Continuous reuse of polyamide 12 in Powder Bed Fusion

The thermal degradation of polymers in powder bed fusion (PBF, additive manufacturing) is one of the major issues preventing wider adoption of this technology at the production scale. Although standard PBF allows for elastic production of complex parts in a single-step manufacturing process, it is materially inefficient – only approximately 10% of the material is used, with the majority of semicrystalline polyamide 12 (PA12) remaining in the form of free-flowing powder. Because the rest of the material remains below the melting point for a long time, it cannot be directly reused in subsequent processes. In this work, we present a novel way to process PA12 at room temperature without exposure to a thermal agent. Dual beam laser sintering (DBLS) uses a double laser system that effectively compensates for the temperature in the melting zone and prevents material shrinkage. To demonstrate the effectiveness of the DBLS method, the material was kept in a closed loop. Specimens from each iteration of the process ( n  = 4) were analyzed. No significant changes were observed in the chemical properties (molecular weight and melt viscosity, assessed via gel permeation chromatography (GPC) and melt flow index (MFI) analysis) or technological properties (flowability) of the powder samples or in the mechanical properties of the built specimens compared with the initial values.