Estimating the Cutting Characteristics of Spiral Tap - Tool Edge Temperature and Fluctuation of Cutting Forces

A method for estimating the cutting characteristics of spiral tap by fluctuation of cutting forces is proposed. The behavior of torque and thrust in tapping is influenced by the change of cutting state. Therefore in this method the fluctuation of cutting forces is depicted in the torque-thrust plane in which the horizontal axis and the vertical axis indicate thrust and torque respectively. Tapping of stainless steel AISI 304 was conducted with several coated spiral taps attached to an axial floating tap holder. The tool edge temperature was also measured by a two-color pyrometer with an optical fiber. When the fluctuating of forces in the torque-thrust plane was similar to a theoretical pattern, the surface of thread did not have obvious geometric damage. In this cutting conditions, there is a strong correlation between tool edge temperature and cross-sectional cutting area.