Modeling of tool vibration and its effect on roundness and surface roughness of hole in helical milling of Inconel 718

Relative vibration between the cutter and workpiece has an influence on the surface generation and dimensional accuracy. In the present work, prediction models were developed for roundness and surface roughness of hole in terms of amplitude and frequency of tool vibration. The proposed methodology carried out a theoretical investigation on the effect of tool vibration components in X- and Y-directions on the mill cutter end point to estimate hole roundness and surface roughness. Series of helical milling experiments were conducted at different levels of spindle rotational speed, cutter orbital speed, and axial depth of cuts using 10- mm and 8- mm diameter mill cutters on Inconel 718. Predicted values of the roundness and surface roughness of hole were compared with predicted values and verified accuracy of the proposed prediction models. The experimental results indicate a good agreement with the predicted value. At spindle rotational speed of 2000 r/min and cutter orbital speed of 50 r/min, the measured and predicted values of the roundness were found to be almost same as the required roundness. The surface roughness was found to be very less at 50 r/min of cutter orbital speed.