Daniel Iwao Suyama

Evaluating the use of high-pressure coolant in turning process of Inconel 625 nickel-based alloy

The automotive, aerospace and energy industries have lately increased their search for materials which must have high mechanical resistance/weight ratio and capability to maintain the mechanical properties in high temperatures and at corrosive environments in order to produce critical parts of their equipment. The nickel-based alloys are one type of materials which have been a good answer for this search. On the other hand, the very good mechanical properties of these alloys make their manufacturing very difficult, especially when machining processes are used. Among other problems in the machining of these alloys, due to the high mechanical resistance in high temperature, tool lives used to be much shorter than when steel alloys are machined, forcing cutting speeds to be much lower and, consequently, to have less productive processes. The main goal of this work was to test an alternative to increase tool life in the turning of Inconel 625 nickel-based alloy by the use of high-pressure coolant. This system was tested using different directions of the fluid flow (toward the rake face, toward the flank face and directing the fluid simultaneously toward these two tool faces) compared to the conventional way of applying fluid. The results show that the use of high-pressure coolant harms the notch wear development and, consequently, increases tool life with simultaneous improvement of workpiece surface roughness in some cases. However, the application of high-pressure coolant over both flank and rake faces at the same time did not provide any improvement.

Modeling and Simulation of the Drivetrain of a Metal Lathe

Vibrations in turning machining are one of the most common sources of problems. Bad quality finishing, decrease of the tool life, dimensional errors, and noise are some of the issues generated by these vibrations. To understand the role of each component, this work presents a model of a metal lathe including its drivetrain, and simulates it during the internal turning operation. The drivetrain is composed by an electric motor connected to the spindle through a pulley and belt transmission. The spindle was modeled as a rotor supported by rolling bearings, while the chuck with jaws and the workpiece were considered to be rigidly attached to the spindle. The interface between the workpiece and the tool was modeled considering their relative displacement and the machining condition, thus generating a set of cutting and drag forces that varies during the operation. The tool holder was modeled by three-node finite volume beam elements that are attached to the turret. The turret was connected to the machine frame through a total joint (configured as prismatic). This model was implemented in the dynamic simulation software MBDyn and a module was developed in C++ to mimic the interaction between workpiece and tool. Different configurations of the machine were tested, such as the diameter of the tool holder and the rotation speed of the spindle, and their influence on the drivetrain is reported.