Sometimes known as double Injection,  2 material, 2 shot molding or 2K molding, is an innovative manufacturing process used to produce complicated molded parts from two different materials. Through a highly specialized and automated process we carefully control the injection of multiple materials, including two different kinds of resin, into a single, multi-chambered mold.

What is 2k shot plastic injection molding

 2k shot Injection in performed on one machine that is programmed to perform two injections in one cycle. In the first cycle, a nozzle injects plastic into a mold. The mold is then automatically rotated and a different type of plastic is injected into the mold from a second nozzle. and are molded in two times, but the product only molds once. this is called 2k injection molding, this process need special 2k plastic injection machine. current, it is not secret technical, on the market, there also have many branded 2color injection machine manufacturer, such as HaiTian, LiKin, also Arburg and so on.

Double Injection Molding optimizes co-polymerization of hard and soft materials to create powerful molecular bond. The result is a single part with production and feature advantages. It can be used for a variety of product designs across all industries. It also allows for molding using clear plastics, colored graphics and stylish finishes which improves your product functionality and marketplace value.

2k shot injection molding with Hot Runner

2k molding Vs overmolding

2k Molding
in other words, one product is moulded from two different plastics. Common two-color products, such as the toothbrush used for brushing our teeth in the morning, are produced from 2k injection molds. The handle of the toothbrush is hard plastic but a part of the soft rubber is also embedded on it. Adding a part of the soft rubber is mainly a better feel,  more beautiful and look more upscale.At present, the 2k injection mold can be made into one set of molds or two sets of molds, but both one set and two sets molds are simultaneously installed on one injection molding machine.
overmolding
the plastic mold is to put a product that has already been produced into the mold and then inject another plastic. The effect of the overmolding and the 2k molding is the same, but the overmolding is At the time of production, the first produced product should be put into the mold and re-injected, and completed in two parts, and the 2k molding is produced in the same set of molds.
    Therefore, the difference between 2k shot injection mold and overmolding is that the 2k injection mold are produced in one injection molding machine. However, the overmolding is divided into two injections, which cannot be produced at one time, and it needs to be injected twice.

The benefits of 2k injection moulding

with 2k injection moulding, we can inject different hardness material or different color material into one part, it also with precise separate line.
this can bring parts with much better appearance and better hand feeling.

The disadvantages of 2K molding

since the 2k molding is more precise compare to single injection molding. the mold and mold component have to be more precision when it been built. caused the price of 2k molding is more expensive than single injection molding. however the cost can be covered because assemble steps and hand labour can be eliminated.

2k injection molding plastic material

2k shot injection plastic material

2k shot molding plastic material bonding

2k shot plastic material bonding
  1. the accuracy of the moldbase is high, generally using Futuba moldbase.
  1. The guide pin and bush of the moldbase must be symmetrical about the top, bottom, left and right, and the mold cavity and core side must be symmetrical.
  2. The mold core side should be rotated 180 degrees, and the mold cavity side does not move.
  3. The spacing of the products must be based on the spacing of the nozzles of the injection molding machine. The spacing of the nozzles of the 2k injection molding machines abroad is adjustable, and some are not adjustable, and the domestic ones are not adjustable.
  4. Two independent ejector systems, the ejector bar is also two. The two products of the cavity side are the same, the ejector pin are the same, and the rotation relationship is not made into a parallel relationship.
  5.  The ejector plate can only be reset by spring. It is not possible to force the reset by the screw because the mold core side should be rotated.
  6. The side lock must be on the four sides of the center of the mold, and the cavity and core of molds are symmetrical. Otherwise, when the core side of mold is rotated 180, it will not be aligned with the cavity side of mold.
  7. Pay attention to the direction of the parallel nozzle of the injection molding machine provided by the customer, which is the X-axis or the Y-axis, so as to determine the layout of the product ranking.
  8. The direction of cooling water inlet  and out must be on the side of the top and bottom side, and the inlet and out of each circulating water must be on the same side. The cooling water should not be inlet in the topside, and and outlet on bottom side. Because the mold core side should be rotated 180 degrees, pay attention to the size of the mold. Do not exceed the height of the water tank of the injection molding machine, otherwise the cooling water cannot be transported.
  9. The first injection of the product should be placed on the non-operating side, because the first injection of the product should be rotated 180 degrees for the second injection, just to the operating side, easy to take the product out.
  10. The Clamping slot for the export mold should be on the operating side and the non-operating side, not on the top and bottom side, because their products should be fully automatic running.

2K shot injection molding Youtube Video

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