Performance of cutting fluids during face milling of steels

An experimental investigation on the performance of an emulsion of mineral oil, semi-synthetic and synthetic cutting fluids when face milling AISI 8640 steel with coated cemented carbide tools were carried out. Dry cutting was also performed for comparison purpose. Tool life, power consumption and surface roughness were monitored during the machining trials. In order to study the cooling ability of the cutting fluids, cutting temperatures were measured during turning of AISI 1020 steels, using the tool–workpiece thermocouple method. The highest cutting temperatures were generated when machining dry, followed in a decreasing order, by the application of the synthetic, emulsion of mineral oil and semi-synthetic cutting fluids. A reverse effect was found in terms of the power consumption during machining. The best tool life was recorded when machining dry, followed, in a decreasing order by the application of synthetic and semi-synthetic cutting fluids. Comb cracking was the major failure mode of the cutting inserts during machining. Dry machining produced slightly better surface finish than machining in the presence of cutting fluid.