#4 | 2020
SYN] Magazin
10/21

Pre-assembly of electric vehicle batteries: no compromises on productivity or safety with the new insulated sockets from Atlas Copco Tools

Whether we are talking about electric scooters, buses or cars, the future of mobility is electric. Increasing awareness of the need for a more sustainable, more environmentally compatible future is forcing especially the automotive industry to break new ground..

The figures speak for themselves: the official new vehicle registration statistics for Germany in 2019 indicate a growth rate of 75.5 percent (and a share of 1.8 percent) for electric vehicles. In the case of cars with hybrid drive systems, the growth rate is 83.7 percent (with a share of 6.6 percent)1 and the upward trend continues.



However, as the demand for electric vehicles grows, so do the challenges. The manufacturing processes for electric vehicles are different from those involved in the production of conventional internal combustion models. The heart of the electric car, the battery, is not only the most expensive individual component. Its assembly is a complex, safety-critical process as employees have to work on live components.  

Trend with unexpected consequences

However, carmakers will need to rethink in the future, especially as a result of the fleet carbon dioxide emission limits set by the EU, which become binding this year. Fines for non-compliance will be payable from 2021 onwards. 2 

Manufacturers need suitable tools to ensure the safe assembly of electric vehicle batteries. Atlas Copco Tools can offer these tools in the form of its new range of high-quality isolated sockets designed especially for the isolation of tightening tools from live joints.


An electric shock may have different effects on the human body depending on the severity, current flow path and duration. These effects range from slight cramps via breathlessness to cardiac arrhythmia. The magazine arbeit & gesundheit reports that currents from about 50 mA upwards can already cause palpitations and lead to a risk of cardiac arrest. Higher currents can even cause internal burns.3

In order to prevent such accidents at work, which may have disastrous consequences, companies have personnel with special electrical training or trained electricians who ensure that all equipment is regularly tested in accordance with DGUV, Section 2 (1), confirmed to be in good condition and that appropriate precautions are taken in connection with the relevant work procedures.

Fatal accidents caused by extremely high currents, sudden arcing or exploding batteries

However, manufacturers will be confronted by entirely new challenges when they produce electric vehicles in the future. In the case of an electric car, the fuel tank of a conventional car corresponds to a highly advanced lithium-ion battery with above-average energy density. The fact that the batteries are preassembled manually in production is especially critical. Both the battery cells and the modules are already charged and battery voltage levels between several hundred and 1,000 V DC need to be taken into consideration.

For people working on electric vehicle batteries and for the tools used, this means that special procedures and safety precautions are indispensable. As one of the leading manufacturers of tightening and assembly tools which are also used in the automotive industry, Atlas Copco Tools has been working intensively for some time on the topic of e-mobility and its effects on future production and tightening processes. On the basis of comprehensive production tests with our tools, three possible risk areas and accident scenarios connected with the pre-assembly of electric vehicle batteries have been identified. These are outlined below. 


Scenario 1: Direct contact with live components

The operator makes direct contact with live components. If properly insulated tools and equipment are not used, voltages of 120 V DC upwards may result in extremely severe injury and possibly death.

 


Scenario 2: Short-circuit of live components with non-insulated tools and equipment

The second risk is posed by direct shorting of the battery cells; in other words, contact is established between live components via non-insulated tools. Such short-circuits may result in arcing, gassing, fire and explosions. These pose a tremendous risk for the operator as well as for the materials and equipment used.

 


Scenario 3:  Short-circuiting of battery modules with grounded tools

A third risk is the short-circuiting of live components with grounded tools. If at least two grounded tools are used at the same time, contact with two battery poles may lead to a short-circuit. The risks involved are the same as those described for the first two scenarios above.




The scenarios described make one thing especially clear: work on live battery connections calls for special, intensive training of operators, adapted assembly processes and, especially, the use of special tools to minimize the risk of injury.It was precisely because of these problems that Atlas Copco decided to develop a quality product with the highest possible safety levels. The results are high-quality, sturdy isolated sockets and quick change adapters as well as insulating covers for electric tools that eliminate virtually all voltage levels and offer the maximum possible protection for assembly personnel. 

Breaking new ground in pre-assembly thanks to the new isolated sockets from Atlas Copco Tools

Everything started with the question of what would be the best way to interrupt the conductivity of metal tools in order to avoid the accident scenarios described above as effectively as possible. At the Atlas Copco competence center, a team of specialists started by developing the solution of insulating tool covers.

The top priority is user safety, which can only be guaranteed if the tools are appropriately protected. The well-thought-out design of the insulating covers consists of a non-conductive plastic and a two-part shell structure that can be simply clipped to the electric tool. With an additional rubber ring and a front cap, tools used in the assembly process are effectively insulated and protected. This way, short-circuits caused by accidental contact between the metal angle head and live components can be entirely avoided.



In the course of the development of the isolation tool covers, it became clear that a holistic solution would also call for special isolation of the sockets. In order to prevent direct contact with live components and short circuits with grounded tools and batteries (see scenarios 1 and 3), Atlas Copco Tools therefore developed two further product innovations: isolated sockets and quick change adapters. Both solutions provide isolation both in the axial and in the radial direction, ensuring maximum process and user safety.


Ground-breaking (patented) insulated tightening systems 


A further special feature of our new insulating tool portfolio is the unique modular principle for which Atlas Copco has already applied for patents. The new quick change adapters (QCAs) are compatible with the tried and tested Atlas Copco ROTACTION range of safety sockets with plastic sleeves, which are insulated in the radial direction. The insulated quick change adapters also provide axial isolation. This way, the existing ROTACTION portfolio can simply be expanded by adding the new isolated socket wrenches from the Saltus brand without having to purchase costly new products or to train operators in the use of such new products.

The comprehensive ROTACTION product range provides a unique variety. Thanks to different ROTACTION sockets, ROTACTION bits and ROTACTION extensions, several hundred different combinations are possible. A further advantage is the fact that the series is part of our standard product range, which is readily available from stock.



Tested and certified

Even though a single applicable standard for isolated sockets is not yet available, the applicable sections of DIN EN IEC 60900:2018 and ASTM F1505 were investigated and various tests were identified to ensure the mechanical strength and electric isolating properties of the sockets. For example, the dielectric strength test was carried out and confirmed both by VDE (Verband der Elektrotechnik Elektronik Informationstechnik e.V.) and by the Intertek laboratory. 

The successful completion of the VDE tests means that we are allowed to use the double triangle symbol in accordance with DIN EN IEC 60900:2018 on our isolated tools.



Intensive testing was also carried out internally. These tests included endurance tests and indentation tests as well as tests to investigate the combustion behavior of the plastics used. 

Doubly safe when working on live systems

Thanks to the specially processed plastic core, these tools offer almost complete safety for the first time. The isolated sockets based on the ROTACTION concept have a 3/8”rectangular drive and are available with the usual hexagonal wrench sizes. Thanks to the additional use of the isolated quick change adapters it is also possible to adapt the existing ROTACTION sockets, which are already insulated in the radial direction.

Dielectric tests of the nonconductive plastic used for electrical insulation were carried out in the axial and radial direction at 10,000 V (high-voltage tests).

Ground-breaking insulated tightening systems

With its portfolio of isolated sockets, quick change adapters and insulating tool covers, Atlas Copco Tools offers a unique complete solution focusing on the highest possible safety levels for the tightening of live components. This system is being continuously developed. For example, a further patent application has been made for the insulating tool covers.





Kraftfahrt-Bundesamt. (n.d.). Jahresbilanz - Neuzulassungen Zahlen des Jahres 2019 im Überblick. Retrieved 6 August 2020, from https://www.kba.de/DE/Statistik/Fahrzeuge/Neuzulassungen/jahresbilanz/jahresbilanz_inhalt.html?nn=2594996
ADAC. (2020, June 15). Elektroautos 2020: Das sind die Neuen. Retrieved 6 August 2020, from  https://www.adac.de/rund-ums-fahrzeug/elektromobilitaet/kaufen/neue-elektroautos
3 Unsichtbare Gefahr. (2018). arbeit & gesundheit, (02), 24. accessed from https://aug.dguv.de/epaper/02-18/#24