Effect of the angle of the laid-up filaments on the surfaces on the coefficient of static friction between parts manufactured by extrusion-based 3D printing

Abstract

Three-dimensional printers, particularly the extrusion-based ones, are driving a global academic, industrial, and social revolution. The accessibility of the technology has allowed a number of enthusiasts and scientists to dedicate efforts to improve the technical properties of the parts produced. However, there is little literature on the measurement of the coefficient of friction, especially the static one, between a pair of printed parts. In this sense, an investigation was carried out in two stages, in which at first the static coefficient of friction was measured, through a simple apparatus based on the concept of the inclined plane, varying the angle of the filaments laid up on the surfaces of the two parts in contact. The parameter was analyzed at three levels—0°, 45°, and 90°—in components manufactured in poly(lactic acid) and poly(ethylene glycol terephthalate). In the second part of the research, a case study was carried out to test and validate the effects of the best and worst friction conditions on the behavior of the insertion force of snap-fit connections. The results obtained show a significant influence of the filament angle in the interaction between two printed parts. Combinations of contact with different angles decrease the static coefficient of friction, while faces with equal angles tend to increase the magnitude of the response, especially if the arrangement of the filaments allows a fit of the surfaces opposite to sliding. The static coefficient of friction of poly(lactic acid) varied from 0.12 to 0.38, while the static coefficient of friction of poly(ethylene glycol terephthalate) varied from 0.13 to 0.21. The responses of the inclined plane test allowed to predict the behavior of the insertion force and plan the design of quick fittings.

AltPrint: new filling and slicing process planning based on deposited material with geometry variation

“…The algorithm and the parameters developed in the design of flexible parts demonstrated an application for variable-width segments and three geometries, namely, snap-fit, ratchet mechanism and functional ratchet tool were defined and printed. Snap-fit mechanisms require controlled and predictable bending (Santana et al , 2021, 2017), characteristics that are in line with this study.…”

“…This section introduces the algorithm (Section 2.1), analyzes the material selected for the study (Section 2.2), the manufactured parts (Sections 2.3–2.5) and describes case studies (Section 2.6). The article proposes a new filling procedure based on a slicing algorithm validated according to three pillars of AM, namely, equipment, material and parameters (Santana et al , 2021). The analysis of the ABS filament and the choice of parameters for testing were important for the understanding of the flexible region generation and the way the code should be regulated for new users and FFF equipment.…”

Examining the surface quality of inner and outer surfaces in material extrusion printed samples

“…7 Despite the popularity of material extrusion, the technology still lacks the desired qualities of traditional manufacturing processes in aspects such as part quality, dimensional and geometric conformity, tolerances, surface finish, and mechanical properties. 8 Poor surface quality is one of the main drawbacks. Thus, the surface often requires postprocessing, 3 including chemical post-treatment and hot air jet, as demonstrated by Galantucci et al 9 and Adel et al, 10 respectively.…”