Understanding pore formation and the effect on mechanical properties of High Speed Sintered polyamide-12 parts: A focus on energy input

• Published in: Materials & design Vol. 194; p. 108937
• Main Authors: Zhu, Zicheng, Majewski, Candice
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2020; Elsevier
• Subjects: Additive manufacturing; High speed sintering; Polyamide-12; Porosity; Powder bed fusion; X-ray computed tomography; Powder bed fusion; High speed sintering; Additive manufacturing; Porosity; Polyamide-12; X-ray computed tomography
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2020.108937

High Speed Sintering is a novel powder-bed fusion Additive Manufacturing technique that uses an infrared lamp to provide intensive thermal energy to sinter polymer powders. The amount of thermal energy is critical to particle coalescence related defects such as porosity. This study investigates the effect of energy input on porosity and the resulting mechanical properties of polyamide-12 parts. Samples were produced at different lamp speeds, generating varying amount of energy input from a low to a high level. They were then scanned using X-ray Computed Tomography technique, following which they were subject to tensile testing. A strong correlation between energy input, porosity and mechanical properties was found, whereby pore formation was fundamentally caused by insufficient energy input. A greater amount of energy input resulted in a reduced porosity level, which in turn led to improved mechanical properties. The porosity, ultimate tensile strength and elongation achieved were 0.58%, 42.4 MPa and 10.0%, respectively, by using the standard parameters. Further increasing the energy input resulted in the lowest porosity of 0.14% and the highest ultimate tensile strength and elongation of 44.4 MPa and 13.5%, respectively. Pore morphology, volume, number density and spatial distribution were investigated, which were found to be closely linked with energy input and mechanical properties. [Display omitted] •The effect of energy input on pore formation, porosity and resulting mechanical properties of High Speed Sintered parts was investigated.•Porosity, pore morphology, volume, number density and spatial distribution were examined using the X-ray Computed Tomography technique.•A strong correlation between energy input, porosity and mechanical properties was found.•Increasing energy input led to reduced porosity and improved mechanical properties, with pores that tended to be more spherical and distributed in sub-surface regions.•Decreasing energy input resulted increased porosity, causing large inter- and cross-layer pores to form, which were detrimental to mechanical properties.