Quality assessment of milling technology and the biocidal effects of SiO2 or TiO2 nanoadditives in cooling lubricant emulsions

Nanoparticles (NPs) of TiO2 or SiO2 (size of 10-25 nm) added to a cooling lubricant emulsion (CLE) have a positive effect on the machining process due to a reduction in the average friction coefficient, a reduction in the variance of the measured values and a reduction in the wear of the cutting tool resulting in increased durability. The functional properties of NPs were evaluated using two different CLEs - CLE1 with the majority content oxygen molecule and various amines; and CLE2 composed of oxygenated organic compounds comprising glycols and higher alcohols. Conventional face milling was selected as the machining process type with the cutting speed 119 m min(-1); rotor speed 600 rpm; feed per tooth 0.1 mm; feed rate per minute 60 mm; depth of cut 1 mm and width of cut 40 mm. The addition of spherical SiO2 NPs and TiO2 NPs with a flat surface texture with smooth edges led to a reduction in wear, in the sticking region there was no evidence chipping, cracking or peeling of the coating. The different compositions of CLE1 and CLE2 influence the biocidal effects of the NPs on bacteria cells; CLE1 with SiO2 of 56.6%, and with TiO2 of 18.4%; CLE2 with SiO2 of 26.5%, and with TiO2 of 55.3%. The presence of NPs in the CLEs does not increase the cytotoxic effect on mouse fibroblast cells; however, the composition of CLE1 and CLE2 affects the cytotoxicity for mouse fibroblast cells; CLE1 has an up to 59.6% higher cytotoxic effect than CLE2.