TY - GEN
T1 - Experimental and numerical investigations of the die filling of iron powders
AU - Ozaki, Y.
AU - Uenosono, S.
AU - Tagami, N.
AU - Kuwagi, K.
AU - Noda, R.
AU - Horio, M.
PY - 2006
Y1 - 2006
N2 - The flow rate is one of the most familiar indexes showing fluidity of powders. In commercial iron powders, it has been well known that a water atomized iron powder (WAIP) flows faster than a reduced iron powder (RIP). However, we found that the filling density of the WAIP in the narrow cavity was significantly lower as compared with that of the RIP. In this paper, we investigated the mechanisms that obstruct the die filling of the WAIP by focusing on the distinctions in the following powder characteristics: particle density, roughness on the particle surfaces, and contents of fine powder particles. The influences of these factors were examined by numerical and experimental procedures. We simulated the filling behaviors of mono-sized particles that had different particle densities based on discrete element method (DEM). The DEM simulations showed that the particle density did not have any influences. Furthermore, we examined the packing densities in the narrow die cavity for the sample powders: a WAIP having the rough particle-surfaces attached with fine iron particulates, and WAIPs sieved including various contents of fine particles smaller than 45 μm. The roughness on the particle-surfaces did not have any effect on the filling, but the reduction of fine powder content improved the incomplete filling especially in the narrow die cavity. To investigate the role of the fine powder, we measured powder yield loci (PYL) of the sample powders, and found that the share stress and the inner angle in the powder beds increased associated with the content of fine powder particles. These results indicate that the fine powder particles built the rigid powder structures that make it difficult for powder particles to be discharged from the shoe or to be packed in the die cavity. Therefore, the reduction of the content of the fine powder seems to be one of the most effective solutions to provide the homogeneous filling, and to reduce the variety in the green density of a complicated-shaped part.
AB - The flow rate is one of the most familiar indexes showing fluidity of powders. In commercial iron powders, it has been well known that a water atomized iron powder (WAIP) flows faster than a reduced iron powder (RIP). However, we found that the filling density of the WAIP in the narrow cavity was significantly lower as compared with that of the RIP. In this paper, we investigated the mechanisms that obstruct the die filling of the WAIP by focusing on the distinctions in the following powder characteristics: particle density, roughness on the particle surfaces, and contents of fine powder particles. The influences of these factors were examined by numerical and experimental procedures. We simulated the filling behaviors of mono-sized particles that had different particle densities based on discrete element method (DEM). The DEM simulations showed that the particle density did not have any influences. Furthermore, we examined the packing densities in the narrow die cavity for the sample powders: a WAIP having the rough particle-surfaces attached with fine iron particulates, and WAIPs sieved including various contents of fine particles smaller than 45 μm. The roughness on the particle-surfaces did not have any effect on the filling, but the reduction of fine powder content improved the incomplete filling especially in the narrow die cavity. To investigate the role of the fine powder, we measured powder yield loci (PYL) of the sample powders, and found that the share stress and the inner angle in the powder beds increased associated with the content of fine powder particles. These results indicate that the fine powder particles built the rigid powder structures that make it difficult for powder particles to be discharged from the shoe or to be packed in the die cavity. Therefore, the reduction of the content of the fine powder seems to be one of the most effective solutions to provide the homogeneous filling, and to reduce the variety in the green density of a complicated-shaped part.
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M3 - Conference contribution
AN - SCOPUS:84883379887
SN - 9780976205760
T3 - Advances in Powder Metallurgy and Particulate Materials - 2006, Proceedings of the 2006 International Conference on Powder Metallurgy and Particulate Materials, PowderMet 2006
SP - 335
EP - 346
BT - Advances in Powder Metallurgy and Particulate Materials - 2006, Proceedings of the 2006 International Conference on Powder Metallurgy and Particulate Materials, PowderMet 2006
T2 - 2006 International Conference on Powder Metallurgy and Particulate Materials, PowderMet 2006
Y2 - 18 June 2006 through 21 June 2006
ER -