B. Willems’s research while affiliated with KU Leuven and other places

By repairing and reselling used products, reuse centres aim at creating low-skill jobs while offering low-cost and environmentally beneficial products. However, due to a combination of decreased efficiency of worn-out products and technological progress embodied in new products, lifetime extension of old products is not always the most beneficial scenario from an environmental nor an economic point of view. This paper investigates this trade-off for the case of washing machines in a Belgian context. For selected types of washing machines, critical reuse ages are determined above which reuse is environmentally or economically undesirable. A sensitivity analysis shows that these critical reuse ages are often sensitive to small changes of the input parameters.

The productivity associated with commonly available disassembly methods today seldomly makes disassembly the preferred end-of-life solution for massive take back product streams. Systematic reuse of parts or components, or recycling of pure material fractions are often not achievable in an economically sustainable way. In this paper a case-based review of current disassembly practices is used to analyse the factors influencing disassembly feasibility. Data mining techniques were used to identify major factors influencing the profitability of disassembly operations. Case characteristics such as involvement of the product manufacturer in the end-of-life treatment and continuous ownership are some of the important dimensions. Economic models demonstrate that the efficiency of disassembly operations should be increased an order of magnitude to assure the competitiveness of ecologically preferred, disassembly oriented end-of-life scenarios for large waste of electric and electronic equipment (WEEE) streams. Technological means available to increase the productivity of the disassembly operations are summarized. Automated disassembly techniques can contribute to the robustness of the process, but do not allow to overcome the efficiency gap if not combined with appropriate product design measures. Innovative, reversible joints, collectively activated by external trigger signals, form a promising approach to low cost, mass disassembly in this context. A short overview of the state-of-the-art in the development of such self-disassembling joints is included.

To achieve a sustainable growth, it is necessary to pursue the decoupling of economic welfare from the use of virgin resources: a shift from a linear economy to a closed-loop economy is required. Consequently, adaptation processes such as maintenance, repair, upgrading and remanufacturing are needed. This paper presents a dedicated method to assess the lifetime prolongation capabilities of products by evaluating their design. The method determines the suitability of a product to undergo adaptation processes and the improvement potential within the design of a product, its components and joints, using an aggregated metric.

To make disassembly cost-efficient, one-to-many fasteners are needed. These so-called active fasteners use advanced materials or structures as a catalyst for disassembly, allowing multiple assemblies to separate simultaneously after exposure to specific external triggering conditions. Using topology optimization this paper explores the alternative configurations of pressure-based active fasteners. The optimization problem is first solved in the 2D space for a snap-fit like design. Based on these results the problem was extended to 3D and solved. Similar as for the 2D results, a detailed finite element verification was conducted which proved the optimized structure shows an increase of the disassembly efficiency with 200–250% compared to the initial non-optimized structure measured in displacement of the snapping features. As such, this paper shows that for future manufacturing businesses, active fasteners promise to be a valid alternative for shredding. Since the model can easily be modified for other trigger conditions or design configurations, the proposed approach proves to be suitable to develop different types of one-to-many disassembly fasteners.

Using topology optimization this paper explores alternative configurations of pressure-based active fasteners. The 2D and 3D optimization problem is solved for a snap-fit like design. A detailed finite element verification is conducted, the theoretical designs are translated into producible components and preliminary concepts how to manufacture the designs are presented.

Industrial production inevitably results in an environmental impact. Energy consumption is responsible for a substantial part of this impact. Currently, machine designers spend little attention to minimising the energy consumption, since their primary focus is on the well-functioning of the machine. This paper indicates the potential for energy improvement measures. According to Gutowski et al [1], a major part of the total energy consumption of a machine does not depend on the production rate, but is fixed. This paper searches for possible measures to reduce this independent fraction. Another aspect is the importance of the machine occupancy: in a lean manufacturing approach, machines only operate when a product order is released. This implies a constant availability of the machine in a stand-by mode, since high flexibility is required, while the actual processing time may be limited. This paper audits these energy aspects for two discrete part producing machines types: a press brake and a multi-axis milling machine, and proposes initial design improvements to reduce the overall energy consumption. The possible economical and environmental impact of such energy saving measures from a life cycle perspective is quantified in order to allow cost-benefit analysis.

To make disassembly cost-efficient, one-to-many fasteners are needed. These fasteners use advanced materials or structures as a catalyst for disassembly, allowing multiple assemblies to separate simultaneously after exposure to specific external triggering conditions. Using topology optimization this paper explores a systematic development strategy for structure based one-to-many disassembly concepts

It is widely recognized that disassembly-based product End-of-Life strategies, such as component reuse or simple fraction material recycling, are environmentally beneficial. However, current disassembly costs hinder a widespread application of these strategies. This paper quantifies the disassembly time reductions required to achieve economic feasibility of systematic product disassembly. A modelling framework, based on linear programming, is used to investigate the effect of reducing the expected disassembly time and cost on the selection of the optimal End-of-Life strategy. The problem is optimized from an End-of-Life treatment facility point of view. All findings are based on the Belgian cost and price information captured in spring 2004. The linear programming model shows that for small products from the Waste of Electric and Electrical Equipment (WEEE) category disassembly-based End-of-Life strategies will hardly become optimal, while for medium- and large-sized products, this scenario can be made optimal if a substantial disassembly time reduction is achieved. Possible strategies to realize such reduction are briefly sketched.

From an economic point of view the productivity associated with commonly available disassembly methods today seldom makes disassembly the preferred end-of-life solution for massive take back product streams. In consequence systematic reuse of parts or components, or recycling of pure material fractions are normally not achievable. Economic models demonstrate that the efficiency of disassembly operations should be increased an order of magnitude to assure the competitiveness of ecologically preferred, disassembly oriented end-of-life scenarios. Using fully automated disassembly techniques does not allow to overcome this efficiency gap if not combined with innovative reversible joints. Enhanced disassembly principles, in which external trigger signals allow to simultaneously reverse the action of multiple fasteners, forms a promising approach to low cost mass disassembly. In this paper a state-of-the-art of these emerging techniques is sketched, categorising the fasteners according to their generic applicability and the degree of imbedded automation of the triggerable disassembly activity. A number of perspectives for innovative reversible fasteners are sketched as a contribution to this promising paradigm of selfdisassembling products.