Design for repair and maintainability

Recently, I have been thinking about design for repair and maintainability.  The three ‘R’s of sustainability remind us to Reduce, Reuse, Recycle, but ‘Reuse’ can be a challenge when so many products are not designed with maintenance or repair in mind.  Home printers are a good example, with huge numbers of printers ending up in landfill after a relatively short life; often due to blocked print heads that are either impossible or too expensive to replace.

The design of a product has a huge impact on its maintainability. The domestic lightbulb is a great example – the bayonet fitting is easy to insert and remove with a quarter turn, it provides structural support for the bulb and makes the electric connection in the same action. No tools are required to install or remove it, and you cannot install it the wrong way round.  By contrast, replacing a car headlamp bulb usually requires a complex sequence of disassembly and reassembly steps, using specialist tools and with poor visibility and ergonomics. If you’ve never tried, take a look at the instructions  for an Audi A4 here.

Design for maintainability has existed as a discipline since the 1960s when many military and aerospace standards were first developed [1 – 3] .  These standards provide guidelines on designing for accessibility and human factors,  as well as offering methodologies to predict repair time so that designers can compare the maintainability of different options before the design is finalised. Today, advanced CAD modelling tools allow ergonomic assessment of maintenance tasks in a digital environment, so that the posture of  the maintainer and accessibility issues can be investigated at the design stage [4,5].

So why aren’t all products designed for maintainability? The problem is that other business drivers’ conflict with maintainability objectives. In the automotive industry, vehicle repairs represent a valuable income stream, so there is little incentive to design products that allow end consumers to perform maintenance themselves.  And manufacturers of high-tech consumer products want their customers to regularly replace their products with new versions, so there is no incentive to make it easy to repair them. New business models like servitisation integrate through-life services into the product offering,  aligning the incentives for sustainability with the overall business model. The TotalCare services for Rolls-Royce aircraft engines is a successful example, but this approach has not been as widely adopted as many had hoped.

I love the current initiatives to help end-users make their own repairs.  The iFixit website  and others provide free instructions on how to repair thousands of items, and everyone can contribute; they also sell the tools that are required  for disassembly. Repair cafes are also gaining momentum, where volunteers help visitors to repair broken items.  Let’s hope these initiatives continue to grow in the future and that consumer demand will lead to more sustainable products.

 

[1] MIL-HDBBK-470A. Designing and developing maintainable products and systems, Department of Defense. Philadelphia: Navy Publishing and Printing Office; 1997.

[2] DOD-HDBK-791. Maintainability Design Techniques, Department of Defense. Philadelphia: Navy Publishing and Printing Office; 1988.

[3] MIL-HDBK-472 Notice 1. Maintainability prediction, Department of Defense. Philadelphia: Navy Publishing and Printing Office;1984.

[4] Lockett, H.L. and Arvanitopoulos-Darginis, K. (2017). An Automated Maintainability Prediction Tool Integrated with Computer Aided Design. Procedia CIRP, 60 pp. 440–445.

[5] Lockett, Helen; Fletcher, Sarah and Luquet, Nicolas (2014). Applying Design for Assembly Principles in Computer Aided Design to Make Small Changes that Improve the Efficiency of Manual Aircraft Systems Installations. SAE International Journal of Aerospace, 7(2) 284 – 291.

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