Building a secure future for electric vehicles (EVs)

By Steve Wynn, UK Sales Manager for Industrial Fastening Solutions at EJOT UK.

Fastening technology developed by EJOT has been evolving to satisfy the key design requirements of fuel efficient vehicles for decades, facilitating much higher MPG and lower CO2 emissions in petrol, diesel and hybrid engines.

Now, as battery technology has advanced to a point where this type of power unit is becoming dominant in new vehicle manufacturing, many established fasteners are already well placed to facilitate the production of battery electric vehicles (BEVs).

What is new in many cases, however, is their application. Many design engineers are finding new purpose for fasteners that were always designed to be capable of facilitating the joining of innovative materials, particularly the lightweight plastics, composites and think sheet metals which are so important in EVs.

But as futuristic and revolutionary as many EVs or hybrid vehicles look, it is important to recognise that the construction methodology and assembly approaches they benefit from are largely the result of an evolution which EJOT has been supporting since the 1970s.

Fasteners perfectly suited to automotive innovation

EJOT’s industrial engineering thread forming screws have historically found their biggest market in automotive because of the features and benefits common in all EJOT fastening products. These are principally to do with parts rationalisation, with the aim of the fastener to reduce the numbers of fastening products needed in an assembly, allied to delivering higher joint strength performance.

Whilst these factors have benefited internal combustion engine (ICE) vehicle design for decades, we are seeing EV manufacturers deploying these proven fastening solutions in new ways to different types of assemblies throughout the vehicle.

One example of this is relates to the motor and electronic control unit (ECU) which EVs use instead of a conventional powertrain. As the ‘command centre’ of the vehicle, this requires fasteners that will enable printed microcircuit boards to be secured into a light aluminium casting. It is an application that can be comfortably accommodated by EJOT’s micro screw range.

This is by no means a new product range. In fact, these thread-forming screws have been available for at least 25 years and were originally used on Ericsson and Nokia mobile phones to provide performance at a miniaturised level that designers would normally expect to achieve with much larger screws. This performance gives designers an effective alternative to soldering, gluing, clipping or welding.

But it is not just the micro screws that are finding new purpose in EV applications. Other established EJOT fastening technology is being used in the connector housing for DC adaptors, the HV/LV filter in the power electronics and for both the WR and PWR – DC/DC Units. One major German vehicle manufacturer is using the EJOT ALtracs Plus, a self-tapping screw for light metals, for all these applications, while another is using the EJOT Delta PT, a screw for direct use with thermoplastics, for fastening the battery pack and WR DC/DC unit.

The Delta PT screw is proving particularly useful for battery packs, which have been a particular application focus over recent years – for obvious reasons. One example is with a prestige car manufacturer which specifies this screw for several battery-related applications, including for fastening the lithium battery, the onboard charger circuit board securement and as a casing fastening for the battery.

Maximising EV range through weight reduction

Advances in how the vehicle structure and body is built have had to run in parallel with the development of the power technology required in order to make EVs a realistic alternative to combustion engine vehicles. The key reason for this is to reduce weight so the vehicle range is maximised.

ICE vehicle fuel efficiency has, of course, been a priority for several decades, driven by climate change, which has resulted in government policies around the world principally to reduce CO2 emissions. The development of electrification commercially has been part of that drive and in Germany, where the EJOT Group is based, our development teams have been working closely with vehicle manufacturers and academic institutions as part of that process for many years.

And today we are realising the benefits of that long term process. Fastener development, product modifications and new joining systems allied to differing vehicle construction materials and methods have all evolved in recent decades and they are part of the electrification ‘revolution’ we are already seeing.

Supporting the goal to ‘build lighter, build stronger’

Key to everything in the EV sector is the ‘build lighter, build stronger’ objective, which has led to the advancement of many new engineering materials such as carbon fibre. This is light, versatile yet high in strength.

The potential of these new materials, however, can only be unlocked if similarly advanced joining technology and fastening solutions are readily available. This is why EJOT has responded with the development of products such as EVO PT.

The EVO PT’s story is one of evolution with every generation offering something more. This innovative self-tapping thread-forming screw is the latest generation of the PT which transformed the way we fasten into thermoplastics in the 1970s. Amongst its key benefits are an optimised locating point and depth independent installation torque, which enable a uniform tightening torque in production at different screw lengths.

Beyond the thread-former

Another technology with ever increasing potential for use in EVs – and already used by the automotive sector for many ICE vehicles – is EJOWELD. This is one example of how EJOT has worked to develop joining systems outside that of thread forming technology.

The history of EJOWELD is 100% automotive. It is a friction weld system that was developed in conjunction with a premium German vehicle manufacturer who was looking to take weight out of traditional vehicle design. One of the ways it proposed to do this was to deploy high strength boron steel as the core structure for body-in-white structures.

This would offer extreme strength benefits in a much thinner material than those traditionally used, but it demanded a new approach to joining secondary alloys to the main vehicle body. EJOT responded with the development of EJOWELD.

But it is not just the vehicle body where weight reduction is sought. The increased use of light weight foam and composite materials with a good strength-to-weight ratio has also demanded new ways of fastening, and this had led to the development of systems like the EJOT TSSD.

The TSSD is a thermal adhesive bonding boss designed to provide a secure boss for the EJOT DELTA PT screw or a direct fastening element, as well as EJOFORM bespoke cold formed fastening elements. It offers great versatility for designers to consider creative ways of fastening as the virtually unlimited application potential offered by EJOFORM means lightweight materials can be considered in all kinds of assemblies where previously the ‘how do we attach it?’ question was a barrier. This could be for the locking system on doors, the trunk lid or engine covers.

Continuous innovation addresses tomorrow’s challenges

EJOT remains at the forefront of fastening solutions that will enable ever lighter and more efficient EVs through a continuous R&D programme and close partnerships with the designers at many of the world’s major vehicle manufacturers.

And this has always been regarded as a long term, ongoing process, with EJOT required to work years in advance of new vehicle assemblies to ensure the joining technology is tested and available for when the need arises.

Beyond the vehicle, we are also looking at how we can support greater EV use, including in the manufacture of charging points. We are already working with manufacturers to help them scale up to mass production of these units, which can use up to 50 fastening elements in a single unit.

One of the products that is proving effective here is the EVO PT screw, which enables direct fastening capability in plastics and has the benefit of being supported by EVO CALC. This prognosis program can be used in the development phase for advance computation of the screw joints to save time and costs.

Find out more about EJOT’s fastening solutions and technical support for the automotive sector at www.ejot.co.uk.