Discrete element simulation and experimental study of powder spreading process in additive manufacturing

By Sina Haeri, Yuan Wang, O. Ghita, Jin Sun. 2017

309 citations recorded by the source corpus.

Powders used in additive manufacturing (AM) are spread into a compact layer of particles for sintering and this process is repeated layer by layer to form the final products. Spreading of rod-shaped particles in realistic AM settings is simulated using the discrete element method (DEM) to investigate the effects of particle shape and operating conditions on the bed quality, characterised by its surface roughness and solid volume fraction. It is discovered that larger particle aspect ratios, Ar, or higher spreader translational velocities result in a lower bed quality, i.e. a larger surface roughness and a smaller volume fraction. The surface roughness increases monotonically with Ar. However, the volume fraction exhibits a maximum at Ar = 1.5 for randomly packed powder beds that are formed by the roller type spreaders moving at low translational velocities. It is also found that a roller outperforms a blade spreader in terms of the quality of the prepared bed at the same operating conditions. The micro-structural analysis of the beds also shows particle alignment in response to the induced flow, which is qualitatively confirmed by a set of purposely-designed experiments. In addition, a shape segregation is documented for powders with mixed aspect ratios (Ar) such that particles with larger Ar tend to accumulate on the upper layers of the bed.

Subfields: Automotive Engineering, Computational Mechanics, Ocean Engineering

View Paper: https://www.semanticscholar.org/paper/58c80e62fcdb69aeabca7fa6382ebc767675a656

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In Automotive Engineering

1. T. Bonakdar
2. N. Azurmendi
3. A. Lores
4. M. Ghadiri
5. Alejandro López
6. Z. Pei
7. Chao Ma
8. Ming Li

In Computational Mechanics

1. T. Bonakdar
2. M. Ghadiri
3. Alejandro López
4. Z. Pei
5. Chao Ma
6. Ming Li
7. W. Du
8. Alaa H. Elwany

In Ocean Engineering

1. T. Bonakdar
2. M. Ghadiri
3. Alejandro López
4. Z. Pei
5. Chao Ma
6. Ming Li
7. W. Du
8. Alaa H. Elwany

Citations in the corpus

• A review on recent developments in binder jetting metal additive manufacturing: Materials and process characteristics (2019, background): “Counter-rotating function of the roller is to fl uidise the powder material, decreasing the shear forces in the previously processed layers and allowing better packing of powder particles [47,48].”
• Ceramic Binder Jetting Additive Manufacturing: A Literature Review on Density (2020, background): “In a numerical study, counter-rotating roller outperforms the doctor blade in achieving high powder bed density and low surface roughness [190].”
• Jamming during particle spreading in additive manufacturing (2018, methodology): “[22] investigated the effects of aspect ratio of rod-like particles and operation conditions on the bed quality.”
• Metal Binder Jetting Additive Manufacturing: A Literature Review (2020, methodology): “It is also known that the effects of spreader type and spreading strategy on powder bed are significant [152, 160].”
• Optimisation of blade type spreaders for powder bed preparation in Additive Manufacturing using DEM simulations (2017, unknown): “5 in this study [1] considering the angle of repose test results for different PEEK powders reported by Wang et al.”