Cutting edge of composite processing

A UK company has recently doubled its capacity for precision cutting of composites – a process which it says is vital to reducing waste and improving efficiency.

Bindatex, headquartered in the North West of England is an ISO 9001 certified company which specialises in the precision cutting of difficult to cut materials – namely a range of fiber-reinforced thermosets and thermoplastics. The company’s cutting capabilities include slitting, traverse wound spooling, narrow width precision slitting for automated fiber placement (AFP) and automated tape laying (ATL), micrometer slitting/kiss cutting, sheet and die cutting, and flake/chopped fiber production. Currently, it is the only company in the UK that can undertake precision slitting of composite materials to widths as low as 1 mm.

They have the ability to process carbon and glass fiber prepreg materials in a range of formats including unidirectional (UD) tapes and traverse wound spools, thermoplastic and thermoset carbon fiber prepreg, woven fabrics and multi-axial fabrics and non-woven materials. (Figures 1., 2., 3.)

Bindatex can also produce ‘lay-ready’ splices in thermoplastic UD tapes manufactured with polyetheretherketone (PEEK), polyaryletherketone (PAEK) and polyetherketoneketone (PEKK) polymers. Also, they are able to deliver defined spool lengths which can help increase AFP and ATL equipment productivity.

The company recently doubled its capacity by investing in a new slitting line, increasing its narrow width composites slitting capacity to 30 tonnes per year. The new line can reportedly cut uni-directional (UD), prepreg and composite materials to widths as narrow as of 3.175 mm. This follows a move to new, bigger premises in 2018.

The company has invested in machines with industry 4.0 capability, allowing exact widths of spooling to be digitally captured. ‘We monitor slit width precisely and by extracting this valuable data while the machines are processing the material means we can work within our customers specification,’ said Chris Lever, Bindatex MD. (Figure 4.)

The company’s latest machines include an inline measuring system which measures slit width to ensure accuracy as the composite materials are being cut, and a camera inspection system for quality assurance (QA).

Cutting fabrics

In June 2019, Bindatex reported 10 years of partnership with a global composites manufacturer that required slitting of its multiaxial fabrics for applications in aerospace, marine and automotive industries

According to Bindatex, the use of multiaxial reinforcements in composite manufacturing is growing and this has been driven by the ability to slit these fabrics into a variety of tape widths. One of the advantages of using multiaxial composites over woven materials is that they can increase the efficiency of the lamination process, as multiple layers of thicker fabrics can be laid up more quickly. However, the construction of this type of material can present many more challenges during the slitting process, as it is important to ensure a clean cut and accurate slit edge without compromising the fiber orientation and the handling characteristics of the materials. Using the company’s cutting machines, tapes can be slit as narrow as 35 mm and multiple widths can be achieved from each roll. The advantage of mixing the slitting pattern within a single roll helps to reduce waste by maximising utilization from the material, Bindatex said.

The slit multiaxial tapes are used throughout the aerospace, marine and automotive industries, and applications range from the manufacture of high-performance components to carbon fiber wheels.

End users such as the National Composites Centre (NCC) based in Bristol have utilised Bindatex’s flexibility of cutting small volumes of slit tapes for research and development. Up until recently this consisted of a small number of orders a year, but demand from the global leader in composite technology has steadily increased in recent months, the company said.

 ‘We have been working a lot more closely with the NCC over the past year after they realised the extent of our capabilities. They were aware of our ability to slit and spool precision composites tapes, but they now see that we do a lot more than just that.’ said Chris. ‘We are experts at taking development, non-standard and often challenging to cut material and precision slit these to extremely high tolerances. Not only that, our lead times are relatively short compared to typical industry standards. One of our strengths, which I think customers such as the NCC appreciate, is that we understand the increasing need to work with smaller volumes. This flexibility allows them to work on different projects. We recognise the need to turn jobs around quickly.'

Bindatex’s latest news is that it has now cut 300 kg of prepreg and started work on their 14th order in two years for a large OEM supplying thermosets and thermoplastics. 

This order involves slitting thermoset prepreg composite down to 3.175 mm for an AFP application. The narrow width poses a challenge for composite cutting, according to the company.

I spoke to Chris Lever to find out more about the company and cutting process.

What’s the history of Bindatex?

I established the company in 2004. At the time, our focus was on supplying pre-cut composite textiles and papers for the book binding and printing industry. But around 2007, due to the rise of e-books and other technologies, which were threatening printed books, we saw that we needed to diversify our technology and find other markets. We used our skills and experience in cutting difficult-to-cut textiles in book binding to the processing of composite materials. It was quite a big leap! But we looked at our core strengths and saw that the problems our technology solved in book binding presented themselves with composite materials as well. So, we used the experience we’d already built on and transferred it to a different product. These days, our focus is composites.

What’s unique about the cutting/slitting process?

Over the years we’ve developed our own proprietary cutting technology using our knowledge and experience of cutting composite materials from 2007. We’ve used our experience to build bespoke machinery with our own cutting tools, and, with new developments in composites such as the rapid growth of improvements to thermoplastics and carbon fiber tapes, we are still continually developing our cutting technology to match how quickly the industry develops. Our tools are important but our knowledge and experience in developing these cutting tools are also an important part of our technology.

What are the challenges in cutting fiber composites?

The challenge over the years has been all about learning how to handle different composite products with different resins, different fibers and fiber weights. Our end users want a clean cut within the specified tolerances and the correct format. To some people it may sound easy, but the different resin systems in and fibers can cause problems and be a real challenge – not just thickness, but also how the fibers are consolidated. Recently developed materials such as thermoplastic carbon fibers, thermosets, prepregs, and so on, can prone to fraying or producing fuzz. With different epoxy resins, you can have different levels of impregnation – with some prepregs impregnated more than others.

Do you calibrate the cutting machinery according to the client’s requirements and materials?

Yes, especially at first when we were doing a lot of initial development work. However, we’ve been working with our customers for quite a few years now, and we have the knowledge and the dataset about how to run their materials.

What’s trickier to cut – the fiber or the resin?

I’d say that slitting different fibers can be a challenge, especially achieving a consistent clean cut without fuzz or fraying. But thermoplastics can also be tricky, as they can affect some of the characteristics of the carbon fiber when it’s cut. We obviously have to change our process to accommodate for specific materials, such as prepregs, tapes or technical textiles.

Do you sometimes have to ‘mend’ materials that have been badly cut?

We’ve had one or two clients who have tried cutting it themselves, or they’ve gone to companies who aren’t experienced in slitting composites, who have made a bit of a hash of the material, that needs putting right. One or two of our customers have tried buying some cheaper materials which require extra preparation before they can be cut. So, we’ve done a bit of salvage work in the past. Obviously, if a customer cuts a material too small, we can’t make it any wider. But we can reprocess and re-cut and re-blend the material to fit to the format a customer can use.

Who are your main end users?

We work with a lot of prepreg manufacturers as well as providers of dry fibers and multi-axial fibers, and I’d say the bulk of our customers currently are involved in aerospace. Sometimes we deal directly with OEMs, and over the past few years, we’ve worked quite closely with research organizations such as the National Composite Centre.

How do you think Bindatex’s technology will develop?

We’ve just been awarded a Made Smarter grant from the UK government to help further digitize our production systems, and I think this is an area which will develop. We’re looking into monitoring the performance of our machines and the materials passing through the slitting lines. With regards to the development of composite materials, an area we have been involved in for a few years now is thermoplastic UD carbon fiber materials.

Can the cutting process make it easier to recycle composites?

Not directly, but we are looking into ways of recycling the waste trims produced in the cutting of carbon fiber thermoplastics. We’re in some early talks with our customers about what we can do with their in-process waste. I think, as the volumes go up in the processing of thermoplastics, we will find an outlet for recycling the waste, especially when we get definite figures about how much waste is being produced.

How are you planning to grow the company?

Growth is one of our key focuses, and we’ve grown quite rapidly over the past three years. One particular area where we can see growth potential is in the development of very narrow precision slit tapes. We’re currently the only company that can offer a service to slit thermoplastic carbon fiber tapes to 1 mm wide. But, in general, we want to develop our process of precision slitting carbon fiber prepreg, both thermoset and thermoplastic. We also aim is to become a preferred slitting provider on future aerospace projects.

How will Brexit affect the company?

No one really knows what’s going on! But I think UK composites in general are in a better position than other industries in the UK. And because Bindatex offers a niche bespoke service, I think that’ll help us to keep our EU customers. So, I don’t think Brexit will affect our growth plans really, because of our position in the industry.


This article was first published in June 2020.