Exploration of hardness variations for additive manufactured thin-walled components built by multi-axis tool paths


Using multi-axis tool paths in combination with a structured segmentation strategy introduces novel fabrication solutions for the direct energy deposition additive manufacturing process. However, with a piecemeal manufacturing strategy, interface regions are introduced. The goal of this research is to determine whether utilizing a multi-stage, multi-axis build strategy has an impact on the resulting hardness characteristics within the component. Surface roughness variations are noticeable when using a partitioning approach, so it is expected that hardness variations will result. The case studies consist of fabricating a set of thin wall (2 mm) hemispheres or domes. Two 45-mm nominal diameter domes are built using a wedge-based partitioning strategy. A 60-mm-diameter dome is fabricated using a rotary tool path approach. Various data collection strategies are investigated, and 300 gf or 1000 gf is recommended for the setup. It is found that the hardness across the bead thickness does not vary greatly at any point, but the hardness varies along the thin wall as the bead builds up. The interface zones have distinctly different hardness values, and the pattern is repeatable. Using fast Fourier transforms, the frequency of the noticeable surface roughness and hardness variation aligns to the interface boundary regions. This experiment illustrates that novel build solutions can be employed to eliminate the necessity of supports, but resolving a geometry issue may introduce physical and mechanical property variations within a component.

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This research is partially funded by the MITACs Accelerate Internship program. Special thanks to CAMUFACTURING Solutions, Inc. especially the president Bob Hedrick for partial funding, technical support and use of their APLUS software to create the toolpaths. Also, Thanks to Lincoln laser Solutions for sharing their facilities.


This research was funded by Mitacs Accelerate. Award number: IT12867. Grant recipients: Dr. Jill Urbanic, Dr. Mehrdad Saif

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HK: Design of the experiments, data collection and analysis, paper write up.

RJU: Data analysis, paper write up, project support

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Correspondence to Jill Urbanic.

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The manuscript is not submitted to any other journal simultaneously. The manuscript will not be submitted elsewhere until the editorial process is completed. The submitted work is original. A single study “Hardness Variations for Additive Manufactured Thin-Walled Components Built by Multi-Axis Tool Paths” is not be split up into several parts to increase the quantity of submissions. There is not any content being translated from other journals in other languages. Results are presented clearly, honestly, and without fabrication, falsification or inappropriate data manipulation. No data, text, or theories by others are presented as if they were the author’s own (“plagiarism”). The authors have permission to use the applied software. This research has not been applied to pose a threat to public health or national security.

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Kalami, H., Urbanic, J. Exploration of hardness variations for additive manufactured thin-walled components built by multi-axis tool paths. Int J Adv Manuf Technol 113, 2209–2226 (2021). https://doi.org/10.1007/s00170-021-06724-0

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  • Vickers microhardness
  • Directed energy deposition
  • Complex thin-wall geometry
  • Experimental data