What is two-color injection molding and the principles and process requirements?

- Feb 26, 2019-


What is two-color injection molding and the principles and process requirements?


First, what is two-color injection molding?


   The so-called two-color injection molding refers to a molding method in which two different color plastics are injected into the same mold. It can make plastic parts appear in two different colors, and can make the plastic parts have a regular pattern or irregular cloud-like color to improve the practicality and aesthetics of the plastic parts.


  Second, the principle of two-color injection


    It has two barrels, each of which is identical in construction and use to a common injection molded barrel. Each cylinder has its own passage communicating with the nozzle, and the opening and closing valves 2, 4 are also installed in the nozzle passage. During molding, after the melt is plasticized in the cylinder, the order of the melt entering the nozzle and the proportion of the discharged material are controlled by the opening and closing valves 2, 4, and then injected into the cavity by the nozzle. You can get a variety of plastic products with different color mixing effects.


  Double pattern injection molding principle


   It also has two barrels 1 and 5, the nozzle structure of which is somewhat special, in addition to the function of the usual nozzle, it can also be rotated by the gear 3 mounted at the rear. During molding, the different sizes of the melt are respectively plasticized in the cylinders 1, 5, and the gear 3 drives the rotary shaft 4 to rotate, so that the different colors of the melt alternately enter the cavity, thereby obtaining different colors in the form of radiation from the center to the periphery. Patterned plastic products.


  Third, two-color injection molding requirements


Material requirements


   Two-color injection molded mating materials must meet two basic compatibility conditions, namely, adhesive compatibility and process compatibility.


Process requirements:


Soft and hard plastic double shot design


  There must be a certain temperature difference between the two materials. It is generally recommended to be 60 ° C. It is recommended to be at least 30 ° C. The melting temperature of the first shot material is high. Generally, the first shot is PC or PC/abs, and the second shot is TPU or TPE. , PC thickness 0.6-0.7mm, software 0.4mm or more.


  Try to widen the contact area, make the groove to increase the adhesion, or use the core for the first shot, and the second part of the material is injected into the first shot. The surface of the first shot is as rough as possible.


Transparent and non-transparent bijective design


   The dual-lens design of the small lens: the first shot is non-transparent, the second shot is made of lens, the first shot uses the PC melting point as high as possible, and the second shot uses PMMA.


   Transparent and non-transparent two-shot design for decoration: the first shot is non-transparent material, the second shot is transparent material, the non-transparent material is commonly used for high temperature PC, and the second shot transparent material is PMMA or PC. The PC needs to be sprayed with UV to protect it. PMMA can be UV or reinforced. If there are characters on the surface, UV must be selected.



 Asia Billion as a professional plastic injection molding company, we are a expert for the two-color injection molding technics and over molding. if you have any project which need this type supplier , please contact us freely at :


Asia Billion Innovational Technology Limited

ADD:  Building 9 , Wantou Industrial Park, Hongxing Village,SongGang Town, Shenzhen City, China    518105 

E-mail: sales@ab-industry.com  
Phone: 0086-134 8063 8827
Website: www.ab-industry.com 


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