Multi K injection moulding - Rosti

Multi-K injection moulding

We can create your product using multiple materials, colours and transparencies in the same mould. With this technique, you get a single, homogeneous part from the mould, without the need for further assembly. The efficiency gains can be significant, and our industry experts can advise on whether multi-material moulding is the right option for you.

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Rosti - John Kidd
John Kidd

Regional Technical Director Asia

Rosti - Tony Austin
Tony Austin

European Technical Director

The many benefits of multi-material moulding

Rosti use multi-shot injection moulding to produce components of two or more different materials from a single tool. It is an effective and efficient method because it lets you assemble your products in-mould, without any additional production steps. For example, if you want to make plastic items with rubber grips, we could inject both substances into the same mould, and eliminate the need for gluing, bolting or screwing.

We also use this method for items made from a single material, but with multiple colours, shades or transparencies. This can be useful for making objects with viewing windows, or for making multi-coloured items without painting.

Sandwich injection moulding is another effective form of Multi-K moulding that we provide, that lets you use different materials for the outer skin and inner core of your product. This technique can be used to create more sustainable products, by using post consumer recycled (PCR) resin to form the core of your object before applying a skin that looks or feels more attractive. You can also use the outer skin as protection for a more delicate object on the inside, by using a layer of waterproof or UV-protective material.

In most cases, the materials are bonded at the molecular level so there is no possibility of the layers separating at a later stage. This makes it a useful technique for moulding seals and gaskets, and also in the healthcare and food industries since objects do not require adhesives that can breed contamination.

Rosti brings technology and knowledge

Because it eliminates so much assembly and processing, multi-material moulding can be an extremely efficient process. However, it demands intricate toolmaking, careful control of the temperatures of the materials and the mould, and precise monitoring of moving and/or rotating parts. With that in mind, the decision about whether to use this technique needs to be made early in the design stage – and it is worth consulting Rosti’s experts to help guide you through this process.

All of Rosti’s manufacturing sites have cutting-edge facilities capable of meeting the technical requirements of the most complex multi-material projects. More importantly, we have expertise and experience built up over 70 years that we use to identify the processes that best meet your needs, taking into account the total cost of ownership throughout the project, the time to market, and the likely volume of units to be produced.

Working with Rosti, you get honest, expert advice during the design stage to help you decide whether multi-k moulding is the best option for you. In fact, we can support you throughout the entire production process from design to delivery, and from concept to reality.

Multi-shot, multi-K of multi-material?

The language around these methods can be a little confusing, partly because different terms are often used to describe the same processes. Multi-material injection moulding and multi-K injection moulding mean the same thing – they describe the method of using a single mould or tool to create an item of more than one material, colour or transparency.

The K in ‘multi-K’ comes from the German word for …

… for component – komponente. So if you see a reference to 2K or 3K moulding, it means that two or three different materials are used in the moulding process.

Multi-shot is often used interchangeably …

… with multi-K and multi-material but it actually has a more specific meaning. It refers to moulding where material is injected in stages or shots. Multi-K or multi-material moulding are broader terms, and can refer to production methods where materials are injected either in stages or simultaneously.

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