The effect of superimposed low-frequency modulation on lubrication in machining

A study has been made of the effect of an externally imposed, low-frequency modulation on the action of lubricants in machining. It is shown that in conventional machining, lubricant action is essentially confined to the edges of the chip-tool contact, with little or no change in the friction condition over much of the rake face. However, the effectiveness of lubricant action is significantly enhanced when a controlled low-frequency modulation of sufficient amplitude is imposed in the direction of cutting. Measurements show that the friction coefficient on the rake face is reduced by a factor of two to three in the presence of such a modulation. The nature of metal transfer onto the rake face is also substantially changed by the modulation.