Design efficiency calculation

Helps to reduce the overall number of components by focusing the design teams attention on the need for each part. Good for focusing team discussion.

At the core of many design for assembly analyses is an attempt to understand whether each component is important in order to reduce the overall number of parts. This analysis, although simple in concept can result in significant discussion about how parts can be combined and which parts are genuinely contributing to product function. The analysis looks at three aspects, with three high level questions for each:


Relative movement

Where there is relative movement between components, then it is likely that different parts are needed. However, this movement may be achieved in other ways, through plastic hinges, flexing or alternative jointing methods. If there is no relative movement, then there is a good chance that components can be combined.


Different materials

If different materials are used for components which do not move relative to each other, is there a good reason? What are the opportunities for combining these parts through an alternative arrangement?


Need for adjustment or replacement

Finally, although there may be no relative movement in operation, a component may require adjustment or replacement. Again, can this be achieved in other ways?

Having considered each component, it is possible to calculate an overall 'design efficiency' for the product or sub-assembly. As a rule of thumb, it is good to aim for >60%. However, the end number is less important that the discussion and debate along the way.


Design efficiency calculation


  • Tools which produce numerical answers can be dangerous - it is not the answer which is important, but the discussion and the teamwork to get there
  • Requires at least engineering and production involvement. Marketing involvement is beneficial when product functionality becomes an issue
  • Needs a design to analyse, either existing or at concept stage

For more information, please contact:

James Moultrie


T:  +44 1223 764830



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