The continuous improvements in micro-forging technologies generally involve process,\nmaterial, and tool design. The field assisted sintering technique (FAST) is a process that makes\npossible the manufacture of near-net-shape components in a closed-die setup. However, the final part\nquality is affected by the influence of friction during the ejection phase, caused by radial expansion\nof the compacted and sintered powder. This paper presents the development of a pre-stressed tool\nsystem for the manufacture of micro gears made of aluminum. By using the hot isostatic pressing\n(HIP) sintering process and different combinations of process parameters, the designed tool system\nwas compared to a similar tool system designed without a pre-stressing strategy. The comparison\nbetween the two tool systems was based on the ejection force and part fidelity. The ejection force was\nmeasured during the tests, while the part fidelity was documented using an optical microscope and\ncomputed tomography in order to obtain a multi-scale characterization. The results showed that the\nuse of pre-stress reduced the porosity in the gear by 40% and improved the dimensional fidelity by\nmore than 75% compared to gears produced without pre-stress.
Loading....