The first contribution attempts to provide a state-of-the-art design for these high-value-added end-of-life strategies. The focus today is on end-of-life strategies that maximize the value of products, so-called reuse strategies.
Definitions and Main Characteristics
The focus of this section is on reuse strategies that occur directly after the end-of-use (EoU) of products. They both ensure reuse goals, while the main difference stems from the amount of operations required to make the product reusable again. If the process required to rebuild the product is primarily a cleaning process, it is considered direct reuse.
Otherwise, if the process requires machining and more complex operations, it represents a rework strategy. Among the different end-of-life strategies, direct reuse is said to have the best environmental and economic benefits (European Commission 2008; Arnette et al. Furthermore, both would conserve resources as they could be seen as “a new product to be avoided .” Hatcher et al. 2011) further add that it could be “a combination of new and reused parts”.
The main drawback of both strategies lies in the efficiency in use of the product when it is reused.
Design for Reuse
Indeed, Sundin and Bras (2005) and Zwolinski et al. 2006) detailed product characteristics and process activities taking into account external factors. These guidelines help designers to define product and process parameters in line with the strategy of the company. In that process, gathering the different actors from the early stages would facilitate the integration of the different constraints, whether linked to the product, the process or the business model.
From that point, the design process follows different steps to progress from product idea to product retirement (see Fig.2). Although they follow a reuse strategy at the end of their use, the products to be reused should be considered like any other production in the first place, so that the design stages between the two do not differ much (Gray and Charter2008) . Despite this, the main issue for products to be reused lies in the integration of the required parameters that are designed to ensure the end-of-life strategy.
To be deployed efficiently, they need to be integrated from the early stages of design (Gray and Charter 2008).
Main Guidelines for Design for Direct Reuse and Remanufacturing
Standardize and use common materials, components and fasteners Use modular parts and components, reducing the complexity of Provide legible labels, text and barcodes that do not wear off during the life of the product. Guidelines dedicated to both direct recycling and remanufacturing were collected in a column labeled 'Guidelines for recycling strategies', while those specific to remanufacturing were separated in the column on the right.
Table1 therefore groups characteristics and guidelines that address the process Table2 then collects the various characteristics and guidelines that are related to the product. The reasons are that none of them were identified in the literature or due to the fact that the guideline was closer to another characteristic. However, this seems logical, as the major difference between the two is that remanufacturing implies more remanufacturing before the product can return to the market.
This is noticeable in Tables 1, 2 and 3: all the specific processing guidelines are directly or indirectly related to the steps of the processing process.
Discussion
Limits of Direct Reuse and Remanufacturing Strategies
This is clearly the case today for batteries of electric vehicles that cannot be remanufactured for the simple reason that the technology is not able to restore the initial performance at a reasonable cost (Beverungen et al.2016). Quantity depends on the efficiency of the collection process and the ability of the market to absorb more products. In addition to the economic issue, the environmental issue of waste management can also act as a significant driver of the business.
Let's explain the concept with the example of electric vehicle batteries, which are currently discussed in the literature. Idjis (2015) studied a recycling network for electric vehicle batteries from a “techno-economic, organizational and prospective perspective”. He identified the business model elements (the economic viability; legal requirements) that make the reuse possible. of a company to manage reverse logistics for nuclear supply, to rely on partnerships, and assess the effective amount of batteries for reuse in stationary applications as well as the end-of-use properties. 2016) identified and validated with experts the functional and non-functional requirements for recycled batteries from EV to stationary applications. Based on a battery expert interview and literature (Ahmadi et al. 2014; Bauer et al. 2016; Beverungen et al. 2016), the repurposing process appears to include the same steps as reuse strategies: inspection and sorting, cleaning, dis-/ recompilation, storage, reuse of operations and testing.
The recycling step will mainly depend on reconfiguring the various components and sub-assemblies of the products and include a few product developments to then meet new requirements or connect the components in the new way.
Repurposing: Definition and Advantages
However, there are also remanufacturing processes that cannot return the initial performance to the product. This strategy should complete the list of reuse strategies and contributes to extended producer responsibility in the whole environmental consciousness equation (European Commission 2008). Company's responsibility at the end of the first end of use is transferred to the second life of the products.
This can be done in as many cycles as possible until it is transferred to the material recycling process. When the repurposing is properly implemented, the strategy is determined to be more environmentally friendly and less cost effective than manufacturing products from raw materials. The main difference is that the diagnostic phase about the quality of the used products collected (the product health) must be much more detailed and very intelligent in the pursuit of orienting the core to the most adapted transformation process.
Another difference of course lies in the technology of transforming the used product into a completely different product that needs to be developed, which then turns out to be easier in terms of reuse.
Short Discussion on Design for Repurposing
The roles of cleaner production in the sustainable development of modern societies.Journal of Cleaner Production. Figure 1 gives an example of which modules can be considered in the context of SPD (eg environmental impacts of electronic recycling). They can be used in the early stages, but are less useful for decision making for specific design problems.
Comprehensive collections of design guidelines have long existed in the environmental field (Telenko et al. 2016). In addition, organizing tools help to structure the design process by involving multiple stakeholders in the form of workshops or structured interviews. Life cycle-oriented properties can be understood analogously to the term life cycle inventory, which is used in the context of life cycle assessment to assess environmental sustainability.
The challenge here lies in choosing the right method for each task along the way in the product development process. The challenges described are also summarized in Fig.3 and are seen by the authors as a useful frame of reference for implementing sustainability objectives in the design process. Therefore, new approaches to decision support for this purpose are presented in the following chapters that deal with these aspects.
Breakdown of Sustainability Targets for Product Architecture Decisions
The customer value depends on the total cost of ownership (life cycle costs) of the electric bicycle. However, there are also other factors to take into account, such as functionality, which can be improved by the possibility of expanding the electric bicycle (for example with a more powerful motor or an extra roof). To reduce overall emissions, the production phase of the electric bicycle must be taken into account, as it accounts for almost half of the total greenhouse gas emissions from an electric bicycle (Neugebauer et al. 2013).
The most important contribution of modularization to the reduction of GHG emissions in production is to increase the time that the product can be used (service time), since a longer period of use ultimately reduces the amount of products that need to be produced . In addition, remanufacturing or reuse are possible measures to increase the service life of the product. Both End-of-Life (EOL) options can be promoted by increasing the ease of disassembly or by grouping components in such a way as to improve component sorting (eg by grouping components with the same materials).
Because of this multitude of effects, it can be difficult to find an appropriate system boundary for strategic modularization decision-making.
Model Based Reduction of the Solution Space
Configuration options from predecessor products can be used as a basis for identifying solution options (Buchert et al. 2016). Furthermore, the durability of the pedelec frame in the use phase was chosen as the second objective. Figure 7 gives an example of how the data model for a decision support tool can be structured.
The CO2 emission for forged material, for example, can be calculated from the property in terms of constant CO2 emissions per kg of material processed. The benefit of this approach is that all (discrete) values for a characteristic can be automatically evaluated repeatedly even if the required information is distributed between different IT tools. A more detailed description of this first model prototype can be found in the publication of Stark and Pförtner (2015).
A discussion of how the use case can be extended to assemblies and entire product systems can be found in Sect.5.
Guidance for Achieving and Proving Compliance with Sustainability Targets
Therefore, a comparison of variants for the drive concepts regarding CO2 emission and cost is necessary for the process of reporting results at a milestone towards the end of the conceptual design phase. Furthermore, it considers the type of objective that the method can address (e.g. addressed sustainability aspects or quantification of the objective). The last chapters presented different approaches to how the challenges of integrating sustainability goals into the design process (summarized in Fig. 3) can be solved.
For the specific case of modularization, it was shown how the decomposition of sustainability design goals can be supported by qualitative causal diagrams (see section 4.1). By following this approach, solution configurations can be identified that are consistent with a set of sustainability goals. In this pursuit of a deeper understanding of the product's interrelationship with sustainability impact, Sect.
By providing a selection scheme for SPD methods, the best-suited approach can be assigned to the tasks required to prove that sustainability design targets have been met.
