What is two-shot injection moulding?

Two-shot moulding, also known as multi-shot, double-shot, and dual-shot moulding, is an injection moulding procedure where two different plastic resins are moulded together within a single machining cycle. These substances are administered sequentially rather than simultaneously, and the product is not discharged from the mould in between the two shoots, but it is produced in a single step.

What is the two-shot injection moulding process?

Since the procedure is completed in a single step, just one mould tool is needed for two-shot moulding.

The first shape of the product is created when the first polymer (the substrate) is injected into the chamber of the first-shot tool. After rotating 180 degrees and separating while still holding the first shot, the mould tool closes with the first shot aligned with the second cavity of the tool. Over the substrate, the second polymer is injected into the second-shot cavity. The finished moulding is then pushed off the mould tool once the tool has been turned 180 degrees back to where it started.

2 shot injection moulding process

What are two-shot injection moulding applications?

For complex, multi-colored, and multi-material plastic goods, especially in high-volume manufacturing circumstances, two-shot injection moulding is the best plastic moulding technique. Two-shot moulded parts are utilised in almost every industry, from consumer products to construction, such as toys, automobile components, medical equipment, containers, and toiletries. Two-shot moulding is common in the production of:

  • Toys
  • Containers
  • Toiletries
  • Gardening tools
  • Movable  parts
  • Surgery and medical equipment
  • Kitchen utensils
  • Other multi-colour, multi-material parts

What are the benefits of two-shot injection moulding?

As two-shot injection moulding does not require several production phases, it offers moulding manufacturers a number of benefits, including reduced manufacturing costs, improved ergonomics and aesthetics, superior mechanical bonding, quicker production times and more efficient material usage. Engineers can readily produce multi-material and multi-colored items as a consequence, without the need for additional machining stages.

Reduced manufacturing costs:

As the number of parts in a final assembly is decreased with two-shot injection moulding, there could be a huge saving in research and development, engineering, and validation expenses for each increased part number.

Improved aesthetics and ergonomics:

Products created using a two-shot method can maintain the necessary structural characteristics while being aesthetic and ergonomic appealing. The load-bearing structural component can be moulded in the first phase of this procedure, and the finishing touches can be applied in the second step using a more attractive material. It is also simple to cover or add to structural plastic with materials that are more suitable for human contact as it offers a greater grip and a gentler touch, soft, rubbery material is more suited for human hands.

Superior mechanical bonding:

Given excellent material selection, the product’s various levels join together molecularly throughout the moulding process, hence, the bond is frequently more durable than traditional moulding and assembly and even more durable than other cutting-edge techniques like over- and insert moulding.

Quicker production time:

As there is frequently no need to do secondary assembly of the item since many tiers of a product can be added during this operation, injection moulders could significantly reduce production time. While the time of one cycle could be longer compared to the traditional injection moulding process, it is still faster than running 2 separate cycles to make the same item. 

More efficient material usage:

Two-shot moulding could help combine the greatest qualities of different materials, to create complex mould patterns with strong bonding to ensure durability and longevity.


Micro Systems is a UK based manufacturer of medical moulds, micro moulds and medical injection-moulded parts. We cater for our customers starting from mould design through mould manufacturing and development to validation within an ISO Class 7 cleanroom. We are ISO 13485 and ISO 9001 certified. Micro Systems products include moulds for medical or high-precision plastic manufacturers and injection-moulded medical parts produced on-site at our Optimold facility. Contact us today to get the best quote for your medical injection moulding project. 

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(Photo: Micro Systems)