TY - JOUR

T1 - Powder ageing of Polyamide 6 in laser sintering and its effects on powder and component characteristics

AU - Stiller, Tanja

AU - Berer, Michael

AU - Katta, A. D.Kashyap

AU - Haar, Bernd

AU - Truszkiewicz, Eliza

AU - Kraschitzer, Wolfgang

AU - Stepanvosky, H.

AU - Pinter, Gerald Gerhard

AU - Lackner, Jürgen Markus

N1 - Funding Information: The research work of this paper was performed at the Polymer Competence Center Leoben GmbH (PCCL, Austria) within the framework of the funding program “Production of the Future” of the Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology and the Federal Ministry for Digital and Economic Affairs with contributions by Joanneum Research Forschungsgesellschaft mbH, Materials Science and Testing of Plastics / Montanuniversitaet Leoben , RPD Rapid Product Development GmbH and LSS Laser Sinterservice GmbH . The PCCL is funded by the Austrian Government and the State Governments of Styria , Lower Austria and Upper Austria. Publisher Copyright: © 2022 The Authors

PY - 2022/10

Y1 - 2022/10

N2 - The increasing importance of Laser Sintering (LS) for the industry brings a rising number of available materials for this process. One example is the enhanced use of alternative polyamide types like polyamide 6 (PA 6). For polyamide 12 (PA 12), the powder ageing effect is well-known and of great importance from an economical point of view. However, relatively little is known about the powder ageing behavior of newer LS materials. Hence this paper focuses on the experimental powder ageing study of PA 6 in the LS process, both on powder and part level. The powder was reused in total seven times without refreshing and constant sinter parameters were used to produce the samples. Morphological, thermal and rheological measurements of the powder showed a rising number of agglomerates, an apparent increase in the powder crystallinity, and an increase in the viscosity by a factor of 7. These increases consequently affected the density and the mechanical properties of the parts, latter were determined by tensile tests. Between the first and the last iteration, a decrease of the Young's Modulus of 60 % and the tensile strength of 70 % was observed. Besides the decline of mechanical properties, the geometrical dimensions of the last iteration were only 60 % of the first iteration, the mass was halved and the surface quality suffered from the orange peel effect. The results prove that similar powder ageing effects known for PA 12, and here especially the polyamide post condensation, also take place in LS printing of PA 6.

AB - The increasing importance of Laser Sintering (LS) for the industry brings a rising number of available materials for this process. One example is the enhanced use of alternative polyamide types like polyamide 6 (PA 6). For polyamide 12 (PA 12), the powder ageing effect is well-known and of great importance from an economical point of view. However, relatively little is known about the powder ageing behavior of newer LS materials. Hence this paper focuses on the experimental powder ageing study of PA 6 in the LS process, both on powder and part level. The powder was reused in total seven times without refreshing and constant sinter parameters were used to produce the samples. Morphological, thermal and rheological measurements of the powder showed a rising number of agglomerates, an apparent increase in the powder crystallinity, and an increase in the viscosity by a factor of 7. These increases consequently affected the density and the mechanical properties of the parts, latter were determined by tensile tests. Between the first and the last iteration, a decrease of the Young's Modulus of 60 % and the tensile strength of 70 % was observed. Besides the decline of mechanical properties, the geometrical dimensions of the last iteration were only 60 % of the first iteration, the mass was halved and the surface quality suffered from the orange peel effect. The results prove that similar powder ageing effects known for PA 12, and here especially the polyamide post condensation, also take place in LS printing of PA 6.

KW - Additive manufacturing

KW - Laser sintering

KW - Polyamide 6

KW - Polymer

KW - Powder ageing

UR - http://www.scopus.com/inward/record.url?scp=85132833195&partnerID=8YFLogxK

U2 - 10.1016/j.addma.2022.102987

DO - 10.1016/j.addma.2022.102987

M3 - Article

AN - SCOPUS:85132833195

VL - 58.2022

JO - Additive Manufacturing

JF - Additive Manufacturing

SN - 2214-8604

IS - October

M1 - 102987

ER -