Application Technology

Climate protection is becoming increasingly important. When it comes to cutting carbon dioxide output, particular attention is directed to manufacturing industries – especially the automotive industry. Here, Annedore Bose-Munde, qualified engineer and business and technical journalist, looks at how fastener manufacturer Arnold Group is playing its part with sustainability in the fastener industry.

When we look at global developments in the automotive industry it is clear that new cars and vans in Europe manufactured over the years have become progressively heavier – from an average 1,268kg in 2000, rising to 1,360kg in 2010, and to 1,420kg by 2020. With the development of more hybrid and electric vehicles, this trend will increase. The weight of the battery alone means that an electric vehicle weighs on average 300kg more than a vehicle with a conventional engine.

However, by optimising fuel consumption and discovering new and innovative drive concepts, it has been possible to achieve a significant reduction in CO₂ emissions – from around 175g CO₂/km in 2000, to 140g CO₂/km in 2010, and 95g CO₂/km by 2020. This trend needs to continue over the next few years if we are to achieve climate protection targets in the future.

Fastener manufacturers must look at sustainability

One thing of which we can be certain is that to keep the carbon footprint as low as possible, everyone must pull together to develop and implement strategies aimed at consistently protecting the climate. Sustainability is of extreme importance for German-based fastener manufacturer Arnold Group, as it is one of five strategic approaches employed by the company – along with eMobility, internationalisation, lightweight engineering and digitisation.

Climate protection and the sustainable use of resources have long been firmly founded principles for the company, well before the increasingly forceful climate change debates of today. When Arnold was founded back in 1898, its first factory was accommodated inside an existing mill meaning the machines were powered by renewable power – water.

Over the decades of its activities, the sustainability theme continued to weave through Arnold’s corporate activities, including a reduction of CO₂ emissions stated in the annual sustainability reports produced since 2014. Since 2016 Arnold has also publicly affirmed its sustainable corporate leadership with its ‘Blue Fastening System’ claim. In 2022 this development will continue with the signing of the UN Global Compact Initiative.

Looking at emissions throughout the entire supply chain

Arnold values the fact that sustainability and carbon neutrality is considered throughout the entire supply chain. An individual footprint account is drawn up for every product throughout the entire value-added chain. Emissions from each section of the supply chain are added up. This means that companies downstream of the supply chain take on the totalled emissions from its own suppliers and then pass them on, with its own CO₂ emissions added on, to its customers. This is an obligation placed on every company within the supply chain, to take responsibility, not only for its own processes and the power it uses, but also for previous and subsequent processes.

This is why Arnold has set-up the ACO₂-Save initiative. With this initiative, customers and users are actively supported to reduce CO₂ emissions by designing and using fasteners and cold formed parts sustainably. A carbon calculation takes place as early as the development process. Using its own CO₂ calculator – developed in-house – Arnold is able to determine the Product Carbon Footprint for the part the customer is enquiring about, then can work together to improve it. The aim here is that at the end of the development process, the product is technically of high-quality, and optimised with regard to costs and its CO₂ footprint.

ACO₂-Save provides many options for CO₂ savings

To curb CO₂ emissions as early as the development stage, for example by avoiding making unnecessary samples and prototypes, Arnold’s developers make use of digital forecasting tools such as FEM analysis and its own prediction program, developed in-house. This greatly reduces the number of feasible variants thus saving time, money and CO₂.

However, the greatest savings are made by using innovative fastening and cold forming technologies. For example, working with its customers, Arnold analyses options for changing the parts production technology – including whether parts that until now had been machined, might be more efficiently produced as cold formed parts. It is also possible to check whether any existing threaded screws could be replaced by thread forming screws, completely doing away with the need for thread cutting tools and the emissions they cause.

A further option is to reduce size by using innovative fasteners, for example by replacing an M5 screw with an M4. And finally, innovative fastening systems help to reduce weight – especially when it comes to joining multi-material mixes – and that ultimately means a reduction in the vehicle’s overall emissions.

To illustrate exactly how this ACO₂-Save initiative is working, let us look at a specific example. The task was to subject a special screw made of aluminium to a review with regard to technology, cost and CO₂ emission. A Conform Next screw was developed as an alternative. Due to its engineered design, it proved suitable for use in components with bigger diameters, longer components, more complex geometries, and heavier weights, i.e heavier components. The volume of the part used previously was 8,733mm³, each item weighed 23.5g, and was machined in the traditional way. A turned part blank was used on the production line and the volume of that was 25,830mm³, weighing in at 69.2g each item.

Arnold’s developers carried out an ACO₂-Save analysis and changed the part to a formed part on the Conform range. Following the improvement the volume of the formed blank was 9,135mm³ and each one weighed 24.82g. In other words, the forming process requires much less material input since there is very little wastage during the production process.

Besides a considerable improvement in costs created by lower materials requirements for the cold forming process, this also has a considerable effect on the product carbon footprint for this special screw. By reducing the working weight, creating less waste, and thus making the production process more efficient, it was possible to reduce all the CO₂ emissions created by this screw by 45%.

This single example already goes to show that there is considerable potential for reducing the Product Carbon Footprint with Arnold’s ACO₂-Save initiative. Correspondingly, it also means that a pragmatic and individual analysis of other possible approaches to making changes, with regard to fastening solutions, must as far as possible be handled responsibly in corporate and societal terms.