Thesis defense of Harry Yasir Otalora

Thesis defense of Harry Yasir Otalora

Title of the thesis: "Cutting forces prediction in orthogonal turn-milling operations". Obtained the SOBRESALIENTE CUM LAUDE qualification.

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• Title of the thesis: "Cutting forces prediction in orthogonal turn-milling operations".
• Court:
  • President: Dr. Manuel San Juan Blanco (Universidad de Valladolid)
  • Vocal: Dr. Anders Liljerehn (AB Sandvik Coromant R&D)
  • Vocal: Dr. Juan Pablo Casas Rodríguez (Universidad de los Andes)
  • Vocal: Dr. Miguel Arizmendi Jaca (Universidad de Navarra-Tecnun)
  • Secretary: Dr. Mikel Saez de Buruaga Echeandia (Mondragon Unibertsitatea)

Abstract

The development of more versatile machine tools is addressing the increased market demand for more complex shapes and workpieces with strict tolerances. This has resulted in more complicated kinematics, designed to align the cutting tool with the intricate workpiece surface for its production. New machining operations supported in the advanced kinematics are emerging such as turn-milling operations, in which rotational movements of the workpiece are coupled with conventional milling operations. Turn-milling presents significant advantages over conventional turning: such as lower cutting forces, temperatures, circularity errors, and surface roughness. In addition, tool life is longer, and the operation generates intermittent chips which eliminates the continuous chip nests typical in turning. Despite these advantages however, turn-milling is difficult to operate in the optimal process window because it requires an increased number of process parameters, making their optional selection challenging. The prediction of process performance can be greatly enhanced by modeling, however traditional milling models do not consider turn-milling parameters evidencing the need for specific models for these operations. To address this gap, this thesis presents analytical and numerical models for orthogonal turn-milling operations to determine the uncut chip geometry and predict cutting forces. These models consider workpiece rotation, tool eccentricity, cutting tool profile, and the process kinematics in the accurate determination of the uncut chip geometry. The models were validated theoretically and experimentally presenting good correlation in each of the validation tests. The models were used to confirm the cutting conditions suggested by the cutting tool manufacturer in a real workpiece manufacturing plan. The engineered cutting conditions showed a reduction of 20\% in the overall manufacturing time. Additionally, the cutting edges were used more efficiently decreasing the number of inserts needed to finish the part, which in turn reduced the total manufacturing cost.