Design Improvement Of Miniature Boring Tools Using Process Models

Official URL: https://risc01.sabanciuniv.edu/record=b3205836

Machining of precise small holes, an essential feature in parts used in a variety of industries like aerospace and medical, is made possible by miniature boring tools. Due to the tight dimensional tolerances and demand for high-quality surface finishes, the hole enlarging process necessitates the use of miniature boring tools and precise cutting conditions. However, the delicate geometrical properties of small boring tools make them vulnerable to static and dynamic deflections. Additionally, the hole enlarging process, which is increasing the diameter of previously drilled holes, necessitates close attention to maintaining the desired level of surface finish, along with achieving improved hole dimensions and tolerances such as excellent circularity and cylindricity values. Since cutting forces, particularly the radial force, induce the deflection of tools in the process of cutting, the principal aim of this study is to reduce the forces and enhance the stability of the tool. The geometric features of the tool, depth of cut, and feed rate values are critical factors that impact the chip geometry and, consequently, the cutting forces. A force model and a chatter stability model were developed according to the geometric properties of the cutting tool. The developed models are validated by experiments. The experiments involved the measurement of cutting forces, tool wear, surface roughness, cylindricity, and circularity of the workpiece. Furthermore, modal tests were conducted, and stability limits, and the tools’ clamping stiffness were measured through experiments. The results of the study indicated that the predicted and experimental values exhibited a high degree of agreement. Therefore, through implementation of the established force model, the impact of the geometric characteristics of the cutting edge on the cutting forces, and ultimately, on the quality of the surface finish was examined. This investigation was carried out with the objective of improving the design of the miniature boring tool’s edge geometry to achieve accurate holes in the hole enlarging operations.