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Cyclic Scheduling of Post Production Heat Treatment for Residual Stress Removal in Additive Manufactured Ti-6Al-4V

Webber, Trevor B
http://orcid.org/0000-0003-1289-039X
http://rave.ohiolink.edu/etdc/view?acc_num=osu1606732201282829

Abstract Details

2020, Master of Science, Ohio State University, Industrial and Systems Engineering.
Additive manufacturing, or 3-D printing, is becoming a pervasive manufacturing technique due to its flexibility and reliability. The incremental printing of 3-D objects allows parts to be prepared with more flexibility and precision than older manufacturing techniques like casting, forging, etc. The opportunities with 3-D printing are endless and are already being used in the Department of Defense, medical field, and aeronautics to name a few. With the increased flexibility and ability to manufacture complex geometries, challenging process science, control, and scheduling issues arise. Additive manufactured parts are susceptible to defects throughout the manufacturing process, specifically during the pre-processing, printing and post-processing of the parts, and the development of internal residual stress in the parts is of particular focus in this work. In order to minimize the residual stress after builds, parts are placed in a furnace to initiate stress relaxation. However, this process is currently being accomplished in small batches due to the current limited volume of AM produced parts. As this technology scales, optimization of these post-processing steps will become vital for increasing throughput and enabling the appropriate scale-up of the technology. In anticipation of the scale-up of AM technologies, the objective of this thesis is to investigate an optimal schedule for the stress relaxation process in various scenarios and determine which of these scenarios is optimal. We introduce a physics-based ii scheduling optimization framework through nonlinear mixed integer programming for toggling parts’ heating and cooling stages. We analyze different strategies to include modifying time steps a part is in and out of the furnace, introducing an insulated holding area, modifying the number of parts per batch, and changing our objective function. We will then compare the results to the legacy process that is used in order to determine what strategy is the most productive. The results reveal that the number and length of cycles used, the existence and intensity of an insulated holding area, and the number of parts per batch are statistically significant contributors to the completion time per part we are trying to optimize. Ultimately, the most important factor is the use of an insulated holding area. Once that is determined, we can evaluate the impact that decision has on different cycle lengths and batch sizes. The impact of the results, ideas for future research, and overall recommendations are discussed.
Michael Groeber (Advisor)
Andrew Gillman (Advisor)
90 p.
Operations Research
Cyclic Scheduling; Additive Manufacturing; Heat Treatment; Ti-6Al-4V;

Recommended Citations

Citations

  • Webber, T. B. (2020). Cyclic Scheduling of Post Production Heat Treatment for Residual Stress Removal in Additive Manufactured Ti-6Al-4V [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606732201282829

    APA Style (7th edition)

  • Webber, Trevor. Cyclic Scheduling of Post Production Heat Treatment for Residual Stress Removal in Additive Manufactured Ti-6Al-4V. 2020. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1606732201282829.

    MLA Style (8th edition)

  • Webber, Trevor. "Cyclic Scheduling of Post Production Heat Treatment for Residual Stress Removal in Additive Manufactured Ti-6Al-4V." Master's thesis, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606732201282829

    Chicago Manual of Style (17th edition)

osu1606732201282829
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This open access ETD is published by The Ohio State University and OhioLINK.
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