Jade Molds

Two Shot Injection Mold Making Solutions
A Great Option For:

  • Part consolidation and two colored parts
  • Parts with two different plastics or textures
  • Increasing injection molding efficiencies
  • Improving part quality when using two materials
  • Complex part designs

Two Shot Injection Molding

Two shot plastic injection molding is not as complex or as expensive or as time confusing as it may sound. But if you work with injection molding suppliers that do not have the experience to design, make, trial, QC, and launch two shot injection molds then you for sure will have problems.

When done well two shot injection moulding offers big manufacturing efficiencies, savings, and opens up your part to improved functionalities.

Tolerances and timelines are always important with injection mold making in general but particularly are important when designing a two shot injection mold. You need to make sure that the mold design actually delivers you the cost benefits, part dimension tolerances, part finish, and the mold safety that your project needs to be a successful high production two shot mold.

How does Two Shot Injection Molding work?

First off let’s talk terminology. You may have also heard two shot injection molding referred to as multi-shot, or dual shot, or double shot, or 2K molding, or overmolding. These terms generally apply to two shot injection molding except for overmolding which is a different process that can achieve the same results.

Specifically, with two shot injection molding there are two phases in the injection molding process. Phase one is just like traditional injection molding, a shot of resin forms a part and is cooled, but the part is not ejected from the tool. Phase two starts with repositioning that part, usually by rotating the mold in the press or a robotic arm. Then the second shot (of a different material) is applied to the first part and the two plastics form a molecular bond. The then two shot part is cooled and ejected and the process repeats.

A relatively simple sounding process that requires a lot of expert injection mold making engineering and a massive amount of injection mold making technical experience to be able to build a quality two shot injection mould that can perform high volume part production at a consistent and reliable level.

Applications For Two-Shot Injection Molding?

If you have a multi-colored part, or a complex part, or a part made from two different plastic materials, then two shot injection molding could be a good choice for your project. It is a great option for high volume part production and is widely used in industries like automotive, consumer products, medical devices, and agriculture to name a few.

A great option when you have a product that requires both hard and soft surface finishes. Or when you have a part that requires different texture in the same part. Also a good option for parts that are needed for acoustic or vibration reduction.

What Benefits Does Two-Shot Injection Molding Offer?

A great ROI. A very cost-efficient way to produce parts that would other wise require two seperate injection molds. Plus better bonding eliminates the need of an assembly of two different parts into one.

Consolidating Your Parts: when two parts become one at the injection molding level, assembly costs go down, engineering costs go down, and mold making costs go down.

Efficient Manufacturing: Two shot injection molds do the assembly work for you. Less labor means costs go down.

Better Quality: A single tool allows for tighter tolerances because you do not have to match up two different tools tolerances to make your multi component part work. Less scrap. Higher part accuracy.

Complex Part Designs: You can really get creative in your part design when you  know that you have a two shot injection molding process that can merge two different materials and colors together in a single process.

How does two shot injection molding compare to overmolding?

A KEY difference is that two shot injection molding creates a part made from two different materials using a rapid succession injection molding process, that is often fully automated. Whereas overmolding is a more labor intensive process with two distinct injection molding steps required to achieve the same result. At times with two completely different molds.

Two shot injection molding with it’s more advanced automated features matches well with higher part production projects. But it should be noted that these two shot molds cannot be run on all standard injection molding presses.

Overmolding is a better choice when you are looking at lower part production numbers and when you don’t have the specialized injection molding presses required to execute two shot injection molding.

Engineering Support is Key

Two shot injection molding is a relatively simple concept but you really need to know what you are doing as an engineer and injection mold maker to design, make, trial, and QC  a robust two shot injection mold that is suitable for high part production. 

Outside of the technical experience and expertise needed to make these two shot molds there are other unique considerations engineers must advise on. Not all plastics are compatible. Your engineer needs to choose two plastics that are chemically or thermally compatible with each other or your parts will fail. Alternatively there are also bonding agents that can be tried when using two plastics that are not completely compatible with each other, but this is generally not recommended if it can be avoided.

At Jade Molds we have been making custom injection molds in China for USA customers since 2006. Our engineers are based in the USA, India, and China, with our most experienced injection mold engineer in the USA with 40+ years experience. Not just USA based engineering but also a USA high tech approach to project management and quality control with a custom build project management system (with AI assist) and a custom build QC App. All the elements needed to pull off high production two shot injection molds that will run well and at pace in your facility in America. [email protected] to connect.

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