A new approach to analysing machined surfaces by ball-end milling, part II: Roughness prediction and experimental verification

This paper presents a procedure for the evaluation of maximum surface roughness using the ridges analysed in part 1 of this paper. Maximum surface roughness is predicted for the plane cutting mode of ball-end milling. Two types of cutting modes, i.e., unidirectional mode and bidirectional mode, are investigated. The various cutting conditions in plane cutting are simplified employing the concept of the path interval ratio, f(p)/f(t). In addition, mathematical expressions for calculating maximum surface roughness have been described for each case. The predicted results show that the geometrical surface roughness of the bidirectional mode is usually larger than that of the unidirectional mode differing from the results of the conventional roughness model. Maximum roughness and the shapes of the cut remainder are affected by path interval, feedrate and cutting mode. Experiments are carried out at various cutting conditions for both cutting modes. A high level of agreement between the expected surface roughness and measured value confirms the validity of the proposed method.