Forward with fastening

Tom Shelley reports from market leaders on the rosy future for fastening and joining

An indication of the potentially rosy future for the technologies of fastening and joining can be deduced from the expansion plans of TWI, formerly known as The Welding Institute and widely regarded as the world's leading centre of research expertise on the subject of fastening and joining. Following on from a study called Vision 2020, £17 million is being invested in new and improved facilities at it headquarters site at Abington near Cambridge, and new regional offices are being sought in Yorkshire and Wales. Dr Dave McKeown, TWI’s marketing manager, says the study not only concluded that "joining in its widest sense will remain a viable technology for the foreseeable future" but that "the whole subject area will broaden". New challenges will emerge, such as the need for the automotive industry to continue its weight reduction exercises, with hybrid bonding likely to grow at the expense of brazing and welding. And all kinds of materials, such as magnesium, composites and polycarbonate, will need to be joined to structures which may be aluminium alloy or high strength steel and then disassembled in the soon to be required 'cradle to cradle' concept of recycling. New opportunities are emerging, such as the growth of the medical market, which Dr McKeown sees as having the ability to benefit significantly from an increased input of ‘traditional engineering’. He cites the examples of improved welding to eliminate leakage from colostomy bags, finite element analysis of stents to hold arteries open, improved surfacings for hip joints and rings of coating on biopsy needles. The purpose of the latter is to react with body fluids and produce a small amount of gas, rendering the needles easier to see in real time X-ray imaging. Surrounding TWI is the detritus that marks the construction and development of the Granta science park which is dedicated to the health sciences and biotechnology, A fifth of this new science part will be owned by TWI and tenants already include a least one company devoted to making cardiac sensors, and synergistic interests could well cause this side of TWI's business to grow rapidly. However, the oil, gas and chemical industry team is still the largest by budget. But whereas one of its main former businesses was in constructing new oil platforms, it is now focussing more on pipes and life extensions of existing platforms. This is especially true now that these can no longer simply be scuttled, but have to be cut up and recycled if they are no longer of service. Similarly, there is little interest in the UK in building new nuclear power stations, but a great deal of work is having to be undertaken to discover safe ways to contain radio-active waste and developing processes such as a laser technique for 'scabbling' the surface layers off irradiated concrete. Totally new market sectors are emerging, too. One of these is the 'Clearweld' process for laser welding optically clear plastics by adding an infra-red laser light absorbing dye. Originally developed for welding plastic packaging, it has since led to a spin-off process for welding fabrics. Fabrics, being woven, are largely holes, but placing a layer of Clearweld between the layers absorbs all the infra-red laser light, and permits the welding of outdoor garments to make them waterproof. This points to a way to make flexible liquid and gas containments out of materials that previously could not have been considered for such tasks. Sticking to the future One of the growth areas in fastening and joining is adhesive bonding, and to this end, Henkel Loctite Adhesives has introduced two new adhesives that enable flexible materials to be bonded quickly and neatly. The formulations provide exceptional flexibility and high transparency, resulting in a neat and inconspicuous bond for products such as flexible seals and gaskets, industrial clothing and audio loudspeakers. The new adhesives combine the advantages of cyanoacrylate adhesives with a transparent, impact resistant and flexible bond. Loctite 4850 is a medium viscosity adhesive, suitable for the permanent bonding of flexible and porous materials including paper, card and fabrics used in the manufacture of products such as gaskets and seals. Loctite 4860, on the other hand, has similar bonding characteristics but is intended for applications such as the production, assembly, maintenance and repair of gaskets, gaiters and seals, the manufacture and repair of industrial clothing and footwear, and the bonding of labels and signs. Fastening onto the future Typical of the new generation of innovative mechanical fasteners are self clinching cable tie holders from PEM Fastening Systems. The TY-D mount is placed into a correctly sized rectangular hole and a press used to apply a squeezing force to insert it. It requires no use of adhesives that might fail as a result of temperature cycling and, unlike rough edged lances in a sheet, the mount does not create openings that can result in EMI/RFI problems or contamination of electronics by dust or dirt. It can be placed at designed locations and angles, and will remain permanently installed and secure for the life of an assembly. Since it eliminates screws, it reduces inventory, and since it does not protrude on the opposite site, it does not affect backside clearance or appearance, as is the case with snap-in and screw-mounted bases. After installation, the cable ties slide through the 'eye’ of the fastener for cable mounting. The mount can be installed in sheets as thin as 1.5mm and as thick as 3.2mm, and is available in several sizes. Mountney, the UK's leading maker of bespoke steering wheels, assembles over 200 types of product using just the one size of fastener. In each case, the spokes are attached to the centre rim using Avdel Stavex 3/16 inch (4.8mm diameter) breakstem steel fasteners made by Textron Fastening Systems. Each fastener has a grip range from 1.5mm to 9.5mm. Challenge Industrial Fastenings boasts that it has taken over and completed a complete component kit supply in just 24 hours. The kit was a domestic security package and included brackets, padlock, screws and mounting plugs. Challenge sources all the components, which tare now procured on an on-going basis. Quality control includes a 100% inspection process. A remarkable number of innovative products depend on BigHead bonding fasteners, which embed in plastic and other materials to spread loads applied via protruding screw and nut elements. Recent developments include specials to allow the fastening of glass reinforced gypsum sound diffusers. Bigheads are even used to allow the articulation of joints in the models on show at Madame Tussaud's. Latching onto the future Southco's M2 compression style push to close latch provides compression with a fractional turn. Once the latch is engaged in the receptacle, turning the latch will pull latch and receptacle more tightly together, applying compression to the panel and frame and/or gasketing material. When latched, ridges on the receptacle line up with grooves on the latch to ensure that it does not vibrate loose. Springing to the future Kato-Entex in Nottingham makes springs that will pass easily through the eye of a needle. Applications include mechanical drug delivery devices such as metered dose inhalers, auto injection systems and nasal sprays. Slipping into the future For those who want to make joints that slip on overload, improvements continue to be made in tolerance rings. Explains Roger Cornwell, sales and marketing manager at Rencol: "Traditionally, tolerance rings have a uniform wave form around their circumference, with the wave form set either on the inside or the outside of the ring. Designs are now emerging, for example, which use fewer wave forms more widely spaced, or which have wave forms on both inner and outer surfaces. Such variations allow performance to be engineered across an ever wider torque spectrum, making it easier to eliminate more complex mechanisms and incorporate torque control devices readily even within tightly designed space enveloped." TWI Dave McKeown PEM Fastening Systems E-mail PEM Henkel Loctite E-mail Henkel Loctite Challenge Industrial Fasteners E-mail Challenge Industrial Fasteners Southco E-mail Southco Kato-Entex E-mail Kato-Entex Bighead Bonding Fasteners E-mail Bighead Bonding Fasteners