Life cycle assessment of cutting tool coatings

The majority of cutting tools used in industry are coated to improve their performance. Despite this, the environmental impacts of cutting tools and their coatings have been widely overlooked. This paper quantifies the embodied energy and Global Warming Potential (GWP) of cutting tools, with an emphasis on the coating process, by conducting a cradle-to-gate Life Cycle Assessment (LCA). Chemical Vapour Deposition (CVD) and Physical Vapour Deposition (PVD) coating methods have been evaluated, focusing on TiAlN, AlTiN, TiN, AlCrN, and uncoated tool cases. The embodied energy and GWP per unit area for the Cathodic Arc Evaporation PVD case varied between 7.75 – 67.16 Wh/mm2 and 1.56 – 13.55 kgCO₂-eq/mm2, respectively, depending on the coating batch size. The Magnetron Sputter Deposition PVD case recorded the lowest embodied energy of 3.87 Wh/mm2 and GWP of 0.78 kgCO₂-eq/mm2. The CVD deposition showed the highest embodied energy of 11.04 Wh/mm2 and GWP of 2.56 kgCO₂-eq/mm2 for a similar batch size. The analysis indicates that when coating emissions are compared to the carbide tool emissions, the increase in tool life due to coating outweighs the increase in emissions by coating the tool in most cases.