Tribomechanical effects of cutting fluids in high-speed cutting

Abstract The supply of cutting fluid (CF) has numerous positive effects on the cutting process. However, supplying CF to the contact zone at high pressure is associated with a high energy consumption for the pumps. Knowledge of the optimum CF-pressure p therefore offers the potential to optimize cutting processes. Hence, the basic mechanisms of action of CFs on the cutting wedge are the subject of current research. Knowledge about the tribological effects of CFs exists, especially at low to medium cutting speeds (v c ). Although an increase in cutting speed (v c ) leads to an increase in productivity, the increased chip flow velocity against the direction of the CF-supply leads to a reduction of the main effects of CF. In this work, high-speed video analyses and force measurements are used to investigate the mechanical cutting wedge load at cuttings speeds of up to v c = 350 m/min. The knowledge is supported by basic tribological investigations using a special open-contrarotation tribotester. Cutting fluid pressures (p) of up to 80 bar are investigated. It is shown that a CF-supply increases the maximum normal and tangential stress on the cutting wedge due to a reduced contact length at p = 80 bar for all investigated cutting speeds. Using the tribotester, it was also possible to show that the coefficient of friction (µ) can be reduced by the cutting fluid pressure (p) at high relative speeds indicating a reduces mechanical load in the secondary shear zone.