When specifying a trim and earth attachment stud 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 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.
Also the heat 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.
Faced with these design constraints, and aware of Henrob’s revolutionary self-pierce riveting technology in use at other automotive manufacturers, Aston Martin's designers and engineers teamed up with Henrob to develop a self-piercing version of the threaded stud, in both M5 and M6 variants, that would cope with the demands placed on this type of fastener in auto body applications.
The result is Henrob SPS (Self-Piercing Stud) technology, comprising the studs themselves and a new range of StudTrans fastening systems for delivering and installing the studs.
Over 200 Henrob self-piercing studs are inserted in each DB9 body in a simple one-shot process that does not need any pre-drilled hole and is quiet, clean and repeatable.
As the process does not generate any heat, the anodic coating on the panels remains intact, thus preventing corrosion and ensuring Aston Martin’s deserved reputation at the pinnacle of automotive quality and performance.
In terms of performance the Henrob self-piercing stud excels, with an installed torque resistance of approximately 16Nm (M6 thread), and an electrical resistance of less than 100µO, the Henrob self-piercing studs can be inserted into aluminium or steel panels, from 1.2mm to 3.0mm thickness.