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In my previous blog post on design for disassembly (DfD), I discussed how recycling rates can be increased by designing consumable products from the ground up with DfD principles:

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

In the first blog of three I focussed on minimising the number of different materials in a product to reduce or eliminate the number of disassembly steps required to separate and dispose of materials into their respective recycling streams.

In this post I discuss how consumer products can be designed to enable an efficient disassembly process for recycling or repair by the more careful selection of joining methods and smarter design.

Faster fasteners and fits

Fasteners such as screws, bolts and nuts are a convenient way to assemble products. However, each fastener requires unfastening, which takes time and often tools to achieve, putting the consumer off the process. To increase the ease and speed of disassembly, designers need to be sparing and intelligent with their use of fasteners. Other than simply minimising the total number of parts and fasteners the following design practices can be followed:

  • Use a single fastener to assemble multiple parts
  • Prefer standard and similar over dissimilar and proprietary fasteners
  • Co-locate the fasteners where possible i.e. same plane or component
  • Use screws rather than nuts and bolts

For joins between plastic parts, substitute fasteners with plastic fit features such as snap fits and friction fits. Design these features so they do not require tools and can be fitted and un-fitted many times without breaking. Using a friction fit is an excellent way to join two parts without fasteners, however if the fit is too tight (e.g. press fit) then the consumer may not be able to separate the parts.

Adhesives present a serious challenge for consumers looking to disassemble products and should be avoided or substituted for water soluble or heat reversible adhesives.

Smarter design for FMCGs

If DfD is considered in the early stages of the design process, i.e. the specification, then more elegant solutions can emerge. Cambridge Consultants’ DropTag, a low cost condition monitoring device, was designed to be disassembled repeatedly by the consumer for data acquisition, repair and disposal. The figure below shows the DropTag with the front cover removed, exposing the circuit board and battery. The battery can be easily and intuitively removed by using a boss feature on the inside face of the front cover, which doubles as a disassembly tool, to push the it from under the circuit board and up a ramp feature.


DropTag - Designed for Disassembly

This kind of approach can be translated to FMCGs. Disposable razors are well cited as villains of recycling; 2 billion are thrown away every year and they cannot be recycled due to the tenacious assembly of the steel blades and the plastic housing. The figure below shows how the inclusion of a slot in the housing and re-purposing the cover into a disassembly tool could be used to enable easier separation of the blades from the plastic body. Safety issues surrounding the disposal of sharps blades need to be considered further but this demonstrates how DfD can be easily applied to a range of problem products.



However, following these DfD principles to make separation of materials in consumer products does not guarantee that the consumer will actually do it, especially if the process is not perceived to be easy. The subject of my final blog in this series discusses how disassembly of products at the end of their useful life can be made both compelling and intuitive.

Alfrew Newman
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.