On the effect of irradiance on dimensional accuracy in multijet fusion additive manufacturing

Abstract

Purpose The amount of radiated energy is known to be a crucial parameter in powder-bed additive manufacturing (AM) processes. The role of irradiance in the multijet fusion (MJF) process has not been addressed by any previous research, despite the key role of this process in the AM industry. The aim of this paper is to explore the relationship between irradiance and dimensional accuracy in MJF. Design/methodology/approach An experimental activity was carried out to map the relationship between irradiance and dimensional accuracy in the MJF transformation of polyamide 12. Two specimens were used to measure the dimensional accuracy on medium and small sizes. The experiment was run using six different levels of irradiance. For each, the crystallinity degree and part density were measured. Findings Irradiance was found to be directly proportional to part density and inversely proportional to crystallinity degree. Higher irradiance leads to an increase in the measured dimensions of parts. This highlights a predominant role of the crystallisation degree and uncontrolled peripherical sintering, in line with the previous literature on other powder-bed AM processes. The results demonstrate that different trends can be observed according to the range of sizes.

Selective Laser Sintering versus Multi Jet Fusion: A Comprehensive Comparison Study Based on the Properties of Glass Beads‐Reinforced Polyamide 12

“…[ 9,26 ] However, whether SLS or MJF gives higher part density is still controversial in the literature since it may also depend on the process parameters adopted to produce the parts (i.e., laser power, scan speed, and scan spacing for SLS and print profile and lamps irradiance for MJF), that are strictly confidential for MJF. [ 25,32,33 ] For example, Xu et al [ 10 ] found a lower amount of porosity in neat PA12 samples produced by SLS, while Abbott et al [ 16 ] got the opposite results; other authors [ 25,26 ] reported similar values for both techniques.…”

“…[29,30,32] However, details about the process parameters (e.g., lamps irradiance and speed) are not revealed by HP for intellectual property reasons. [25,33] The layer height was set at 80 μm, as recommended by the printer manufacturer.…”