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Battery systems & e-mobility

Agile joining technology in the battery systems field

The intense debate about whether the combustion engine, which has been successful for decades, the secret favourite ”fuel cell“ or the battery-electric vehicle is the better choice has been steered in one direction after many discussions, political decisions and funding strategies – at least for the time being. And when market-leading OEMs clearly choose a battery strategy, this adds increased dynamics to the market.

It is exciting to see how electromobility is constantly evolving in almost every detail. Hundreds of thousands of engineers and scientists from different faculties worldwide are working to optimise the relevant systems. The battery and its electronic peripheral unit is the detail of electromobility which will be crucial for the ecological and economic suitability of this type of drive. And with range, costs, environmental compatibility and charging convenience, the cost-intensive battery becomes the main criterion for buyers for or against this type of drive.

 

Research by automobile historians sees the birth of the first German electric car as early as 1888, perhaps even the world’s first four-wheeled passenger car. And yet the rapid development of petrol and diesel generator sets replaced electric mobility for the next century.

 

 

A manufacturer of fastening technology solutions undoubtedly also sees the world from the point of view of the automotive drive, but even more from the challenge of changing fastening technology constructions and tasks. In application areas with above-average development dynamics and the field of automotive drive technology, one can certainly see that designs and materials change at high speed. Development times are drastically reduced through the use of digital methods such as computer simulation, additive manufacturing, virtual product development and other tools. In this context, agility in joining technology means being able to develop fast, predictable, material-adapted and economical connection solutions and, where necessary, assembly solutions ready for series production.

 

Many different joining processes are also used in battery and electric drive systems, both detachable and non-detachable. Joining technology here has the purpose of connecting the battery components so that they have continuous-load capability and, where necessary, are able to take on additional functions. And this also and especially when the material combinations consist of two or more, sometimes considerably different materials. Some specific challenges are discussed below using specific application examples.

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EJOT FDS® screw

The first application shows the possibilities of detachable screw connections in the area of the battery box cover. A variant of the EJOT FDS® screw is used here, a flow-drilling fastening element for detachable high-strength sheet metal connections which usually does not require any component preparation, such as pre-drilling or punching. FDS® screws have proven themselves millions of times in body-in-white construction. Due to the increased thread engagement in the formed draught, a highstrength screw joint without any undesirable swarf is created. The problem of the risk of battery fires and short circuits did not first come to the attention of development engineers through press reports about burned-out luxury electric vehicles. This joining technology is a component of the safety concept in this construction.

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The special feature of the battery cover fastening presented here is the pre-assembled embossed aluminium sealing washer, which ensures waterproofing from the head of the cover. Protection of the battery interior from moisture and dirt is ensured and the screws can be loosened for maintenance purposes without any problems. The agile supplier is able to carry out necessary adjustments in the product design and in the process safely and efficiently. Another important criterion of the OEM, the global availability of the joining technology, is guaranteed for this product family by EJOT and the FDS® licensees.

FDS®

EJOWELD® process

Another joining technology, originally designed for bodywork, is the EJOWELD® process, friction welding with a friction element. This process offers the possibility to join composite material with a robot-compatible installation tool without any pre-treatment. The battery frame box in this application example has a base that is made of aluminium for weight reasons. In a multi-stage installation process, the aluminium is penetrated, the surface of the steel material is activated, the friction element as well as the base sheet are plasticised and finally the welding is formed. As a system provider of joining and setting technology, you have to respond flexibly to the customer’s legal and standard-based requirements and also prove yourself in an international environment with appropriate training and maintenance plans.

 

And since the production of the entire battery system is ultimately measured by its CO2 footprint, this technology offers significant advantages over the alternative method of resistance spot welding due to its low energy balance.

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In summary, it can be said that almost all connection and joining technologies can be found in current battery systems. The special requirements on battery technology regarding fire protection, crash safety, watertightness or high-voltage technology, with its strict safety regulations, demand the highest level of safety and performance from the joining technology. Due to the short development times for new battery generations, manufacturers must be able to develop and test resilient products and, where necessary, the appropriate assembly systems for the specified material combinations at short notice and with the greatest flexibility, and make them ready for global series production.

 

 

EJOWELD®

FDS®

EJOWELD®

Battery systems

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FDS®

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Multi material designs

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