Correlation of reuse extent with degradation degree of PA 12 powder during laser powder bed fusion and mechanical behavior of sintered parts

• Published in: Polymer engineering and science 2023-01, Vol.63 (1), p.126-138
• Main Authors: Alo, Oluwaseun A., Otunniyi, Iyiola O., Mauchline, David
• Format: Article
• Language: English
• Subjects: Crystallites; Crystallization; Degradation; dynamic mechanical properties; Flow velocity; laser‐based powder bed fusion; Mechanical properties; melt flow rate; Melt temperature; Melting; Methods; polyamide 12; Polyamide resins; Polyamides; Polymers; Powder beds; Powders; Production processes; Quality control; Rapid prototyping; Sintering; Sintering (powder metallurgy); Thermal properties
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.26191

The development of an effective powder utilization is key to maximizing the potential of polyamide 12 (PA 12) for commercial laser‐based powder bed fusion of polymers (PBF‐LB/P). This requires an extensive study of relationships between the powder reuse extent, macroscopic properties of the powder, and mechanical properties of sintered parts. This work investigates the effects of the extent of PA 12 powder reuse during PBF‐LB/P on the powder's degradation degree and mechanical properties of the sintered parts. Powder reuse extent was expressed in terms of cumulative build time while degradation degree was assessed in terms of deviations in the properties of the reused powders from those of virgin powder. Increase in the powder reuse extent led to increased thickness of crystallite, melting temperature, and sintering window of the powder while the crystallization temperature, crystallinity degree, and melt flow rate decreased with increased reuse extent. The mechanical strength and modulus of the sintered parts initially decreased with an increase in number of build cycles to reach a minimum at the sixth build cycle, after which it increased. This study is a step further towards achieving an efficient PA 12 powder management and a systematic control of quality of sintered parts. Effects of reuse during laser powder bed fusion on melt flow rate and thermal properties of PA 12 powder and mechanical properties of sintered parts.