Multi K injection moulding - Rosti

Multi-k Injection Moulding

Multi-k or multi-material moulding is a powerful technique. It offers cost savings and significant efficiency gains and can transform the way you produce your goods. At Rosti, we 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. 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
E-mail: rosti@rosti.com

Rosti - Tony Austin
Tony Austin

European Technical Director
E-mail: sales@rosti.com

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.

The opportunities are practically endless, with skill and imagination.

What is multi-k moulding?

Multi-k or multi-material moulding is known by many names. It is also referred to as overinjection and includes the multi-shot injection process under its umbrella. It is one of the most widespread and beneficial techniques used in plastic injection moulding today. It creates a single part out of two materials or more, in the same mould and the same process. As you would expect, this presents significant advantages for production, personalization, and efficiency.

Different methods of multi-material moulding

Multi-material injection moulding comprises varying techniques, which all feature the same core functionality and utility. Your choice of multi-k injection moulding technique depends on your project and product requirements. At Rosti we work closely with you to develop an efficient and effective plan of action, using the most appropriate techniques for the materials and goods. 

Sandwich injection moulding is one 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 applied 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 employing 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 for applications in the healthcare and food industries, since objects do not require adhesives that can breed contamination.

Rosti brings technology and knowledge to your projects

The advantages of the multi-material injection moulding process are clear – and the most visible is surely cost savings. Without using the process, the two or more components in a product must be designed and built separately, and then assembled in the post-production stage. This obviously entails extra costs, which the multi-k system removes.  

For example, if you were manufacturing a hairbrush with a plastic head and a rubber handle, you would require two moulds and there would be two production runs to produce the components from these moulds. This would increase production time and cost. Plus, the post-production system requirements would need to be added on. And there would be an increased cost associated with storing the components after manufacture and prior to completion. 

Multi-K moulding streamlines the process by removing the post-production stage. 

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.

Discover multi-k injection moulding with Rosti

All of Rosti’s manufacturing sites have cutting-edge facilities capable of meeting the technical requirements of the most complex multi-material projects. We know your needs and we understand how to apply techniques to meet them. 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.

Contact us today to start your multi-material moulding journey.


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

You would be forgiven for feeling slightly baffled when reading about these techniques for the first time. 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.

If you have any questions about the processes and the different terminology, feel free to ask us.

You would be forgiven for feeling slightly baffled when reading about these techniques for the first time. 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.

If you have any questions about the processes and the different terminology, feel free to ask us.

If you have any questions about the processes and the different terminology, feel free to ask us.

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

… component – “komponente”. So, if you see a reference to 2K or 3K moulding, it simply means that two or three different materials, or components, are used in the moulding process. Materials commonly used include thermoplastics and thermosets, plus liquid silicone rubber.

Multi-shot is often used interchangeably …

… with multi-K and multi-material but it actually has a more specific meaning. (And to make things even more complicated, multi-shot injection moulding is also called twin-shot injection moulding in many cases.) Multi-shot injection moulding refers to moulding where material is injected in stages or shots. Multi-K or multi-material moulding are broader terms than multi-shot and can refer to production methods where materials are injected either in stages or simultaneously.

Work with the experts in multi-k injection moulding. Rosti empowers you to develop the best products for your market – all in a cost-effective, efficient manner. Contact us today to find out more about Rosti’s capabilities in injection moulding.

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