Environmental impacts of conventional and additive manufacturing for the production of Ti-6Al-4V knee implant: a life cycle approach

This paper explores whether additive manufacturing (AM) is more environmentally friendly than conventional manufacturing (CM) for the production of medical implants. The environmental impact of manufacturing the femoral component of a knee implant made from Ti-6Al-4V material was investigated. One AM method (electron beam melting (EBM)) and one CM method (milling) were analysed for the production of this part. A cradle to grave life cycle approach was utilised for each manufacturing method focusing on the primary energy consumption (PEC) and CO2 emissions. It was found that when the entire life cycle of the implant is considered, EBM is a more environmentally friendly method of producing the implant. This is mainly due to the complex geometry of the implant. For complex geometries, lots of waste material are generated using CM processes, whereas much less material is wasted using the AM process. The production of the raw material, Ti-6Al-4V, has a high PEC and associated CO2 emissions, so the amount of required raw material for either manufacturing method is the most important factor from an environmental perspective. Finally, the article presents the plans for future work and some remarks are concluded.