Laszeray Technology

What Is Multi-Shot Plastic Injection Molding?

Multi-shot plastic injection molding is the process of injecting two or more plastic materials or colors into a single mold simultaneously to create a single part or component. The process can also be used with various materials besides plastics, such as using various metals with plastics.

In conventional (single) injection molding, a single material is injected into the mold. The material is almost always liquid or just beyond its melting point so that it flows easily into the mold and fills in all areas. After it is injected, the material is cooled and starts to solidify.

Then the mold is opened and the finished part or component is removed. Next, any secondary and finishing processes are completed like etching, debridement, assembly, and so on.

With multi-shot injection molding, the processes are similar. However, instead of working with a single material, the injection molding machine has multiple injectors each filled with the necessary material. The number of injectors on multi-shot molding machines can vary with two being the fewest and up to six the maximum.

How Does Multi-Shot Plastic Injection Molding Work?

First, the mold must be created that will be used to produce the part or component. With a multi-shot machine, there will be several different molds, depending on the number of injectors being used. At each step in the process, more material is added until after the final injection of material.

For example, in a 3-stage multi-shot injection molding, the machine would be configured for three injectors. Each injector is connected to the appropriate material. The mold used to make the part or component would have three different cuts.

The first mold cut happens when the first material is injected after the mold is closed. Once it cools, then the machine automatically moves the material into the second mold. The mold is closed. Now materials are injected into the first and second mold.

In the second mold, more material is added to the material made in the first mold. Once these cool, again the mold opens and the machine moves the materials from the second mold to the third mold and the first mold to the second mold.

In the next step, the third material is injected into the third mold to finalize the part or component. Materials are injected into the first and second molds again as well. Last, once cooled, the mold opens and the machine automatically shifts each material into the next mold while ejecting the finished piece.

Keep in mind, this is just a general overview of the process and can vary based on the type of plastic injection molding machine being used.

What Are Some Benefits of Multi-Shot Injection Molding?


There are several benefits of using multi-shot injection molding when appropriate, including:

  • Lower Production Costs: Instead of having to use multiple machines, a single machine can produce the desired part or component.
  • Eliminates Most Secondary Processes: You can add graphics, logos, or text during one of the steps in the molding process.
  • Reduced Production Cycle Times: The time required to produce finished parts and components is less. Production can also be automated for faster output.
  • Improved Productivity: Your output levels will be much higher since production cycle times are reduced.
  • Improved Quality: Since the part or component is being produced in a single machine, the quality is improved.
  • Reduction in Assembly Operations: You don’t have to put together two, three, or more parts and components since it is possible to mold the entire finished part or component in a multi-shot machine.

To learn more about our multi-shot plastic injection molding service and how it could benefit your workpieces and production processes, please feel free to contact Laszeray Technology, LLC at 440-582-8430 today! We offer customizable plastic injection molding, rapid prototyping, product design, and more.

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