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Products and solutions, 2009-12-08, 11:25 AM

“metaklett”: New high-performance hook and loop fastener made from ThyssenKrupp Nirosta Präzisionsband stainless steel

Success "sticks" to Velcro: Since it was first registered for patent by the Swiss inventor Georges de Mestral in 1951, the hook and loop fastener has become a commonplace item, used to fasten everything from clothing and shoes to bandages to wiring sleeves in cars. And now it has been taken a stage further. A hook and loop closure made of temperature-resistant stainless steel has been awarded this year's Steel Innovation Prize by the German Steel Industry Association. The material for this new invention is supplied by ThyssenKrupp Nirosta Präzisionsband GmbH in Schalksmühle.

Flexible, easy to use and long lasting: Velcro strip has established itself as an invaluable fastener in a wide range of applications. These have been limited by the material from which it is made – usually plastic, which makes it unsuitable for use in hot environments or where it might come into contact with chemicals. That's why hook and loop closures have never previously been used in the engine compartment of vehicles. This could all change with the innovative new Velcro fastener made of stainless steel, developed by employees of the companies Reinz Dichtungs GmbH, Neu-Ulm and Hölzel Stanz- und Feinwerktechnik GmbH & Co. KG, Wildberg. Under a project managed by Reinz-Dichtungs-GmbH, the cooperation partners came up with various fastener geometries and investigated their manufacturing and joining behavior at the forming and foundry faculty of Munich Technical University. "metaklett" is the first hook and loop fastener made of metal. It offers all the advantages of a Velcro system combined with the strength of stainless steel.

"The challenge was to find a material which is strong and at the same time very flexible to achieve the required hook consistency," says Kurt Höhe, head of advance development and technology at Reinz-Dichtungs-GmbH. Like the plastic variant, "metaklett" consists of two strips, one with loops and one with hooks. When they are pressed together, the hooks and loops engage. The closure is opened by pulling the strips/components apart (shearing/peeling) with the result that the hooks are released from the pile. Kurt Höhe: "After they are disengaged from the loops, the hooks must return to their original shape to ensure that the closure can be used many hundreds of times with no loss of performance". Hölzel Stanz- und Feinwerktechnik now has the job of manufacturing the metal hook and loop closures. The joint invention has already been registered for patent.

The search for the right material led the developers to ThyssenKrupp Nirosta Präzisionsband. “The spring properties of the material Nirosta 4310 meet all requirements in terms of strength and flexibility. After strain hardening, Nirosta 4310 acquires ideal properties for applications subject to alternating loads. In addition, the material is suitable for stamping, embossing, flanging and profiling, and is therefore the optimum choice for the production process at Hölzel Stanz- und Feinwerktechnik", says Heiko Wilken from the ThyssenKrupp Nirosta Präzisionsband sales team.

Two "metaklett" variants are available: "metaklett Flamingo" and "metaklett Entenkopf" (duck's head), with the names referring to the shape of the hooks. Both variants comprise a 0.2 mm thick hook strip and a 0.2 mm thick punched or stamped pile strip of stainless spring steel. They are resistant to chemicals and can withstand tensile loads of up to 35 metric tons per square meter even at 600°C. Despite this strength, the closure can be opened and closed quickly without the use of tools, like a Velcro fastener. A further variant combines a stainless steel hook strip with a plastic pile strip. "metaklett" is suitable for all applications requiring a secure fastening which can be opened easily when required, e.g. for attaching ventilation and cable ducts in buildings or heat shields in the auto industry.

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