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The cutting fluids contributed for removing chips, cooling, and lubricating, on the other hand, are harmful to the environment. The minimum quantity lubrication technique (MQL) in machining operations proved to be suitable in addition to minimizing the environmental impact. The present work is focused on the drilling of electrolytic copper using biodegradable oil as cutting fluids applied by the MQL technique. The specific cutting pressure, burr height, and maximum diameter were measured varying the cutting parameters, cutting speed, feed, and lubrication condition (dry, flooded, and MQL). A statistical analysis was utilized to determine the influence of cutting parameters in the variables measured. The results indicated that the second-order interactions have a significant influence on the specific cutting pressure and in burr height. The lowest burr height was obtained using flood and MQL. The MQL system demonstrated the lowest specific cutting pressure, while the flood exhibited the best performance for diameter analysis. In addition to this, it can be confirmed that the MQL technique may replace the flooding drilling (abundant flow), minimizing the environmental impact.

Applications for composite materials are constantly increasing because of their lightweight combined with a high modulus of elasticity. Thus, the drilling of such materials is cause for concern for the scientific community since these components need generally to be fixed and assembled. Dimensional variations and the presence of burr are some of the problems that commonly arise due to the drill action in the composite material. Such problems should be minimized because it can compromise the quality of the final product. The present work studies the drilling of a sandwich composite material consisting of aluminium and polyethylene core (PEALL). The drilling tests were carried out using a TiO2-coated high-speed steel drills (HSS drills) deposited by sol–gel process. In order to optimize the hole quality, the influences of the TiO2 coating and the drilling parameters (speed and feed) are analysed. The thrust force, burr height and maximum diameter are collected to statistical study (analysis of variance (ANOVA)). The results underline that the TiO2-coated tool exhibits the best performance and improves the hole quality. Thus, the sol–gel method is a promising technique to coat the complex geometries of the HSS tools.