Rethink: thinking about the end right from the start
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In the linear economic model, raw materials are used once and then disposed of when the product reaches its end of life. In the circular economy, on the other hand, parts and materials are reused through maintenance and repair, remanufacturing and refurbishment or recycling, for example. In its approach to the circular economy, Audi is guided by the principles of Reduce, Reuse and Recycle and is aiming to steadily increase the proportion of secondary material used in new vehicles. Audi wants to intensify use of post-consumer material with the next generation of electric cars based on the Scalable Systems Platform (SSP). The recycled material comes largely from products that have already been used by end consumers. Due to the necessary dismantling and sorting of the material mix, the recycling of such materials is much more challenging than in the case of post-industrial materials, which in turn come from industrial production waste, such as offcuts for example. Post-industrial materials are generally sorted and collected separately, which means that their material composition is known. As a result, they can be processed relatively easily into post-industrial recycled materials. Such recycled materials are therefore generally of a higher and more consistent quality. This makes Audi’s plan to focus on post-consumer recycled materials and at the same time maintain the quality of the original material (avoiding downcycling) all the more ambitious.
The Rethink principle starts significantly earlier, namely in the early phase of product development – with “Design for Circularity.” Parts that are developed according to this principle already consider later recyclability as early as their design phase. Aspects such as suitability for dismantling, repair, maintenance and recycling are taken into account from the outset for parts developed in this way. “It’s about much more than ‘just’ design,” says Christine Maier, Designer in Color & Trim at AUDI AG. “We’re changing the approach to how we develop vehicles. Our starting point is the end: before a product begins its life cycle we think about how it will end it and how we can design it in line with the principles of the circular economy.”
To achieve this goal, experts from all divisions of the company come together in interdisciplinary teams, including members from Design, Technical Development, Procurement or Corporate Quality. They are tasked with ensuring that parts and materials can be reused and recycled as often as possible.
Thinking about circularity as early as possible: in the area of seat upholstery, for example.
How do these interdisciplinary teams collaborate in practice? It helps here to cast a glance at a part that no car can do without: the seat cover. Few other parts in a vehicle’s interior are subjected to such wear and tear and, at the same time, are of such importance for the comfort of passengers.
A car seat is made up of the supporting structure, the seat cushion and the seat cover. To make the seat cover, the surface of the seat is bonded with a backlining. The joining of the different layers is what gives the seat cover its stability. This helps it keep its shape for a long time. Up to now, it has been standard practice in the automotive industry for the seat cover to be composed of multiple material families. The fabric of the seat surface generally consists of polyester and is bonded with a backlining, usually polyurethane (PUR) foam.
Günther Ernst is responsible for material development of textiles in the Technical Development department dealing with the interior trim: “The problem is that two different material groups are used to join the layers. And it is difficult to separate these from one another for later recycling when the seat reaches its end of life after two or three decades, assuming normal wear and tear. The sorting of the material groups by type is critical however for recycling.”
Materials are of a single origin when they come from the same material family. It is much more complex to recycle composite materials as they are difficult to separate from each other in the recycling process. Impurities that arise due to the mixing of different materials have a negative impact on the recycling process and can ultimately lead to downcycling. In this case, the end product of the recycling would be of lower quality compared with the original product. To avoid such a situation, products should therefore be designed in a way that allows material combinations to be separated as easily as possible. Alternatively, monomaterials should be used that do not need to be separated in the first place.
It is clear from the example of seat covers that Audi plans to use single-origin parts in its vehicles in the future. A newly developed Audi seat cover comprises one material family (monomaterial). The seat surface, the adhesive and the backlining (nonwoven) are all made of polyester. In addition, the seat surface and the backlining already contain a high proportion of recycled polyester. Thanks to the nature of the monomaterial, offcuts that arise during production of the seat cover can be recycled directly. The offcuts are shredded, melted down and can be processed into new yarn, which acts as the basis for the new seat cover. At the end of its product life, seat covers of this type can be fed back into the recycling loop. The raw materials contained in the seat cover can be recycled three to five times instead of just once as is the case with conventional covers.
Günther Ernst from Technical Development adds: “We did a rough estimate. Audi could save around 160,000 square meters of textile material per model and year by recycling single-origin offcuts from the production of seat covers. That translates to some nine metric tons of material per year and model. And while it could be argued that ‘A large textile supplier produces this amount in about one day’, it’s a start. The true potential becomes clear if we imagine what would happen if we were to extend the concept to other parts.”
Christine Maier: “As a car manufacturer, we – and that includes me as a designer – have a responsibility that goes beyond the pure aesthetics. It goes without saying that seats in the future have to at least look as good and be as comfortable as their traditional predecessors. But they must also be easier to recycle.”
The circular system and quality
The circular system and quality
As with conventional seat covers, the newly developed monomaterial cover must also fulfill criteria such as cost efficiency, weight and quality. When it comes to quality, this is Jürgen Frank’s specialty. He works in Corporate Quality and is responsible for the quality of the textiles in the vehicle interior from the early development phase through to final use in the vehicle. The engineer has been working for 20 years in collaboration with suppliers to guarantee that the textiles used for Audi are of perfect quality. It is only when he approves the material that the supplier can start producing. “There are about 30 factors we use to test the seat covers, such as strength, elasticity, light-fastness and wear.” What are the requirements for the quality of the newly developed single-origin seat cover? “I make no distinction between the quality of recyclable or conventional materials. An Audi seat has to work, regardless of how it was designed. The newly developed seat covers have to perform just as well in the quality tests. We owe this to our customers,” says Jürgen Frank.
The team is working to reduce the material mix of the entire seat even further in future development stages. For example, the joining elements between the seat cover and the seat cushion will also be made of polyester in the future.
Trim elements in the interior: single-origin and premium
Parts made of single-origin materials are generally easier to recycle. “However, these monomaterial parts, such as injection-molded polypropylene parts used in the door panels, have a hard surface and do not always meet our premium standards when it comes to a soft surface experience,” says Kai Schauerte, Value Engineer in Audi Procurement. AUDI AG has now overcome the challenge of producing single-origin parts with a premium look and feel and has filed for patent for the solution. The new interior trim elements as well as classic parts have a multilayer structure. However, all layers (carrier, soft component and surface) come from a single material family and are therefore of single origin. “Parts produced in this way can be reused as raw materials. They act as the source material for parts in the vehicle interior with the same grading level. A new phenomenon in the automotive industry.” Moreover, this type of production process should also enable a choice of different surfaces (e.g. textiles or synthetic leather) so that customers can continue to be offered the usual high-quality range when it comes to the design of the vehicle interior.
Designing the future, not going around in circles
“Design for Circularity” challenges the status quo and requires a rethink of the way products are developed and produced. Christine Maier, Günther Ernst, Jürgen Frank and Kai Schauerte want to maximize the potential of the Rethink principle in the development and production of Audi parts. To do this, they need fellow collaborators who know how they can contribute optimally and what plan they need to follow. Guidelines and web-based training programs provide support to development departments in the company as well as knowledge about “Design for Circularity.”
The Audi design department has already developed an internal handbook on sustainable design including best practices. It describes how to use fewer resources in parts, how the installed materials can be reused for production and how CO₂ emissions can be reduced during the manufacturing process. Detailed material-specific guidelines support developers in selecting more recycling-friendly materials or joining techniques – for example through the use of monomaterials, composite materials that can be separated easily or non-destructive joining techniques that simplify dismantling. Another guideline and a web-based training program were created in collaboration with polymer experts on the recycling-friendly product development of plastic parts. This guideline is also binding for suppliers. Further documentation for other materials is in progress.
Moreover, the plan is to make it possible to quantify and compare the recyclability of parts and vehicles in the future. Thanks to this methodology, Audi could then optimize the recyclability of new vehicles and the parts used in them in a second step.
