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A lighter future for structures

In a world of rising steel and energy prices, escalating labour costs, and more complex logistics requirements there is a growing interest in lightweight, material-saving metal structures. Sandwich designs – such as Kenno Tech’s laser-welded elements – offer a highly attractive solution.

The world’s consumption of raw steel rose from 789 million tonnes in 1999 to over 1.2 billion tonnes in 2006, and is expected to grow by 6% annually; while world energy consumption in 2015 is forecast to be 25% above today’s levels. Labour costs are also rising rapidly, and the pressures to introduce more eco-efficient solutions are increasing as well.

Against this background, the traditional method of manufacturing large steel structures using thick steel plating and welded stiffener beams is becoming outmoded. Industry’s interest in structures utilising thin sheet metal is on the rise to address today’s new challenges, and tomorrow’s.

The benefits

Sandwich structures are a particularly attractive solution for large panel elements. Kenno Tech’s laser-welded sandwich elements, for example, offer light weight combined with durability and bending strength equivalent to that of much heavier conventional structures.

It is also easy to optimise these sandwich elements for specific applications by varying the thickness of cover plates and cores, the materials used, and the shape of the core.

Compared to traditional steel structures, this approach can yield steel savings of between 30% and 50% and reduce weight by the same margin. Very stiff structures with low structural height can be achieved, and can be designed to be self-supporting. They can also incorporate insulation, electrics, and plumbing. In addition to steel, the same technology can be used to create aluminium sandwich structures.

Laser welding is not only very fast, it also makes it possible to use very thin steel – down to 0.3 mm thick. Distortion is minimal, giving high dimensional accuracy. Welding seams are thin and very uniform along their length, resulting in high finish quality. And being of all-metal construction, recycling is easy as well.

Great for lots of applications

Thanks to these multiple benefits, Kenno Tech’s sandwich panels are ideal for numerous types of applications.

In one recent example, for example, it proved possible to increase the payload of a vehicle elevator by 1,000 kg thanks to the use of a sandwich element floor. A lighter counterweight could also be used, and assembly was easier too.

The material savings typical of Kenno Tech technology are particularly significant in stainless steel applications, and sandwich elements are well-suited for fabricating hoods, hatches, and other areas of process machinery.

Stiff sandwich floor elements are a good solution for prefabricated instrument or machinery units that can be assembled off-site and delivered on a ‘plug and play’ basis. Sandwich structures also lend themselves for use as ballistic shields.

Kenno Tech designs and manufactures laser-welded sandwich elements, and provides consultancy services on production technology and applications.
> Jouko Vallikari
(Published in HighTech Finland 2008)