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Micromachines 2017, 8(7), 214; doi:10.3390/mi8070214

Designing a Tool System for Lowering Friction during the Ejection of In-Die Sintered Micro Gears

1
IPU Product Development, Kgs. Lyngby, 2800 DK, Denmark
2
DTU Department of Mechanical Engineering, Kgs. Lyngby, 2800 DK, Denmark
3
DTU Department of Electrical Engineering, Kgs. Lyngby, 2800 DK, Denmark
*
Author to whom correspondence should be addressed.
Received: 29 May 2017 / Revised: 30 June 2017 / Accepted: 3 July 2017 / Published: 6 July 2017
(This article belongs to the Special Issue Micro/Nano Manufacturing)
View Full-Text   |   Download PDF [8606 KB, uploaded 6 July 2017]   |  

Abstract

The continuous improvements in micro-forging technologies generally involve process, material, and tool design. The field assisted sintering technique (FAST) is a process that makes possible the manufacture of near-net-shape components in a closed-die setup. However, the final part quality is affected by the influence of friction during the ejection phase, caused by radial expansion of the compacted and sintered powder. This paper presents the development of a pre-stressed tool system for the manufacture of micro gears made of aluminum. By using the hot isostatic pressing (HIP) sintering process and different combinations of process parameters, the designed tool system was compared to a similar tool system designed without a pre-stressing strategy. The comparison between the two tool systems was based on the ejection force and part fidelity. The ejection force was measured during the tests, while the part fidelity was documented using an optical microscope and computed tomography in order to obtain a multi-scale characterization. The results showed that the use of pre-stress reduced the porosity in the gear by 40% and improved the dimensional fidelity by more than 75% compared to gears produced without pre-stress. View Full-Text
Keywords: micro sintering; field assisted sintering technique; hot isostatic pressing; micro gears; computed tomography; dimensional accuracy; porosity analysis micro sintering; field assisted sintering technique; hot isostatic pressing; micro gears; computed tomography; dimensional accuracy; porosity analysis
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Cannella, E.; Nielsen, E.K.; Stolfi, A. Designing a Tool System for Lowering Friction during the Ejection of In-Die Sintered Micro Gears. Micromachines 2017, 8, 214.

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