Fasteners & Sealing


the automotive OEM supply chain, as this increases the demand for associated components, such as robust fastening mechanisms. These fasteners must allow both rapid and easy installation on the assembly line, yet also enable subsequent fast access for post-assembly servicing. Southco claims a leading position in the supply of


equipment to tackle the access demands of this growing automotive sector with its range of Dzus quarter-turn fasteners, which offer an effective replacement to conventional threaded fastening devices and meet the underbody and protective shield requirements of today’s cars and trucks.


Resistance to vibration


The key benefits of Dzus quarter-turn fasteners include resistance to vibration, fatigue and temperature changes, resistance to corrosion, and the choice of a variety of head style options. And Dzus fasteners can be simply secured to steel, aluminium or composite chassis underbody components through pre-punched holes. Ulrike Sturman, industry marketing manager for


transportation at Southco, explained: “There is a perpetual contrast between fasteners based on traditional screw thread systems and those based on quick-release mechanisms. It has long been perceived that, for a robust and durable fastening system, threaded fasteners offer the most cost-effective solution.”


Although a threaded system might be cheap to buy, the


time it takes to lock and unlock the system makes it expensive in terms of initial installation. “The recovery gains of the Dzus quick access quarter-


turn system, made from reducing the time it takes to install and then from future access needed for servicing more than outweighs the upfront investment,” Sturman added.


More recently, the company has developed a range of new quarter-turns and accessories. These include a stud that has an orientated head feature to cam. This brings the added benefits of the head feature always engaging and locking in the same position. The lock position of panel fasteners can therefore be identified, and installation time is speeded up.


Self-piercing technology


Moving away from steel panels does present an assembly challenge for motor manufacturers as spot welding, possibly the most common joining technique used in car assembly, is at best problematical when assembling light alloy or composite materials. An alternative system to replace welding of lighter


materials is the self-piercing rivet (SPR). In its crudest forms, self-pierce fastening has been around for hundreds of years; compare it to the traditional hammer and nails. The system has developed over the past few decades and this versatile and efficient fastening process is certainly one to watch in the future. The SPR technology originated in Australia and was


invented at a Brisbane University in the mid-1970s. Keith Jones, who is the owner of fastener supplier Henrob, was out in Australia on a business trip and came across the technology. Jones saw the technology as a real business opportunity so purchased the intellectual property and brought it back to Europe for further development. As a leader in this field, Henrob is committed to pushing


the boundaries of SPR technology. According to Henrob’s Phil Halsall, there is an important


difference in service life between a pre-drilled and riveted joint and one that is joined using SPR. The fatigue life of the SPR exhibits a tenfold improvement over the blind fastener and


Self-piercing threaded stud A


ston Martin’s designers and engineers teamed up with Henrob to


develop a self-piercing threaded stud that would cope with the extreme demands of auto body applications. Aston Martin’s DB9 has a body


structure fabricated from high- strength aluminium alloys and exotic aerospace composites, and it is every bit as impressive under the skin as it is on the surface. When specifying a trim and


earth attachment studs, the designers at Aston Martin were faced with serious challenges in finding a product that fulfilled all of their stringent design criteria. The studs had to be fixed to anodised


Fig. 4. More than 200 self-piercing studs are inserted in each DB9 body.


aluminium panels, which meant that welding was out, as the difficulty of welding through


the anodic film would prevent the studs from attaching properly to the panel. The head generated during welding would have locally damaged the anodic film, thus


compromising the anti-corrosion performance of the body structure. The studs also required a high


degree of electrical continuity, so they could be used to earth the many electrical components attached to the body structure. This meant that adhesively bonded studs could not be used, as little current would pass through the adhesive layer between the stud and the car body. As heavy items of in-car equipment would be attached to the body using the studs, the studs required a high degree of mechanical strength, torque and vibration resistance. Over 200 Henrob self-piercing


studs are inserted in each DB9 body in a simple one-shot process that does not require pre-drilled holes, is quiet, clean and repeatable. ●


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