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Consumers have become very good at recycling; in the UK the mass of waste sent to landfill has decreased by 40% since the turn of the millennium. There is greater social responsibility with regards to waste and many large companies are starting to take steps to prevent resources getting into landfills. However recycling rates have stalled at around 43% for the last couple of years.

As I discussed in a previous blog, one contributing factor for this is that many ostensibly “disposable’ products which contain recyclable materials are not able to be recycled due to the way they are assembled. High volume products such as lighters, disposable electric toothbrushes and razor blades all contain a mixture of recyclable plastics and metals. What can be done to improve the recycling rate of these tenacious assemblies?

One answer is to design the products so they can (and will) be disassembled and recycled by the consumer at the end of their useful life. This can be achieved by making Design for Disassembly (DfD) part of the design specification. This blog, the first in a series of three, will discuss the first of three DfD design practices:

  • Reducing the number of different materials
  • Enabling an efficient disassembly process
  • Making disassembly an intuitive and compelling process

Reducing the number of different materials


design for disassembly

Reducing the number different of materials reduces the number and complexity of operations required to separate and dispose of materials into their appropriate recycling streams. Ideally everything would be made of only one type of material however this would make for some ugly and dysfunctional products! However, some products simply haven’t been designed with this objective in mind and could be modified to be made from fewer or a single material.

For example, hand soap dispensers use a metal spring in their pump mechanism where a plastic spring, made of the same PET plastic as the container, will do the job for the approximately the same cost. It took 10 minutes (far longer than the average consumer would persevere) and a screwdriver to liberate the spring from the container pictured right.

We calculated the minimum force required to operate the pump and the captured the spatial constraints of the container. Then we designed and 3D printed a new PET plastic spring (see below), fitted it in the original soap dispenser and tested it. The plastic spring performed as well as the old metal spring and has survived a couple of weeks (and counting) of vigorous testing in the first floor bathroom at Cambridge Consultants.


designed for disassembly

This new plastic spring, which weighs less than a gram, could cost the same or less the metal springs if injection moulded in similar volumes. What we have shown in this example is that, with a little ingenuity, that a disposable product can be redesigned to be of a single material and thus simplifying disassembly (eliminating in this case), enabling the consumer to recycle it effectively.

In my second blog post of this series I discuss how designers can enable an efficient disassembly process.






James Westley

James is a Senior Engineer within our Mechanical and Analytical group with 5 years of experience in the energy sector. He is a composite specialist interested in projects which promote sustainability.