Abstract: Up to the present, all published vibration drilling chip breaking theories considered that in zero-phase-difference axial vibration drilling, chip breaking was impossible. This point of view was found improper by our experiments.
From tho point of view of kinematics, axial cutting depth at each point of the major cutting edge remains unchanged during the cutting process under ordinary conditions; chips would not be broken. However, when some ductile metals, such as industrial aluminum, are vibration drilled with relatively large vibration amplitude, special chip breaking phenomena appear, which favours the drilling process very much. Proceeding from the changing angle characteristics of vibration drilling, this paper proposes the new chip breaking theory, and some experimental investigations have been made.

Key words: vibration drilling, zero-phase-difference, ductile metal, chip breaking, chip process