Additive manufacturing by material extrusion (MEX) of highly filled polymers shows significant potential for prototyping and rapid manufacturing of complex geometry metallic components. However, a major challenge of this process lies in eliminating the rhomboid voids at the intersection of the four extruded material strands, which present an oblong shape. The size and arrangement of these voids, which limit the achievable green density by this technique, are primarily influenced by the deposition method. To address this challenge, a study on the impact of certain extrusion parameters (layer height, extrusion speed, nozzle temperature, and bed temperature) was conducted to determine the optimal operational range of a new 3D printer using the piston principle to fabricate parts with a stainless-steel powder feedstock (17-4PH). A thorough investigation into the impact of different deposition approaches was then carried out to analyze the influence of printing parameters on the dimensional properties and density of the produced parts. The results showed that by using first bead overlap strategy (with a 20% overlap rate), it was possible to eliminate interlayer rhomboid voids while minimizing dimensional deviations of parts manufactured by MEX. Additionally, it was found that certain strategies, such as the flow multiplier, although popular, could lead to significant dimensional deviations from the nominal value. These deviations are mainly due to material over-extrusion and the significant pressure caused by this strategy in the print head. It was also demonstrated that the first bead overlap strategy, when applied at a 20% level, enabled the production of parts with a maximum dimensional variation limited to 50 μm, without compromising density. This conclusion confirms that this new approach is superior for producing defect-free parts with minimal dimensional variation. These results are of great importance for improving the quality and precision of metallic parts produced by MEX, thus paving the way for new opportunities in various industrial sectors.
| Date | 4 Jun 2024 |
|---|
| Original language | French |
|---|
| Awarding Institution | - École de technologie supérieure
|
|---|
| Supervisor | Vincent Demers (Supervisor), Jérémie Soulestin (Supervisor) & Nicole R. Demarquette (Co-supervisor) |
|---|
Côté, R. (Author),
Demers, V. (Supervisor), Soulestin, J. (Supervisor) &
Demarquette, N. R. (Co-supervisor),
4 Jun 2024Student thesis: Doctoral thesis › Doctorate in Engineering: Engineering