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Steel sandwich elements – one technique, many applications

Kenno Tech’s laser welding and steel sandwich element technology is a great way to manufacture highly efficient heat exchangers, as well as ballistic protection structures and countless other applications.

Depending on the specific requirements of an application and working in close cooperation with a customer, Kenno Tech can manufacture heat exchanger elements using either conventional sandwich elements or what are known as inflated plates.

The latter are produced by laser-welding two steel plates together using a flow channel pattern and then employing hydraulic pressure to inflate the plate – in a process a little like inflating an air mattress at the beach or by the pool.

Kenno Tech is capable of manufacturing industrial heat exchanger elements for use in industrial process control and/or for collecting heat energy up to approx. 10 metres long and three metres wide.

The thickness of the sheet steel used is determined by the operating parameters specified for the unit, and can result in panels able to withstand up to 100 bars of pressure.

Sandwich structures can also make highly effective ballistic shields, as the recently developed KSJ Element System shows.

Modular protection that’s quick off the draw

Drawing on a research project that involved experts from the Finnish Defence Forces, Rautaruukki, and VTT Technical Research Centre of Finland, Kenno Tech’s modular KSJ System offers a fast-to-erect ballistic shield system. Using the system, a camp wall or a shelter can be erected in hours instead of days by as little as three men and provide protection against ordinance up to 155 mm artillery shells.

The patent-pending KSJ System consists of seven wall elements, each six metres long, which can be stacked and transported as a selfsupporting equivalent of a 20 ft. sea container. Unloading and assembly takes just a couple of hours with nothing more than a front loader tractor or hoist and results in 42 metres of armoured wall for a camp or a covered shelter.

The KJS System also includes the KSJ Container, a protected 20 ft. sea container designed for use as a personnel shelter or secure storage for equipment and supplies.

Laser welding is ideal for manufacturing these elements, as it does not destroy the hardness of the steel even along welding seams, while the sandwich structure is more efficient at stopping bullets and fragments than a uniform steel plate of equal thickness. The space between the faceplates can be filled with sand or gravel to provide increased protection.

Laser welding expert

Kenno Tech’s laser-welded sandwich elements offer light weight, durability, and bending strength equivalent to that of much heavier conventional structures. This has seen them used in a myriad of applications, from lift floors and insulated wood kiln doors and walls to tourist information kiosks, concrete moulds, and hoods and hatches.

A KSJ Element System ‘twin-pack’ ready to go, sufficient for 84 metres of camp wall that can be erected in just a couple of hours.
> Jouko Vallikari
(Published in HighTech Finland 2013)