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Published November 24, 2016 | Published + Supplemental Material
Journal Article Open

Castable Bulk Metallic Glass Strain Wave Gears: Towards Decreasing the Cost of High-Performance Robotics


The use of bulk metallic glasses (BMGs) as the flexspline in strain wave gears (SWGs), also known as harmonic drives, is presented. SWGs are unique, ultra-precision gearboxes that function through the elastic flexing of a thin-walled cup, called a flexspline. The current research demonstrates that BMGs can be cast at extremely low cost relative to machining and can be implemented into SWGs as an alternative to steel. This approach may significantly reduce the cost of SWGs, enabling lower-cost robotics. The attractive properties of BMGs, such as hardness, elastic limit and yield strength, may also be suitable for extreme environment applications in spacecraft.

Additional Information

© 2016 The Author(s). This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received: 24 August 2016; Accepted: 01 November 2016; Published online: 24 November 2016. The authors acknowledge financial support from NASA's Science Mission Directorate and Space Technology Mission Directorate through the Game Changing Development program under Prime Contract #NAS7-03001 and from NASA's Center Innovation Funds. D.C. Hofmann also acknowledges support from the Presidential Early Career Award. Part of this research was done at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Patents related to the current technology have been filed with the California Institute of Technology. The authors acknowledge the commercial partners in this program, primarily Ryan Coniam and Shawn Armstrong, Visser Precision, Denver, CO, and Nicholas Hutchinson, Materion, Elmore OH. Author Contributions: D.C.H. wrote the manuscript, performed sample fabrication and designed the alloys. R.P.-C. created the model of the gear. S.N.R. performed sample fabrication and ran gear tests. J.-P.B. designed and manufactured the molds and prototypes. R.P.D. assisted with the design of the experiments and the alloy selection. E.H. designed, constructed and performed life testing. J.K. assisted in the sample fabrication and in the alloy characterization. L.M. performed optical microscopy. J.S. performed optical microscopy and did X-ray diffraction. A.H. performed DSC. K.C. integrated the gears into the robot and performed testing. A.P. assisted in the implementation in robotics and provided technical data on robotics gears. W.L.J. edited the manuscript and provided scientific guidance, A.K. assisted in the implementation of the gearboxes. B.W. devised the research and provided technical assistance on the gearboxes. The authors declare no competing financial interests.

Attached Files

Published - srep37773.pdf

Supplemental Material - srep37773-s1.pdf

Supplemental Material - srep37773-s10.avi

Supplemental Material - srep37773-s11.avi

Supplemental Material - srep37773-s2.mov

Supplemental Material - srep37773-s3.avi

Supplemental Material - srep37773-s4.avi

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Supplemental Material - srep37773-s8.avi

Supplemental Material - srep37773-s9.avi


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