Sustainable manufacturing metal cutting fluid – from mineral oil to vegetable oil

Abstract

Metal cutting fluids (MCFs) are widely used in industry. This raises the concerns about sustainability, biodegradability and the associated health risks. Numerous studies show the benefits of using vegetable oil-based over mineral oil-based MCFs. Having numerous advantages like lower production cost and lower environmental impact, the vegetable oil-based MCF could become the sustainable alternative for the conventional mineral oils. This thesis work aims to evaluate the performance of four mixtures of neat vegetable and mineral oils in the machining of free-cutting steel (FCS). The work is primarily focused on the tool wear, the surface roughness of the machined components, and the microstructure of the raw materials. The results show no significant difference between the wear mechanisms of the tools, predominant being the adhesion wear. The minimum tool wear on the coated carbide inserts occurred when machining with 100% neat vegetable oil and only slightly increased as the volume percentage of mineral oil in the cutting fluid increased. The surface roughness was not affected by the changes in the cutting fluid. The microscopic analysis revealed that the microstructural components of the free-cutting steel include ferrite and pearlite together with lead (Pb) and manganese sulfide (MnS) inclusions.