Adhesive technology on the up
The Shard has redefined London's landscape. It towers over the Gherkin by 130m and is almost twice the height of any other viewing platforms in London. Indeed this masterpiece of architecture is now the tallest building in Western Europe and naturally passenger lifts play a very important part in its daily life. They travel skywards at a dizzy six metres per second and, in common with many new lift installations across the world, the structure of its cars is bonded with Henkel adhesives.
Double-deck lifts are a feature of the Shard. Two cars, one on top of the other, allow passengers on two consecutive floors to use the lift simultaneously. The design substantially increases passenger capacity in the lift shafts. Henkel adhesives bond the door assemblies of cars, offering a number of design and performance advantages.
Increasingly, high performance adhesives are replacing traditional joining technologies such as riveting, welding, clamping and bolting. This trend is across a wide range of industrial sectors and passenger lift construction is no exception. And there are a number of reasons for their popularity. From a design standpoint adhesives offer far superior stress distribution over large surface areas and those exposed to high loading. This has a very positive effect on the static and dynamic strength achieved by comparison with welding and riveting which result in localised stress peaks. Welding temperatures may also change the structure and therefore the mechanical properties of materials.
Adhesives act as sealants, preventing loss of pressure or liquids, blocking the penetration of condensation and protecting against corrosion. Additionally, they form an insulating film, to prevent contact corrosion when different types of metals are joined. Adhesives are also excellent electrical and thermal insulators.
Weight reduction is another important benefit of adhesive technology. Through the use of adhesives alone, up to 20% can be saved on the weight of a standard lift, mainly because thinner and lighter materials can be used without compromising performance.
The adhesives stiffen and stabilise the assembly when used in combination with appropriate joint design. The introduction of an omega profile, for example, that is bonded to the outside face of the panel considerably enhances the strength of the structure.
The lower the weight of the car the more cost efficient it is to run. This has made structural adhesives the preferred method of joining for the latest generation high speed lifts around the world. The technology allows faster acceleration and travelling speeds. The current record-holders are the Taiwanese who have lifts that propel their passengers at a speed of 60.6km per hour, corresponding to 16.8m per second.
Another important factor for this area of application is aesthetics. The 'look' of the Shard is one of its many qualities and its lifts must complement the overall design. As adhesives do not change the surface of materials, cosmetic rework isn't necessary. If panels are bolted or welded, the joints are traditionally covered by cladding. Not only does this add another production process, it also increases the weight of the car.
The benefits of using adhesives are not just restricted to speed, lower energy consumption and visual appeal however. They also pave the way for an increase in payload potential, an important factor in maximising the number of passengers and also for carriage of goods in service lifts.
Motor design is another beneficiary of adhesive technology. The clips and clamps that were once used on components such as rotors and stators are increasingly being replaced by adhesive-bonded magnets as the preferred method of fixing. Improved motor performance and service life have resulted thanks to a reduction in vibration. Motors also have greater resilience to thermal stress and shock.
Whilst metals remain predominant in lift construction, other materials are increasingly being incorporated. Glass, plastics as well as painted and powder coated surfaces are becoming more commonplace and the ability of adhesive technology to bond dissimilar materials such as these allows unconventional material combinations to be considered.
The lighting industry also benefits from modern adhesive technology. New formulations have been developed for LED installations which, when used in lift construction, further enhance the energy efficiency credentials of the design.
In Europe alone, around 100,000 lifts are installed in new buildings and refurbished premises every year. Structural bonding is playing an increasingly important role in the design of these projects and it's easy to understand why. As well as providing important performance and cost saving benefits, adhesives also considerably extend the potential for creative design.
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