Rethink: thinking about the end right from the start
Audi is working to align its use of resources along the value chain more closely with circular economy principles. To achieve this, relevant requirements are to be increasingly taken into account in the early stages of product development.
A linear economic model is characterized by the extraction of raw materials, their one-time use and subsequent disposal at the end of a product’s life cycle.In the circular economy, on the other hand, components and materials are intended to remain in use for as long as possible and, wherever technically feasible and ecologically and economically viable, to be returned to the material cycle. Audi considers the circular economy across the action areas of Product, Business and Partnering. As part of this approach, the company assesses, among other things, the use of secondary materials and post-consumer materials for selected vehicle projects and components.
Post-consumer 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.
A key challenge associated with post-consumer recycled materials is processing and using them in a way that enables them to meet the specific technical and quality requirements for vehicle components. The goal is to keep materials in the loop without any loss of quality and to avoid downcycling.
The so-called rethink principle is already applied in the early phase of product development:with “Design for Circularity.” Components that are developed according to this principle already consider later recyclability as early as their design phase. Aspects such as suitability for dismantling, repairability, maintainability and recyclability are considered from the outset for components developed in this way. “It’s about much more than ‘just’ design,” says Christine Maier, Designer in Materiality Experience 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. Together they work on developing components and materials in such a way that they can be reused or recycled to the extent that is technically feasible and ecologically and economically viable.
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 upholstery. Few other components 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 upholstery. To make the seat upholstery, the surface of the seat is bonded with a backlining. The joining of the different layers is what gives the seat upholstery 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 upholstery 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 effects as far as possible, products can be designed during the development stage in a way that allows material combinations to be separated more easily later on. Another approach is the use of monomaterials, where the different material groups do not need to be separated.
Using the seat upholstery as an example, Audi demonstrates a component-specific approach to the use of single-material solutions: 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 monomaterial design, offcuts that arise during production of the seat upholstery can be recycled under defined conditions. The offcuts are shredded, melted down and can be processed into new yarn. After successful quality testing, this yarn serves as the basis for new seat upholstery. At the end of their product life, seat upholstery of this type can be fed back into the recycling loop. The raw materials used in the seat upholstery can be recycled mechanically (with low energy consumption) three to five times instead of just once as is the case with conventional upholstery.
Günther Ernst from Technical Development adds: “We did a rough estimate based on an internal model calculation. Audi could save around 160,000 square meters of textile material per model and year by recycling monomaterial offcuts from the production of seat upholstery. That translates to some nine metric tons of material per year and model. ”
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
As with conventional seat upholstery, the newly developed monomaterial upholstery 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 Materials Engineering 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 ensure that the textiles used for Audi comply with defined requirements for quality and approval. 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 upholstery, such as strength, elasticity, lightfastness and wear.” What are the requirements for the quality of the newly developed monomaterial seat upholstery? “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 upholstery 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 upholstery and the seat cushion will also be made of polyester in the future.
Trim elements in the interior: single-origin and premium
Components made of monomaterials are generally easier to recycle. “However, these monomaterial components, 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 monomaterial components with a premium look and feel and has filed for patent for the solution: The new interior trim elements as well as classic components have a multilayer structure. However, all layers (carrier, soft component and surface) come from a single material family and are therefore of single origin. “Components produced in this way can be reused as raw materials. They act as the source material for selected components in the vehicle interior with the same grading level. ”
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 components. 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 resource-efficient and circular-oriented component design, including best practices. It describes how to use fewer resources in components and how the materials incorporated in them can be reused in production. Detailed material-specific guidelines are intended to support developers in selecting 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. A guideline and a web-based training program were created in collaboration with polymer experts on the recycling-friendly product development of plastic components. This guideline is also binding for suppliers. Further documentation for other materials is in progress.
In addition, Audi is developing a methodology that enables selected circularity criteria for components to be assessed in a structured manner. The insights gained from this assessment may in the future be incorporated into development decisions for selected components in new vehicle projects.