Investigating chatter vibration in deep drilling, including process damping and the gyroscopic effect

This paper investigates chatter vibration occurring in drills for deep hole machining. A model is developed that considers process damping occurring due to the interference between the drilling flank surface and the workpiece surface. Furthermore, the gyroscopic effect due to the rotation of the tool is included. Borders of stability, which indicate critical radial widths of cut (RWOC) at each spindle speed, are obtained analytically from the eigenvalues of a frequency domain equation. Results at this stage show good agreement with the experimental data. In addition, a numerical method is used to simulate the tool path at different RWOC and spindle speeds. Numerical simulation agreed with analytical results. The hole form produced by the tool tip is investigated at different speeds and RWOC with respect to borders of stability. These investigations show that spindle speed selection is an important manner in industrial practice. That is, even below borders of stability, where chatter does not occur, spindle speed selection affects roundness, concentricity, and surface roughness of the hole.