Investigation of the Reversal Loads in a Tapping Process

Abstract

In the manufacturing industry, tapping tools are widely used for threading screws in drilled holes. It is expected that cutting loads would be affected by both the geometry of the tools and the cutting parameters in a tapping process. However, it is thought that such a simple mechanism does not exist. It is supposed that the tapping tools will encounter different loads while they are going forward and backward in the holes. Therefore, the unsteady loads that can lead to breaking the tools in the holes are important. In this study, tapping tests were performed on AISI 1050 steel. TiN-coated and uncoated HSS-E tools were used to cut M10 standard right screws on test parts. For this purpose, the test parts were thoroughly drilled with ø8.5 mm HSS drill bits. Then the tapping tools, which were manufactured in four different forms, were used to thread the screws in the holes. The tapping loads that are axial forces and torques were measured with a standard dynamometer. The experiments were carried out by using cutting fluid on a CNC milling machine. In conclusion, it is figured out that the axial forces and torques while the taps are going down the holes are more different than in the period the taps are going up the holes. While the tools were coming back at the end of the threading process the torques decreased, but the axial forces increased. Moreover, the heights values for the axial force and torque occurred by the TiN HSS-E tools that got straight-flute.