Fasteners and Sealing
Sticking with it
4 Clever design and clever chemistry have helped to develop ways of fastening that could revolutionise the way that components are put together. Lou Reade reports.
4 Une conception et une alchimie ingénieuses ont contribué à développer des moyens d’attachement qui pourraient révolutionner l’assemblage des composants. Lou Reade témoigne.
4 Ein intelligentes Design und intelligente Chemie haben dabei geholfen, Arten der Befestigung zu entwickeln, die die Art, wie Bestandteile zusammengesetzt werden, revolutionieren könnten. Lou Reade berichtet.
A
Fig. 1. Fraunhofer is using polylactic acid as the basis for a series of new pressure- sensitive adhesives in industrial applications.
dhesives cannot be made much stronger or stickier than they already are, while mechanical fasteners would seem to have come as far
as they can. But a series of new ideas could breathe new life into products that need to be fastened or stuck together. UK-based Rotite, for example, has
developed a novel connector technology. Two flat discs - each with a raised ‘pattern’ on its surface - are twisted together to make a secure connection. The company’s founder and technical
director, Stuart Burns, says that the concept could be used across a range of industries - from aerospace and defence through to cosmetics, medical and even DIY. The two discs can be identical, or ‘male
and female’. They are pressed together and rotated, by anything between 10 and 360° to form a firm connection. Burns describes the concept as a ‘low profile helicoidal dovetail’. Examples of potential applications include:
attaching a walkie-talkie or radio to a soldier’s tunic; securing under-bonnet automotive components, such as hoses, quickly and effectively; and as a replacement for buckles or clasps in a variety of clothing and textile applications. Burns works to a simple design mantra:
“Get it off the screen and into your hand as soon as possible.” He says that 3D printing has played a crucial role in the development - acting as both a prototyping and a manufacturing technology. “It’s the cornerstone of our technology,”
says Burns. “Without 3D printing we would not exist, and the idea would still be on the shelf. There’s really no way to ‘draw’ the concept - it’s impossible.” As well as being a visualisation tool, he
says it also acts as a ‘thinking tool’ - helping to accelerate understanding of the concept. “This is a novel geometric concept,” he
says. “To get an object and play with it helped us to understand the geometry and to know where the development may go.” The company has looked at a variety of geometries. Some, for example, require a small twist, while others require more rotation in order to ‘lock’; some have identical faces, while others connect two different faces; others can incorporate added functionality, and do not always have to be ‘flat’. In addition to the expected ‘male’ and
‘female’ geometries, Rotite has also developed ‘hermaphroditic geometries’. “These are previously unimaginable geometries,” says Burns. “As we’ve played with the 3D shapes, this helps to stimulate the design process. As we went on we looked at extra functionality. To start with it was just a mechanical interface. We then realised there were other areas to look into, like locking mechanisms and switches.” Rotite has filed a UK patent, and is looking
to license the concept. Burns says that the company has taken the last three or four years to develop as many variants as possible. “If we’d rushed straight to market we
would have had one or two examples. Instead, we have hundreds - all of them quantified by 3D printing. There are so many variables that we can’t possibly understand where they will all go,“ he says. “There are so many opportunities: I’m very excited about it.”
Best foot forward
US scientists have created micro-scaled polyurethane (PU) structures that mimic the way that a gecko’s foot sticks to a surface.
www.engineerlive.com 29
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