October_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | O C T O B E R 2 0 2 0 1 3 Fig. 1 — Top left, schematics of a filament extruder [12] ; top, microstructure engineering of filaments, (b1) polymer, and reinforced with (b2) low and (b3) high volume of particulate reinforcements; top right, FDM setup being fed customized filaments; bottom, illustration of morphology of printed samples at different levels, (d1) orientation (y direction is into the plane of the paper), (d2) printing layer thickness, (d3) width, air gap, and (d4) raster angle (θ) with reference to x-axis [9] . (d1) (d2) (d3) (d4) A s the rapidly growing global pop- ulation drives to improve their standard of living, the demand for energy, healthcare, housing, trans- portation, and industrial products is also increasing at unprecedented rates. To ad- dress future societal needs, newmaterials and sustainable development solutions such as the circular economy (CE) must be realized. CE envisions a newway to de- sign, make, and use resources [1] . Additive manufacturing (AM) has emerged as one of themost important technologies indis- rupting global supply chains and playing a critical role in sustainable development. This technology also potentially fits into the CE model, as it can incorporate re- cycled and reclaimed materials during manufacturing [2] . AM is defined by ASTM as “a process of joiningmaterials tomake objects from 3D model data, usually lay- er upon layer, as opposed to subtractive manufacturingmethodologies.” [3] Tremendous growth has occurred in the AM landscape with the introduc- tion of commercially available high-end reinforcements and processing param- eters on the tribological behavior of polymer matrix composites fabricat- ed by fused filament fabrication (FFF)- based 3D printing, also referred to as fused deposition modeling (FDM). FDM was invented by S. Scott Crump in 1988 and patented in 1989 [5] . FDM is the trademarked name of the process and is used interchangeably with FFF. ASTM F2792-12a defines this process as “a material extrusion pro- cess used to make thermoplastic parts through heated extrusion and deposi- tion of materials layer by layer” [3] . FFF entails the design of custom- ized filaments (Fig. 1), extrusion of fil- aments with a dimensional accuracy of 100 µm [6] by a nozzle, and design of a green body by depositing the fil- aments in a layer-by-layer sequence. This method is well-suited for manufac- turing polymers with filled particles like ceramics and metals. Excellent reviews have summarized the recent progress in FFF-based materials research [7-11] . 3D printingmachines suitable for indus- trial applications. In addition, the avail- ability of desktop 3D printers, as well as open-source printers and platforms, has facilitated large-scale growth of dis- tributed digital manufacturing. The par- adigm shift in thinking, where one can turn a design into product on demand, is leading to new business models— challenging traditional means of prod- uct development and distribution, as well as disrupting established global supply chains. In a recent review, Holmberg and Erdemir outlined that tribology-based processes can lead to approximately 23% (119 EJ) of the world’s total ener- gy consumption [4] . They further calcu- lated that 3% of this total corresponds to replacing worn out equipment, whereas 20% is consumed in overcom- ing frictional losses. Thus, the integra- tion of AM and triboactive materials in a single platform can lead to a nov- el design paradigm. In this brief review, we will explore the effect of particulate