Sustainability in machining: Eco-friendly turning of Inconel 718. Surface characterisation and economic analysis

Elimination or substitution of traditional lubricants results in the reduction of both operating costs and environmental impact associated with the use, filtration and disposal of metalworking fluids. However, traditional lubricooling are still widely used when machining difficult to cut materials, like Inconel 718, with the aim to increase tool life and obtain a surface with proper roughness. The need to move towards an eco-friendly machining pushed the authors to study the effects of alternative lubrication methods (Minimum Quantity Lubrication or Cooling and cryogenic one) on tool life, surface finish and machining costs, when turning Inconel 718. The material was machined with coated cemented carbide tools by a CNC lathe. Metal removing process was carried out under different cutting speeds while depth of cut and feed rate were kept constant. Economic analysis was also considered with the aim to evidence the most convenient condition. Minimum Quantity Cooling resulted in tool life and surface finish very similar to those obtained by conventional lubricooling, even if last one still remains the most convenient at economic level in the present case. (C) 2016 Elsevier Ltd. All rights reserved.