice as high as that
of the "embossed die translation" mode.