关于 2 次注射塑料注射，您需要了解什么？

1、整个过程分为两个阶段。

2、有几个问题需要考虑。

3、旋转成型和活动芯是工艺中的两种变体。

4、有一定条件要特别注意，才能保证顺利运行

5、2次注射可以为产品和成型公司的运营带来好处。

2 次注射塑料注射工艺可以称为其他几个名称，例如双次注射、多次注射或包覆成型。

关于二次注塑成型工艺存在很多误解。成型公司通常会忽视 2 次注射工艺的优势，因为他们认为这是一种复杂的方法、非常昂贵且耗时。

尽管对此过程有先入之见，但它作为一种塑料注射成型方法也有其优势。

如果您想了解此过程，请继续阅读。

这些是成型公司应该了解的关于二次注塑工艺的事情。

What is the process involved with 2-shot plastic injection method?

In general, this process molds together two varying plastic resins in one distinct machining cycle.

A 2-shot plastic injection molding method has two main phases.

First phase – this phase has a likeness to the traditional way of injection molding where a resin is injected inside a mold. From that point on, the mold is cooled to form a solid structure.

Second phase – The solidified part is then moved to a second mold. The transfer is either done through a robotic arm or a rotating platen. From that point, a second resin shot is injected through a certain part of the solidified structure. The point of injection varies depending on the design of the structure. A molecular bond is formed by the two plastic resins. Finally, the parts are first cooled before it is ejected from the mold.

What concerns could you encounter with the process?

The method itself is not overly complicated as it is often perceived by people who are considering starting up their own molding company.

Although, the execution of the process is notably challenging to master. With the nature of the industry, which is producing immense amounts of products, even small errors can equate to a higher cost. That is why, for a 2-shot plastic injection process, workers must have expert-level technical skills and impeccable eye for detail.

What are the 2-shot molding variations?

Even with the initial steps in a 2-shot molding process, there are also several modified methods that can be applied.

A rotary and a movable core ate the two variations of a 2-shot injection molding process. These two processes both utilize a second injection unit and requires two processes and two runner systems.

Rotary – This process utilizes a tool called a rotary plate which can either be built in already or activated either by a rack system or by hydraulics.

In general, this method utilizes a vertical platen, which is positioned on one side of the clamp. This vertical platen will then rotate on a horizontal axis.

A second runner system and two sets of ejector plates must be kept running, and the movable parts must be rotating. The movable half is called “ejector cavities,” while the unmoving half is referred to as the “cover cavities.”

To produce a part per cycle, two pairs of identical ejector cavities and two sets of cover cavities must be used. One of the cover cavities is specifically intended for the first-shot, while the other is for the second one.

Locators are essential parts of the mold because it ensured that pieces are accurately centered in the rotary platen. Concerns regarding alignment may arise if the mold is not centered.

A wrong alignment may cause damage on the machine’s shutoffs, bushings, or leather pins, especially when the mold takes a 180° rotation.

After injecting the shots inside the cavities, the molds are rotated. By doing so, the first shot will align with the second-shot cavity.

For every cycle, the first-shot is molded along with the basic material. At the same time, the second-shot is molded with the parts of the first-shot that was used from the previous cycle.

Things you need to pay attention during the cycles, especially when the first shot is in the position of the second-shot, are crush and support.

Crush – This is the shutoff that protects the first shot material and prevents the second-shot material from oozing onto the first-shot.

This raised steel cavity is pressed into the first-shot in order to prevent leakage.

For thicker wall stock, supplementary crush is added to make up for the extra shrinkage. More crush can be achieved by adding steel to the shutoff of the second-shot.

Support – This is applied on the first-shot part to ensure that the pressure from the second-shot cavity does not deform the first-shot part.

Movable core – Unlike the earlier method, a movable core process does not require a rotary platen and utilizes a normal mold. This mold utilizes only one part and one cavity.

In order to regulate for the second-shot, the movable core maneuver internally.

After the mold close and the first-shot is injected, it then slides and the second-shot is set and injected. These steps form one full cycle.

What are the guidelines for tool design?

Here are some tips for a hassle-free operation.

The first shot cavity must be supported concerning the pressure of the second-shot cavity.

In order to prevent malformation, undercuts may sometimes be necessary to secure the first shot.

The hydraulic cylinder that activates the cores must be powerful enough against the pressure of cavity plastics. Doing so will ensure that there won’t be any flash in the finish products.

What are the benefits of a 2-shot molding process?

Unlike how most people view a 2-shot molding process, this process has advantages the people may have overlooked.

Efficient and cost-effective

More than one finished product can be finished in just one processing since a number of mold pieces can be processed simultaneously.

Secondary operations and handling like over molding, insert molding, and further validation are no longer required.

High-quality products

The multiple shots form a strong bond among the materials and results to higher quality goods.

Better intricacy in design

By utilizing various materials, even complex and intricate designs can be easily accomplished.

Multi-colored parts are better produced using a 2-shot/multiple-shot molding process since it is possible to utilize several materials at just one run.