Multi-Shot Or Double-Shot Injection Moulding

Multi-shot or Double-Shot Injection Molding

Our Experience in  Double-shot Moulding

Why Choose Kore?

  • We advocate multi-shot moulding for its benefits - one of which is actually green manufacturing.
  • Moreover, one of our core competencies is 2K, and 3K moulding technologies, and
  • we have been doing this for over a decade!

Want to know more? Do talk to us today about how 2K or 3K technologies could help you with your products.

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What is Multi-shot Injection Moulding?

Multi-shot moulding is a process that moulds two or more more materials onto each other, in a single injection moulding cycle.

Unsurprisingly, the most common type of multi-shot moulding is the double-shot injection moulding, or what is commonly known as 2K injection moulding.

That is because 3K and more material or colour injection processes entail more detailed studies on the bonding of materials, geometry parts, and many other considerations.

At Kore, we are experienced in 3K injection moulding. You can read about it here.

Since double-shot injection moulding is the most common multi-shot injection type, we will discuss this topic in further details below.

So, What is Double-Shot Injection Moulding?

Double-shot plastic injection moulding is the process that moulds two materials onto each other, in a single injection moulding cycle.

Other common terms for double-shot injection moulding are:

  • Twin-Shot Injection Moulding
  • 2K Injection Moulding
  • 2-Shot or Two-Shot Injection Moulding
  • Double-Colour Injection Moulding
  • Multi-Colour Injection Moulding
  • Transfer Moulding

How it is done

First, the substrate is injected into its respective mould cavity, while the second shot over mould is injected into its own cavity over the substrate from the first half of the injection moulding cycle.

Next, the mould opens and the moving half or the core side of the mould is rotated 180 degrees and closed for the second half of the injection moulding cycle.

Finally, the finished two-shot part is finally ejected from the mould for manual or robot pick.

Multi-Material Bonding

For a double-shot plastic injection moulding to work, the substrate and over-mould plastic material has to be chemically compatible in order  for them to form a solid bond.

Alternatively, in cases where the substrate and over-mould plastic material are not chemically compatible, the substrate geometry has to incorporate mechanical bonding features such as through holes or other similar features.

These features allow the over-molded plastic material to mechanically “grab” onto the chemically incompatible substrate.

Read more about our past case studies of different types of multi-shot moulds here

Benefits of Multi-Shot Injection Molding

  • Multi-shot moulding method can significantly improves the appearance and appeal of the product
  • As such technology is a single moulding process that joins two parts, it significantly reduces the process costs by eliminating manual assembly or the use of adhesive.
  • Moreover, 2K injection moulding also provides a stronger and more durable product; as opposed to an assembled product with two individual moulded components
  • Also, an added benefit is its ability to provide beautiful multi-colored product. This eliminates the need for secondary process such as painting or plating.
  • On top of that, two-shot moulding produces complex parts that are capable of extra functions.
  • Interestingly, such products are much more functionally robust widely used in dust, shock, and waterproofing applications; e.g. IP68 housings

It is important to note that such method is ideal for surfaces with maximum friction, i.e. first shot hard plastics with a second shot soft rubber designed to enhance grip non-slip surfaces for industrial hand-held devices and infant products.

In What Areas is Double-shot Moulding Best Applied?

The two shot injection mould are ideal for:

  • buttons and switches, handles, grips and caps.
  • multi-colored products or painted logos.
  • parts that function as noise pads and vibration damper.
  • aerospace, automotive, medical and consumer industries
  • and many more

In conclusion, this process is truly widely used and trusted for its versatility and durability.

Case Studies

Read about our multi-shot moulding case studies here

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