Scrap happens, but does it have to? On the potential of increasing machine component reuse
Doctoral thesis, 2017

The vision of the “circular economy” provides some guidelines for society to strive towards. In the circular economy, material resources are used and reused and recycled better, if not endlessly. Products are to require less material and deliver more function. In industry, manufacturers of all types of products and parts have started to investigate how they and their products can fit in.  The purpose of this study was to address the question – What can a component manufacturer do to improve the resource efficiency of its products through extending product lifetime and improving end-of-use management? To answer this question, the study focused on the key product of one component manufacturer, a bearing, a part that is used in many things mechanical. Mixed methods were utilized including material flow analyses to quantify downstream bearing material flows and interviews with customers of the component manufacturer to provide explanations about the fate of bearings, their obsolescence, and the possibility to remanufacture and reuse more of them and recycle them in a better way.  Results of the study reveal that there are large opportunities for the component manufacturer to remanufacture more and that there are sizable environmental benefits to doing so. Most notably, bearings in industrial use oftentimes become scrap not because they fail but because an end-user deems them to be untrustworthy. In these situations, remanufacturing offers a way to restore the bearings but often, end-users do not choose that option.  End-users make obsolescence and remanufacturing decisions with consideration to risks at the system-level and their ability to make a thorough assessment is limited by lack of time and information. These and other lessons learned from this study demonstrate the kind of low-hanging fruit that component manufacturers may have but indicate that picking it may require changes to the way they do business.


circular economy




KC-salen, Kemihuset
Opponent: Professor Tim C. McAloone, Department of Mechanical Engineering, Danmarks Tekniske Universitet


Derek Diener

Chalmers, Energy and Environment, Environmental Systems Analysis

Diener, D., Kushnir, D. and Tillman A.M. Scrap happens— Industrial end-users and their role in product obsolescence and remanufacturing outcomes

Diener, D., Tillman, A-M, Ljunggren-Söderman, M., Willskytt, S., André, H. Breaking down obsolescence, Submitted to a scientific journal in the field of industrial ecology

Scrap happens. This saying, as well as its older cousin, Sh&% happens, can be said nonchalantly in order to explain S#%& without going into much detail. S#&/% happens. It just does. There’s not much we can do about it now. Usually though, there’s a lot more to it and each time Scrap happens is unique. Scrap happens because a person determines that an object is scrap; it’s too ugly, too risky or just not functional enough. That’s just the way it goes, the object is used, scrapped and recycled … that’s good enough, right? This thesis poses this question by studying the life of an object that is a basic building block of many things mechanical, the bearing. Results of the study illustrate tangible opportunities to reuse more, extend objects’ lives, and reduce environmental impact. Lessons learned shed light not only on how Scrap happens but also, how reuse could happen much more often.

Subject Categories

Production Engineering, Human Work Science and Ergonomics

Other Engineering and Technologies not elsewhere specified

Environmental Management

Driving Forces

Sustainable development



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4299



KC-salen, Kemihuset

Opponent: Professor Tim C. McAloone, Department of Mechanical Engineering, Danmarks Tekniske Universitet

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