Effect of the compressed air flow in minimum quantity lubrication on wear, tool life and machined surface roughness

Pressure of the compressed air flow in Minimum Quantity Lubrication (MQL) is one of the most important factors to determine the capacity to create tiny droplets of lubrication in the form of mist, direct them into the cutting area for cooling and lubricating purposes and at the same time push the chips out of the cutting region. Furthermore, the effect of Minimum Quantity Lubrication (MQL) on yield of the machined process and quality of machined surface depends considerably on the machining methods. Research results published in this paper indicates that appropriate pressure of compressed air flow of 4 bar in two typical machining processes: slot cutting with the use of two-lipped end mills (finger-cutter) and drilling is the main reason for a reduction of the tool wear on flank face to a minimal value resulting in much longer tool life and the lowest machined surface roughness in the manufacturing conditions of research.