Pierce fastening technology drives vehicle assembly into the fast lane

Citation

(2005), "Pierce fastening technology drives vehicle assembly into the fast lane", Assembly Automation, Vol. 25 No. 2. https://doi.org/10.1108/aa.2005.03325bab.003

Pierce fastening technology drives vehicle assembly into the fast lane

Pierce fastening technology drives vehicle assembly into the fast lane

Keywords: Fasteners, Automotive industry

The motor industry is renowned for its relentless quest for better, more cost- effective manufacturing methods. And with perhaps 30,000 individual components mounted within the structure of a typical modern car, the provision of high strength threads in sheet metal assemblies continues to be a major focus of attention. So, when motor manufacturers set about designing their new models, it is no surprise that they should look for solutions which provide greater benefits than simple rivet or weld type fixings.

Over the past few years, there has been a major shift away from traditional methods – with an explosion in the use of high strength pierce/clinch fasteners to meet both general and “safety- critical” vehicle applications.

BMW Group is just one company to harness the advantages of pierce fastening; having specified more than 70 examples of Profil fasteners in the production of its new MINI.

According to Body Engineering Design Leader, lan Hill: “Increased automation of assembly methods is one of the main reasons we chose Profil for so many applications on the vehicle”.

“Following an intensive assessment session with Profil engineers, we identified several areas that would be ideally suited to pierce fastening methods. These ranged from simple brackets on components such as the fusebox and foot rests, through to `safety-critical' areas including the steering column, bumper and sub- frame mountings.”

It was clear that the Profil system would not only meet our required performance criteria, but that substantial cost, productivity and quality benefits could also be achieved if fasteners were installed as part of each pressing's manufacturing process. The use of purpose-designed automatic feed units and the inclusion of setting dies within the progression tooling has enabled this approach to be adopted. As a result, new parts – complete with installed fasteners – are now produced with every stroke of the press.

“This represents setting rates of more than 100 fasteners per minute – at least an order of magnitude faster than equivalent rivet nut or welded alternatives”, notes Hill.

The consistency and integrity of pierce fastening are also inherently greater than for equivalent welded fixings, which are prone to variations in the base material, surface contamination and operator skill levels. A further benefit of in-press installation is that parts simply can not be produced without the fasteners in place. With manual operations, there is always the risk of individual nuts or studs being omitted, which would cause serious disruption during final assembly.

As a result, M6 and M8 Profil studs and nuts are now installed on the MINI'S fuel tank reinforcing rings, as well as on reinforcers in areas such as the bonnet hinge, door mirrors and handbrake. In addition, M8 RND nuts are employed on the steering column mounting bracket, and a further 6 off M8 studs secure the vehicle's front bumper assembly. Profil fasteners are also specified for the dashboard cross-beam mounting, while the heaviest duty pierce nut variants – incorporating large reinforcing flanges – are reserved for the vehicle's sub-frame anchorage points.

For further information, please contact: Adrian Ellis, Profil UK. Tel: 01530 276515.