Repository logo

Making More Cars with Less Metal



Change log


Horton, Philippa Maia 


Reducing sheet metal yield losses in automotive manufacturing would reduce material demand, providing environmental and financial benefits. This thesis explores material efficiency from four perspectives:

  1. The opportunity for improvement: A part by part analysis of yield losses for every sheet metal component in a vehicle highlights nine material efficiency strategies. An industry study finds that on average only 56% of sheet metal purchased is used on the vehicle. Improving material utilisation to best practice of 70% would save £8 billion and 25 million tonnes of CO2 annually.

  2. The potential to realise this opportunity: A design process to improve material efficiency is trialled within an automotive manufacturer and identifies opportunities of 20%. However, only 3% improvement is realised since the material efficiency opportunity is locked in at the start of the design process, where resource is not currently allocated. Earlier consideration of material utilisation is required.

  3. Material efficiency within the circular economy: All existing metrics for recycling in sheet metal forming processes are mapped onto a diagram. A case study demonstrates that existing recycling metrics, do not promote the reduction of yield losses. Considering recycling process efficiencies rather than recycled content would enable recycling rates to be measured without penalising material efficiency.

  4. Design for material efficiency: There are currently no suitable tools to inform process selection and geometry decisions for material efficiency. To address this, a novel set of experiments is conducted. These experiments identify a trend between the maximum draw depth and three critical radii. This trend could form a geometry based formability guideline which would enable design for material efficiency.

Approaching material utilisation from these perspectives gives greater certainty of the saving opportunity for sheet metal material efficiency and clarifies the priority of material efficiency compared to other strategies to meet global climate change goals.





Allwood, Julian Mark


Material Efficiency, Sheet Metal, Forming, Yield Losses


Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge
Sponsored by Jaguar Land Rover