Simultaneous effects of cutting depth and tool overhang on the vibration behavior of cutting tool and high-cycle fatigue behavior of product: experimental research on the turning machine

One of the major challenges in the manufacturing parts, especially metals, is turning with good/excellent surface quality, which has a significant effect on the fatigue strength of the industrial components. Selecting incorrect or unsuitable values of machining parameters leads to vibration instability in the cutting tool and as a result, excessive roughness is created on the product's surface. Therefore, one of the ways to reduce the roughness factor and increase the product fatigue life is to control the relative slip and vibration between the cutting tool and the workpiece. To achieve this goal, the authors attempted to investigate the simultaneous effects of tool overhang and cutting depth on the static and dynamic deflection of the cutting tool in vitro. After that, the surface roughness was measured in different workpieces. Also, to study the high-cycle fatigue behavior of products with different surface roughness, four-point bending fatigue test was performed and stress-life diagram (S-N) was obtained. In addition, Basquin coefficients were extracted in terms of surface roughness. Eventually, the mathematical relationship between Basquin coefficients and surface roughness was presented by employing multiple linear regression (MLR) technique. This work was also done to obtain the relationship between machining parameters, including cutting depth and tool overhang, and surface roughness, and finally mathematical relation of life estimation was presented via the studied parameters. Next, S-N diagram of CK45 carbon steel considering surface roughness of 2.07 microns was predicted using the proposed model and different orders (first-, second-, and third-order regression). Comparison of the predicted data with the test results indicated that the mathematical model presented in this research is well able to evaluate the fatigue life of carbon steels with different roughness levels.