Abstract: The theory of axial vibration drilling is systematically analyzed. The relation of each parameter and its effect on the machining process is discussed. The conditions of broken chip and the method of calculating chip length are given. The actual result is always smaller then the theoretical value in every cutting condition, but the difference is small. This lays down a theoretical foundation for quick selection of right axial vibration drilling parameters and successful automatic machining of deep holes.

Key words: broken chip condition, chip length, vibration drilling, drilling parameters, cut-in angle