• 2023-11-06
• 573
• 5 Comments

The difference between the two-color mold and the coated mold

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 method, the nozzle should have a special structure, or be equipped with two component molds with the same structure that can be rotated and transposed. When plasticizing injection, the process parameters such as melt temperature, injection pressure and injection melt amount in the two plasticizing injection devices are required to be the same, and the fluctuation difference of process parameters in the two devices should be minimized.

2. Compared with ordinary injection molding plastic products, the melting temperature and injection pressure of two-color injection molding plastic products should adopt higher parameter values. The main reason is that the mold flow channel in the two-color injection molding is relatively long, the structure is relatively complex, and the flow resistance of the injection molten material is larger.

3. Two-color injection molding plastic products should choose 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 widely used plastics are polyolefin resins, polystyrene and ABS materials.

4. In the injection molding of two-color plastic products, in order to make two different colors of molten materials in the molding can be well fused in the mold, to ensure the molding quality of injection products, higher melting temperature, higher mold temperature, higher injection pressure and injection rate should be used.

Two-color mold structure form

The traditional two-color injection mold has two forms: "punch translation" and "punch rotation".

① The "punch translation" die has two concave dies and one punch. When the first barrel is shot, the punch is closed with the first die. Complete the injection of the first plastic. After the first kind of plastic solidifies, the concave and punch are separated, and the semi-finished product formed by the first kind of plastic stays in the punch and moves with the punch to the position aligned with the second punch. After the injection molding machine is closed, the second cylinder is injected with the second plastic. After the second kind of plastic solidifies, the injection molding machine opens the mold and takes out the complete product.

② The two-color mold in the form of "punch rotation" has two concave dies and a punch composed of two back-to-back combinations, which can be rotated. The two sides of the injection molding machine are equipped with two cylinders, and the second cylinder is designed in the vertical direction of the movement direction of the injection molding machine. Two different plastics can be injected at the same time. When the two types of injected plastic solidify, the injection molding machine opens and automatically ejects the complete product. After removing the product, the "rotatable punch" is turned 180 degrees. The injection molding machine closes and proceeds to the next cycle.

Because the first and second cylinders of the "punch translation" mode are injected in turn, and the first and second cylinders of the "punch rotation" mode are injected at the same time. Therefore, the same product, the efficiency of production with the "punch rotation" mode is twice that of production with the "punch translation" mode.


Coated mold and two-color mold difference

1.Two-color mold: two kinds of plastic materials in the same injection molding machine injection molding, divided into two molding, but the product only out of the mold once. Generally, this molding process is also called double injection molding, which is usually completed by a set of molds and requires a special two-color injection molding machine. Two-color mold can be two different characteristics of resin and color, into a single two-color product, can reduce the formation of the molded product and post-processing engineering. Save the cost of melting and printing, increase the aesthetic visual effect of the product, improve the grade and added value of the product. It not only has the function of anti-slip and increase friction, but also the flexible resin material makes it more ergonomic and feels better. Two-color injection molding products have high quality stability, easy control of product deformation, short molding cycle, high output, 7% lower loss than plastic injection molding, and 20%-30% lower manufacturing cost than plastic injection.

2. Encapsulation mold (secondary molding) : two kinds of plastic materials are not necessarily in the same injection molding machine, divided into two molding; After the product is removed from a set of molds, it is put into another set of molds for a second injection molding. Therefore, in general, this molding process is usually completed by 2 sets of molds, without the need for a special two-color injection molding machine, and the mold structure is the same as that of the single-color injection mold, mainly by adjusting the flow rate of the injection parameters to control the combination point of the seed material. The adhesive die is mainly soft adhesive and hard adhesive, of which the soft adhesive is commonly used in artificial rubber, TPU, TPR and other adhesive materials, and the hard adhesive can be ABS, PC, PP and so on.