Residual Stress Due to Finish Facing Comparing Traditional and Modulated Tool Path Machining Processes
1 online resource (136 pages) : PDF
University of North Carolina at Charlotte
TRAVIS ANDERSON. Residual stress due to finish facing comparing traditional and modulated tool path machining processes. (Under the direction of DR. ROD HANDY.) Traditional machining processes, where material is removed by a cutting tool from a workpiece, can introduce changes in the state of stress of a component at the machined surface. Knowledge of these changes is important for determining if the component is suitable for service. Changes to the machining process, such as feed rates, surface speeds, and tooling geometry can be used to mitigate these effects. This study examined the effects of a modulated tooling path, used to control chip geometry, on the surface stress of selected materials. Residual stress in machined samples was determined using X-Ray Diffraction (XRD), by comparing the modulated path method with a more traditional material removal (i.e., constant surface speed and constant contact) methodology. Utilizing a small computer numerically controlled (CNC) tool lathe, the cutting insert was programmed to run different tool paths to determine how much the machining process contributes to the stress in the machined material. Related researches included analyses of different tool paths to study tool wear and tool cutting forces. This research looked more specifically at the material’s response to different machining processes. Residual stress was measured by the use of a PANalytical® X’Pert Pro MRD™—referred to as an X-Ray Diffraction (XRD) machine in this report—and PANalytical’s proprietary "Stress™" software.Results from stress analyses were listed in table form and plotted for comparison purposes. Analysis of preliminary studies suggested that there is a standard range of stress levels based on turning process relevant to material type. Moreover, the aspect of preventing chips from becoming entangled around the cutting tool could be a desired benefit in the areas of safety and economics.A series of discontinuous cuts was programmed as a modulated tool path referred to as a modulated tool path process. Using the programmed modulated tool path process reduced chip length for all materials used in this experiment. Maximum chip length for the modulated tool path process was less than two inches. Furthermore, the x-ray diffraction process provided a method to non-destructively analyze the residual stress left by the different processes. Stress measurements analyzed indicated that different alloys of metals may respond uniquely to the turning process used. Aluminum 6061-T6 and tantalum 97Ta3W showed more of a trend in residual stress as the result of the different turning processes than the Inconel® 718 alloy.Therefore, the comparison of traditional turning and modulated tool path processes could yield varied results for different metal alloys. This project had trends in d-spacing analysis for the aluminum 6061-T6 and tantalum 97Ta3W; however, the Inconel® 718 did not yield a noticeable trend. Options for further development of this research would be to increase the sample population for better statistical analysis. Also, for alloys like Inconel® 718, altering the modulated tool path process could yield more consistent results. Some of the control variables that could be altered would include depth of cut in the X- or Z-axis, cutting speed, or insert used. Data that was gathered for this project revealed that better statistical analysis could have been achieved if there were more experiments for each sample. With more data, the relation of the previous stress might have been used to determine how the previous stress affected the residual stress resulting from each turning process type.
Applied Energy & Electromechanical System
Schmidt, PeterWilliams, WesleyMorrell, Jonathan
Thesis (M.S.)--University of North Carolina at Charlotte, 2015.
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). For additional information, see http://rightsstatements.org/page/InC/1.0/.
Copyright is held by the author unless otherwise indicated.