How are innovative fastener systems enabling e-mobility designers to develop vehicles with greater customer appeal?
According to the EY Mobility Consumer Index in 2022, the key inhibitors of electric vehicle (EV) purchase after higher upfront cost still relate to how far the vehicle will drive on a single charge, and the availability of the facilities to re-charge.
Whilst the index noted that fewer consumers have concerns in these areas compared with previous years, it is clear that many buyers and drivers remain wary about moving away from the long ranges they have become accustomed to with traditional internal combustion engine (ICE) vehicles. Hence, it is imperative for every EV manufacturer to pursue a parallel strategy involving continuous improvement of the battery performance and reduction in vehicle weight. Without achieving the latter, advancements to increase vehicle range will be constrained to a point where mass adoption may still be difficult to achieve.
One of the facilitators for the EV sector’s growth, therefore, is the ability to use more innovative lightweight materials without compromising the strength, durability or safety of the vehicle. Key to this are technologies which securely fasten materials such as honeycomb structures, PIR, EPP foams and thin sheet metals or composites.
And it is here where several fastening systems developed by Ejot are being deployed, including one system which was developed with Audi back in 2014. Called the TSSD (Thermischer Stoff-Schluss-Dom), which translates into English as ‘thermal adhesive bonding boss’, this 9mm diameter fibreglass reinforced thermoplastic polymer boss found its first live application came when designers needed a way to create a fast high-strength joint in a parcel shelf manufactured from a PUR fibreglass and paper honeycomb composite.
The TSSD is a joining process which involves installing the plastic boss with a certain rotational speed, which generates heat to create a bond, and axial load. Once inserted, the TSSD boss can then be used in conjunction with either the Ejot Delta PT or Evo PT screw. It was co-developed with a partnering OEM of installation equipment in Germany, but it has since evolved in the UK to incorporate different drive options, including a full automated system and handheld DC tools. Several variants have been developed too, including a boss with a ball-headed ‘snap-on’ connector moulded in and a male and female hinged connection.
Fast-forward to 2023 and TSSD is now playing a key role in EV design, as one application for a premium British vehicle manufacturer demonstrates. In the development of a new model, which includes EV versions within the range, Ejot was approached by the design team to explore the potential of using TSSD to overcome a similar challenge to that which Audi faced in 2014.
In this latest application, the vehicle manufacturer will used closed cell foam with fabric stiffener for the parcel shelf, into which the TSSD boss will be inserted to accommodate the parcel shelf hinge pin. The resulting fastening element enables this manufacturer to utilise lightweight materials to reduce the overall vehicle weight, whilst at the same time delivering a secure joint that reflects the premium quality throughout the vehicle.
Dan Lunn is an Application Engineer UK South at Ejot