Two Shot Injection Molding

Benefits and Differences of Two Shot Injection Molding

There are a variety of manufacturing methods used to create products using plastic polymers, including two shot injection molding, compression thermoset molding and extrusion. While all of these are viable manufacturing processes, there are several advantages to this process that make it the top choice for many plastics manufacturers. The process is relatively simple; one material is injected into a mold in order to make the initial section of the product, followed by a second injection of a secondary material that is compatible with the original material. There are three good reasons many manufacturers use this method of manufacturing plastics or polymers.

Two Shot Injection Molding Is Cost Effective

The two-step process needs only one machine cycle, rotating the initial mold out of the way and putting the secondary mold around the product so that the second, compatible thermoplastic can be inserted into the second mold. Because the technique uses only one cycle instead of separate machine cycles, it costs less for any production run and requires fewer employees to make the finished product while delivering more items per run. It also ensures a strong bond between the materials without the need for further assembly down the line.

Enhanced Product Quality

Two shot injection molding enhances the quality of most thermoplastic items in several ways:

  • Improved esthetics. Items look better and are more appealing to the consumer when they are crafted of different colored plastics or polymers. The merchandise looks more expensive if it utilizes more than one color or texture
  • Improved ergonomics. Because the process allows for the use of soft touch surfaces, the resulting items can have ergonomically designed handles or other parts. This is particularly important for tools, medical devices and other hand-held items.
  • It provides for a better seal when silicone plastics and other rubbery materials are used for gaskets and other parts that require a strong seal.
  • It lets you combine both hard and soft polymers for outstanding comfort and utility for even the smallest of products.
  • It can greatly reduce the number of misalignments when compared to over-molding or more traditional insert processes.
  • It enables manufacturers to create more complex mold designs using multiple materials that can’t be effectively bonded using other processes.
  • The bond created is exceptionally strong, creating a product that is more durable, more reliable and with a longer life.


Product manufacturers favor two shot injection molding for a wide range of applications, including automotive interior parts, medical devices, tools and toys. It allows manufacturers to combine a variety of materials and colors to create a final product that is both strong and attractive. Some materials that can be effectively combined with this process include silicone and thermoplastics, nylon and thermoplastic elastomers or hard nylon and soft touch materials.

Two shot injection molding could be the answer to your company’s product production dilemma. An experienced plastics manufacturer can guide you through the process from concept to finished merchandise and ensure a cost effective solution.

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