Study on Micro-Forming Taps with Unequal Fluteless Spacing

Abstract

Tools with unequal fluteless spacing (UFS) feature are used to cut different materials. The UFS tool and a traditional tool differ in terms of the angle between the two cutting edges. The UFS tool experiences smaller axial and radial cutting forces than the traditional tool so cutting vibration is reduced, tool life is increased and the surface roughness of the workpiece increases. This study uses the smaller hole diameter (D), spindle speed (N) and cutting fluid concentration (C) for the central composite design (CCD). MINITAB statistical software is used for the second-order response surface modeling of the maximum thread filling rate (f) and the minimum torque (T) for micro-forming M1.2 mm taps using UFS on AL-7075 aluminum alloy. The analysis of variance (ANOVA) results for f and T show that D and C are the important parameters that affect f, and D, N and C significantly affect T. Compared with the predicted conditions, the errors in f and T for the experiment are 2.51% and 2.25%, respectively. This study shows that the two second-order mathematical models that are derived using CCD and the response surface method (RSM) feature good prediction accuracy.