Fasteners & Sealing
this is why SPR has been so readily adopted on many body- in-white vehicle applications. Thanks to the technology, the company has a full order
book and can plan with confidence. The market place has changed over the last three years and there has been complete swing in the way aluminium and high strength steel has been adopted in the automotive market place on a global basis and at every OEM. Henrob is determined to keep one step ahead of its competition and continue its rapid expansion. Halsall believes that the company needs to manage this growth and deliver a level of profitability that will allow future investment in the technology development and high production volumes.
Self-clinching option
As materials are formulated to be lighter, panels are made from harder material to maintain their strength. Harder materials are harder to join and as well as being less suitable for welding, they are tougher to pierce. A fastener using a pre- drilled or punched hole overcomes the problem. The PEM nut is an internally threaded fastener, that when
pressed into ductile metal, displaces the host material around the mounting hole, causing it to cold flow into a specially designed annular recess in the shank of the fastener. A serrated clinching ring prevents the fastener from rotating in the host material once it has been properly inserted. Thus the nut becomes a permanent part of the host material offering strong, load bearing threads in relatively thin sheets of metal.
The generic term for this type of fastener
Fig. 3. Launched at the 2012 Farnborough International Air Show, the RivNut Aero combines the benefits of the rivet nut and the strength of the threaded insert.
is self-clinching nut. A current day use of the technology illustrates its benefits over other joining methods. In the German automotive
sector, there is a company producing seat rails for three
of the leading car manufacturers. In recent times, there has been a need to reduce component weight for environmental considerations while retaining strength for safety reasons. This has meant that the seat rail has become thinner but is now made from a harder material so self-piercing fasteners and
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even welding are no longer an option. The result is that the majority of road cars made in
Germany have their seats attached with self-clinching fasteners.
Although primarily intended for the aerospace industry,
an interesting new development from Böllhoff Armstrong is suitable for joining thin plates or non-metallic panels uses a rivet nut to provide the depth of thread required and a threaded insert to provide the required strength and load distribution. The new component was launched at this year’s
Farnborough International Air Show and includes a rivet nut made by Böllhoff in France, with a threaded insert from Böllhoff Armstrong fitted into it. The result is the Rivnut Aero which combines the benefits of both Rivnut and HeliCoil. The user is presented with a high resistance self- locking insert nut which provides a resistant thread on carbon steel and aluminium plates. The design prevents unscrewing and plate sliding and is very flexible in use because of its all- in-one installation kit.
Corrosion resistance
The shank is made of 316L stainless steel, which ensures the necessary corrosion resistance and mechanical characteristics. The HeliCoil Screw-lock helical thread insert prevents unscrewing and plays its part in providing the desired connection performance. The threads can be silver-plated to prevent binding. The design has some real advantages combining the
advantages of blind installation, reliable and reproducible results and possibility of checking the swage quality during the fitting operation with those of the helical thread insert, which include efficient and durable anti-unscrewing to ISO 2320, a high wear resistance of the thread as well as excellent resistance to vibrations and thermal shocks. After the roller coaster ride of 2011, the European motor
industry is seeing a marked upturn in fortunes and despite continuing economic uncertainties in the Eurozone, EU motor manufacturing is forecasting car sales of 14 million in 2012. The manufacturers’ adoption of sustainable designs using lighter materials has certainly been a key element of this success. In their own way the fastener industry has made an equally valuable contribution by developing the joining techniques required for fabrication with lighter materials. l
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