This paper aims to investigate how the user-controlled parameters of the fused filament fabrication three-dimensional printing process define temperature conditions on the boundary between layers of the part being fabricated and how these conditions influence the structure and strength of the polylactic acid part.
Fracture load in a three-point bending test and calculated related stress were used as a measure. The samples were printed with the long side along the z-axis, thus, in the bend tests, the maximum stress occurred orthogonally to the layers. Temperature distribution on the sample surface during printing was monitored with a thermal imager. Sample mesostructure was analyzed using scanning electron microscopy. The influence of the extrusion temperature, the intensity of part cooling, the printing speed and the time between printing individual layers were considered.
It is shown that the optimization of the process parameters responsible for temperature conditions makes it possible to approximate the strength of the interlayer cohesion to the bulk material strength.
The novelty of the study consists in the generalization of the outcomes. All the parameters varied can be expressed through two factors, namely, the temperature of the previous layer and the extrusion efficiency, determining the ratio of the amount of extruded plastic to the calculated. A regression model was proposed that describes the effect of the two factors on the printed part strength. Along with interlayer bonding strength, these two factors determine the formation of the part mesostructure (the geometry of the boundaries between individual threads).
The authors express their gratitude to the reviewers, whose criticism and advices helped a lot in improvement of the manuscript clearness and readability.
Conflicts of Interest: The authors declare no conflict of interest.
Funding: This research was funded by the Ministry of Education and Science of the Russian Federation in the framework of increase Competitiveness Program of NUST “MISIS”, implemented by a governmental decree dated 16th of March 2013, No. 211.
Kuznetsov, V.E., Solonin, A.N., Tavitov, A., Urzhumtsev, O. and Vakulik, A. (2020), "Increasing strength of FFF three-dimensional printed parts by influencing on temperature-related parameters of the process", Rapid Prototyping Journal, Vol. 26 No. 1, pp. 107-121. https://doi.org/10.1108/RPJ-01-2019-0017
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