Electrical vehicle technology: build lighter, build stronger

4 mins read

EJOT UK explains its product offering bringing strength and lightweight benefits to the electric vehicle market.

Micro-screws in a radar assembly
Micro-screws in a radar assembly

Governments around the world have been driving the need for carbon dioxide reduction for many years, culminating in global shift towards commercial electrification.

EJOT’s dominant market for industrial engineering thread forming screws is historically automotive, largely driven by its product portfolio based on a foundation of parts rationalisation – reducing the number of fastening products in assemblies – allied with higher joint strength performance. In Germany, the firm’s development teams have been working with vehicle manufacturers and academic institutions as part of the on-going process towards electrification.

“Fastener development, product modifications and new joining systems allied to differing vehicle construction materials and methods have all evolved during this period and they are part of the electrification revolution we are already seeing,” says EJOT’s UK sales manager for industrial fastening solutions Steve Wynn.

As he explains, the obvious mechanical difference between combustion driven vehicles and electric vehicles (EVs) is that the latter has no conventional powertrain, which is instead replaced with a motor and electric control unit (ECU).

“We are seeing a shift in product deployment across the range,” he says. “For example, the escalation in the need for printed microcircuit boards – usually set into a light aluminium casting – is the domain of EJOT’s micro screw range. These thread-forming screws provide the performance at a miniaturised level that designers would normally expect to achieve with much larger screws, as an alternative to soldering, gluing, clipping, or welding.”

Meanwhile, EJOT’s ALtracs Plus thread forming screws offer great potential for EV applications as they act as heat sinks – removing heat that is dispersing throughout the system – whilst providing a strong and vibration resistant join, Wynn continues.

“Electrification has created a shift in the prevalence of products such as micro screws, which are deployed already to a lesser extent in combustion vehicles,” he adds. “But in addition to providing the benefits outlined above, the demand for eConnectivity within the vehicle – the ‘infotainments’ that are prioritised by a new generation of vehicle buyer – is also increasing the requirement for these types of joining solutions.”

Lighter & stronger products

Engineering for the EV sector is largely dominated by the need to build lighter and stronger parts, and in turn this has led to the advancement of many new engineering materials. Carbon fibre is one such material, sought after for its light weight, versatility, and high strength.

EJOT’s product range has responded accordingly with the development of products such as the EVO PT self-tapping thread-forming screw. The latest generation of the PT which revolutionised fastening into thermoplastics back in the 1970s, the EVO PT has the benefit of an optimised locating point and depth independent installation torque that enables a uniform tightening torque in production at different screw lengths.

“Another technology with great EV potential – already used by the automotive sector for conventional vehicles – is EJOWELD,” says Wynn. “This is an example of how EJOT has worked to develop joining systems outside of thread forming technology.”

EJOWELD is a friction weld system that was developed in conjunction with a premium German vehicle manufacturer who sought to take weight out of traditional vehicle design. The solution was to deploy high strength boron steel as the core structure for body-in-white structures, a move that offered extreme strength benefits in a much thinner material than those traditionally used. As such, the solution demanded a new approach to joining secondary allots to the main vehicle body, culminating in the development of EJOWELD.

“Other EJOT systems outside of the traditional thread forming portfolio can be found where lightweight foam and composite materials are being utilised for the same kind of ‘weight to strength’ ratio prerequisites being engineered into EV structures,” says the UK sales manager. “The TSSD is one such fastening system – this thermal adhesive bonding boss provides a secure boss for the EJOT DELTA PT screw or a direct fastening element.”

Innovative EV applications

Many of EJOT’s work with OEMs on specific fastening assemblies are subject to NDAs. However, he explains how one major German vehicle manufacturer uses the company’s fasteners for the complete power electronics assembly within its electric and hybrid vehicles.

“This includes the plugs and connections, circuit board, elec­tric contacts, seal cover for the internal cooling unit and housing cover,” he reveals.

In terms of specific applications where EJOT’s fastening products have been deployed on EVs, he gives the ALtracs Plus as an example. One vehicle manufacturer uses this to secure the PCB onto a heat sink so the screw assists with the heat transfer, while another major German manufacturer uses it for the connector housing for DC adaptors as well as the HV/LV filter in the vehi­cle’s power electronics and WR and PWRDC/DC units. It is also used alongside the EJOT Delta PT screw for fastening the battery back and WR DC/DC unit by another automotive manufacturer.

Additionally, the Delta PT has been deployed within several battery related applications for a prestige German car manufacturer which uses the screw for fastening the lithium battery, the onboard charger circuit board securement and as a casing fastening for the battery.

As Wynn points out, there are notable differences in the manu­facturing requirements of EVs and combustion engine vehicles.

“It was initially thought that new materials required for EV construction would make adhesive solutions a more attractive, dominant approach to fastening and they would gain the market share,” he says. “However, while this has partially become true, mechanical fastenings are still a strongly preferred option, in part due to the hurdles of curing times and fumes from associated with using adhesives.”

The key challenge, he adds, continues to be designing mechanical joining systems for thinner and more lightweight materials, particularly when parts that are lightweighted also become more flexible in many cases.

“This highlights the necessity to work years in advance of new vehicle assemblies to ensure the joining technology is tested and available for when the need arises,” he explains.

Opportunities ahead

When asked what opportunities lie ahead for EJOT in the EV market, Wynn highlights the need for charging points to match demand for EVs as an obvious focus: “EJOT’s EVO PT screws are already being deployed in this area – up to 50 fastening elements are used in home wall charging stations and so the EVO PT screw’s direct fastening capability in plastics has many advantages,” he says. “It is supported by EVO CALC, a prognosis programme that can be used in the development phase for advance computation of the screw joints saving time and costs.”

With more EVs becoming commonplace on our roads, the need to charge with speed, economically and in multiple loca­tions is an area the company is keen to be involved with.

“The need to design strength using lightweight materials is here to stay,” the UK sales manager continues. “It therefore follows that engineering materials such as carbon fibre mould­ings may present cost issues now, but as demand increases then costs will fall.”

Additionally, environmental and sustainability concerns go beyond vehicle mechanics alone. “Whilst vehicle manufactur­ers are ticking boxes to build lighter and stronger, the emer­gence of recycled plastics as a modern engineering material is one our design teams are already involved with, initially with the need to determine fastening performance in comparison to original material compositions,” he adds.

This article was originally published on the EJOT website: https://www.ejot.co.uk/Electric_Vehicle_Technology