The objective of this study is to establish the comprehensive analytical relationship between acoustic emission and fundamental parameters of the orthogonal cutting process. The sources of acoustic emission in the orthogonal metal cutting process was identified as deformation in the shear zone and sliding friction at the chip-tool interface. The validity of this relationship is evaluated by a series of tests varing cutting speed and rake angle for A16063 tube. Strong dependence of the RMS voltage of acoustic emission on cutting speed and rake angle was observed. It was also found that the percentage contribution of AE energy at each zone for the total AE activity is constant in accordance with the change of cutting speed. The relationship between the RMS of acoustic emission and the fundamental cutting parameters was modified in order to be utilized independent of rake angle.