Latest twist on composite connections

Written by: Tim Fryer | Published:

Back in 2012 Eureka covered in an interesting development in fastening technology called Rotite. Getting new technology adopted, particularly when it is primarily aimed at the aerospace and automotive industries, is not easy though, but now the company could be at an inflexion point.

“The SMMT [Society of Motor Manufacturers and Traders] have determined that you can't make cars light enough using traditional means, if you're going to meet all of the emissions targets that have been set. So now there's a countrywide determination that we have to make vehicles lighter,” stated Stuart Burns, managing director of Rotite Technologies and inventor of the system that bears the company’s name.

Burns describes the principle behind the Rotite system as connecting two items together with a geometric configuration based around helical interacting items. He explained “It was originally based around a dovetail cross-section, and it's often been described as a helicoidal dovetail. Dovetail is just one of the interlocking profiles it can use.Some people have called it the flat screw. It is thread technology applied but in a different plane, and with limited rotational extent.”

But among the problems of having developed a fairly fundamental technology, are firstly gaining acceptance in ultra-conservative, safety critical industries, and secondly providing comparative data that is meaningful to engineers more accustomed to using more traditional fixing methods, like nuts and bolts. On top of this, Rotite is a technology rather than a specific product and it can be adopted in a limitless range of shapes and sizes.

These problems have shaped progress over the intervening years since Eureka’s first report. Burns said: “One of the things that we've been doing recently is refining the technology. Because when we talk to engineering companies, and there are potentially limitless derivatives, it can be a little confusing as to what the core system is. So part and parcel this aerospace technology programme we are on, is we're working on standardising those geometries.”

Refining technology

The logic is that if an engineer was using traditional fastening methods, say an M10 or M12 nut and bolt, there is standard specification about size, loads, manufacturing tolerances and so on. Rotite is now going through the process of creating the necessary core geometries to make the system equally specifiable.

More so it needs to be comparable. “If you're going to teach people the language of Rotite, then you have to have parity with something else, like nuts and bolts,” stated Burns. “The idea of communicating the tensile qualities, shape qualities of an interface - this is kind of exactly what we've done on the previous Innovate UK funded programme, which they seem to perform a standard range of tests such as those that you would in any other fastening system. What we've had to do is basically refine down the technological prospect and then give it the validity.

“I would get an invitation to spaceship companies and Formula One teams and while everybody wanted to use Rotite, there was the need for the science behind it, the technological validity."

The Innovate UK funding Burns mentions was part of the ‘snowball’ that has led to collaborations with some leading aerospace companies. Innovate UK funding attracted investment, which allowed Rotite to get into the NATEP programme (National Aerospace Technology Exploitation Programme) allowing it to rub shoulders and have meaningful conversations with the likes of Airbus.

Beyond aligning the technology for the market, product development has also not stood still. Burns said: “What we are doing is forming consortia to provide novel, lightweight fastening systems for contemporary materials.” The materials in question are the composites that are the focus of many automotive and aerospace developments. Drilling holes in composites can seriously affect their integrity, so traditional fastening techniques, apart from adding weight, can also introduce engineering problems. The advantage of Rotite in such an environment is that the fastener can be moulded into the part, therefore requiring no further fastening components.

It is not work that a fledging company of Rotite’s size could embark on on its own, as Burns explained: “The Northwest Composite Centre at Manchester University has two sections. It is at the basic NCC where we are working under the NATEP programme – they are the facilitators of our composite development programme. But there is also the NCCEF, which is the National Composite Certification and Evaluation Facility, and they are our test house, basically. I have some large, metallic objects that strain Rotites there, they do the assessment and validation of our various Rotite forms.”

Being a newcomer to the fastening world has made such alliances essential. In fact although essentially an IP company (although off the self products will be introduced within a year) one of the more productive routes to market is through the company’s technical consultancies, who explore with potential customers how the technology could be applied.

“One of the things that we often find in our technical consultancies, is Rotite can actually do things that people don't expect, which sounds a little far-fetched,” commented Burns. “It can do a number of different things at the same time as fastening two items together. For instance, electronics in composites - making conductive connection systems.”

This example is being pursued with Graphene Enabled Systems, the commercialisation arm of the National Graphene Institute which is also at Manchester University. They are exploring the options of having multi point connections depending on the degree of rotation as well as making the whole joint out of homogenously conductive materials.

The work with graphene is one of the areas in which Burns sees huge potential: “As an additive to polymers, graphene can make things stronger, conductive, more wear resistant, and there's the prospect of light-weighting items. In terms of aerospace and automotive fastening technologies, it's a very, very viable prospect.”

Other sectors are starting to recognise some of the other benefits of the system. For example, the design team is growing to deliver a range of products for the sports and leisure technology market. To this aim Rotite has recently embarked on a supply chain partnership with Albis UK – in innovative polymer supplier. Products will be on the shelves very soon

Another prime example is with manufacturing machinery. One of the tools in a Lean Manufacturing strategy is SMED – single minute exchange of die. The basic premise is that if tools can be swapped over quickly then less production time is lost.

“It's the idea that if you can design and make things quicker because you've got assembly aids and quick fastening systems and solutions, then it makes you more productive which makes you more productive which makes you more profit, said Burns. “So an awful lot of the interest in Rotite is now about jigging systems, positioning systems and tooling changeover. We've had a number of companies who are developing applications for Rotite, who want it for things like positioning systems and clamping systems and assembly aids. It's that repeatability, the high precision repositioning of things.”

However it is in the high tech arenas of aerospace and automotive thatBurns sees his technology really making its mark. “As we move into an era of advanced materials manufacturing, some of the traditional fastening technologies are just not viable,” concludes Burns. “So we haven't had to convince people particularly of the prospects of developing composite fasteners based upon Rotite.”

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