A smarter fix

Driven by the need for security, increasingly stringent recycling
regulations and above all a desire to innovate, new exciting fastening
solutions are beginning to emerge.

Ask the average person to say something interesting about fasteners and you’ll typically be treated to a pun involving the word rivet. The fact is that fasteners – the ubiquitous, unobtrusive workhorses of the industrial world – have never really set the world alight.

Until now.

Driven by the need for security, increasingly stringent recyclingregulations and above all a desire to innovate, new exciting fasteningsolutions are beginning to emerge.

These technologies, in which fasteners can be unlatched in response to a signal from the modern-day equivalent of a Doctor Who? sonic screwdriver, not only threaten to banish the wrench and screwdriver. But they could also change forever the way that products are designed, assembled, serviced and recycled.

Chief among these developments is an Intelligent Fastening Technology (IFT) recently introduced by US company Textron. Based on a concept invented by Australian technology licensingcompany Telezygology, Textron has developed mechanical fastenerswith embedded chips that can be remotely operated using a hand-held device.

These devices exploit the unusual properties of shape memory alloys – a group of metals that can be severely deformed but will return to their original shape when heated.

Seshu Seshasai, Textron’s executive vice-president of technology, explained the basic principles behind their operation.

A typical fastener contains two springs made from a shape memory alloy and an embedded chip. A hand tool is used to send commands to this chip, which induces the flow of a small electrical current in either of the two springs.

This current causes the springs to heat up and revert to their remembered shape. The springs control the position of a tiny piston that will either restrain or free the movement of the clips of the latch. Depending on which spring is energised, the fastener will be latched or unlatched.

Clearly, few, if any, assemblies are held together by one fastener and perhaps the cleverest thing about Textron’s system is the ability to network groups of fasteners. In a typical application, explained Seshasai, one fastener would be equipped with a master chip containing a processor, while others simply have slave chips that take their lead from the master.

Obviously fasteners equipped with this kind of technology are going to be more expensive than their primitive forebears – around 20 times more expensive, according to Seshasai. But, for the kind of high-end applications that Textron is initially targeting, the advantages, he said, will far outweigh these costs.

Arming the once humble fastener with this level of intelligence opens up a range of possibilities. ‘These things offer so many more advantages than “dumb” fasteners, said Seshasai. ‘They can send signals, they can keep a record of maintenance, and they will allow only authorised people to operate them. Security becomes very easy to manage.’

Plus the master chip can even be programmed to send out a signal if a fastener becomes loose, he added.

Seshasai also stressed that each fastener has its own unique serial number, meaning that commands can’t be confused and you won’t find yourself accidentally dismantling your motorbike while trying to repair your own fridge.

As for applications, the technology could be used everywhere conventional fasteners are used – from circuit boards to washing machines to passenger jets. The most immediate area of interest, though, is likely to be in the high-end automotive sector.

One prototype application recently demonstrated by Textron is a tamper-proof fastening system for car airbag modules. Air-bag theft is a big problem in the US – with more than 50,000 airbags stolen each year. In a prototype system on a production vehicle, an airbag is attached to the car by fasteners that will respond only to remote instructions entered by an authorised individual.

As well as the security advantages of embedded intelligence, the technology opens up some exciting possibilities for designers. Since the fasteners are remotely operated, they don’t need to be within the reach of a screwdriver or wrench, and can therefore be located just about anywhere on an assembly. ‘They can be totally hidden,’ said Seshasai. ‘They will simplify the shape of products, create nicer-looking products – if you don’t need access to the fastener you can really change product design.’

There are clearly many, many interesting applications, but we may have to wait a little longer for full-blown commercial applications, said Seshasai. The reason for this, he explained, is that the technology is not simply a replacement for traditional fasteners.

One of its biggest advantages is that it will enable designers to fundamentally change their designs, and manufacturers to fundamentally alter their assembly processes. To take full advantage of the technology manufacturers must really look at incorporating the technology in their next-generation vehicles, said Seshasai.

Bound by non-disclosure agreements, Seshasai was unable to name names but said that Textron is currently discussing the technology with a number of major manufacturers, and hopes to have commercial applications in the air and on the road by the end of next year.

Clearly another benefit of this kind of technology is that it enables products to be recycled easily. Rather than being clumsily dismantled with a screwdriver, they can be taken apart in a non-destructive way, thus maximising the potential for reuse and recycling.

Brunel University spin-out company Active Fastener recently unveiled a technology designed to enable exactly that. The system – where the application of heat causes snap-in fasteners to shrink and the assembly to come apart — is being developed in direct response to the impending EU waste and electronic equipment directive (WEEE).

This legislation, which will affect manufacturers from August 2005, will essentially force them to pay for the recycling of their own products.

Habib Hussein, technical manager of the company, believes that ifmanufacturers embrace his technology these recycling costs could besignificantly reduced.

Hussein’s team began by looking at the use of shape memory polymers and alloys – where under the application of heat a fastener assumes a ‘remembered’ position and becomes unlatched. But despite the elegance of this approach the technology has a number of drawbacks. Shape memory alloys are expensive, it’s difficult to form them into complex shapes and, with few proven commercial applications and even fewer suppliers, Hussein said that fastener manufacturers would be wary of throwing their weight behind the technology.

Thus, without completely writing off the use of more exotic materials, the company has turned its attentions to a simpler and less expensive solution that exploits the existing ‘shape recovery’ properties of traditional engineering polymers such as PET, ABS and polycarbonate.

It’s commonly known that if you expose standard thermoplastics to heat they shrink, yet Hussein claimed that this property has never before been exploited in commercial disassemblysystems. He added that he is currently talking to a number of material suppliers about tailoring the shape recoveryproperties of traditional plastics.

At present disassembly would be done manually – for a mobile phone, for instance, this could take up to five minutes. But according to Hussein, while his technology would improve on this time, its chief advantage is that ovens or hot-water baths could be used to disassemble large batches of different products.

Further research will look into the development of other trigger methods such as hand-held microwave and infrared tools for targeting specific parts of a product. This, he explained, will further reduce the amount of energy required to disassemble a product and thus lessen the environmental impact of the technology.

While prototype systems have proved the basic concept, the next step, said Hussein, is to drum up more funding to carry out research into the long-term stability of active fasteners and get some manufacturers involved.

Predictably, though, environmental concerns alone are not a compelling enough reason for manufacturers to adopt the technology. To really catch on, it must be profitable, and this, said Hussein, will depend on the way the WEEE legislation is policed.

Nevertheless, Hussein is encouraged by what he’s hearing from the industry, and has even had to turn away a few customers wanting to buy a product that does not yet exist. Depending on funding, this situation could soon change, and Hussein hopes to have a product on the market by the time the legislation comes in.

However, amid all the benefits of intelligent fastening technology – to manufacturers, consumers and the environment – one potential disadvantage emerges.

If the technology fulfils its potential, simple hand tools such as the screwdriver and wrench will ultimately become redundant – and if consumers want to repair and maintain their own appliances then they will require more expensive electronic hand tools. And that will depend on the appliance manufacturers passing up a goldenmoney-making opportunity, and making these tools available to theconsumer.

Textron’s Seshu Seshasai thinks this scenario is unlikely. Modern cars, with their on-board computers and impenetrable bonnets, are already a no-go zone for the amateur mechanic, but for simpler home appliances where security is not an issue he envisages consumers being able to purchase a tool that can be used throughout the whole house.