ABSTRACT Polylactic acid (PLA) material in filament form can be 3D printed and form complex physical models by using a low-cost material extrusion mechanism in a process that is broadly known as fused filament fabrication (FFF). Even though the PLA-FFF process has been extensively studied in the literature, its parts’ mechanical response varies significantly, and it has not been studied in association with six control parameters at the same time, i.e. the infill density (ID), raster deposition angle (RDA), nozzle temperature (NT), printing speed (PS), layer thickness (LT), and bed temperature (BT). The simultaneous influence of the variable parameters on the mechanical properties is a challenging assignment and aspires to rank the six parameters’ importance, model the process, and finally validate the models by using independent experiments. One-hundred twenty-five experiments run following the Taguchi L25 orthogonal array repeated five times for the study purpose. After an extensive literature survey and preliminary experiments, the parameter selection and discrete values were selected. The experimental results were analyzed using statistical tools and critically compared with that of the literature. The RDA, NT, PS, and ID significantly impact the mechanical response of the 3D printed PLA parts.

A multi-parametric process evaluation of the mechanical response of PLA in FFF 3D printing

The latest developments in smart systems for improved human lives with advanced biomedical devices have evolved out of multi-disciplinary scientific studies, including medicine, biology, material sciences, design, manufacturing, artificial intelligence, microelectronics, and so forth. The growth of such intelligent systems is primarily possible with innovative materials, which demonstrate the response to various external stimuli like temperature, heat, moisture, light, electromagnetic field, and chemical alteration. Such materials have been recently fabricated using different additive manufacturing techniques to devise personalized unique, complex, and novel structures that can adjust to external conditions over time and are specifically attributed to 4D printing. Novel materials that can further improve such systems continued to be explored and employed. This review paper investigates the additive manufacturing of functional polymer nanocomposites, which offer compliant structures with flexible manufacturing processes with high strength, low cost, and long-term stability. This study aims to deliver a comprehensive and deep understanding of the latest developments in materials, design, manufacturing, fundamental mechanisms involved, and future possibilities in this area of research. 

Additive manufacturing of smart polymeric composites: Literature review and future perspectives

ABSTRACT Energy metrics in 3D-printing technologies are of major importance for sustainable manufacturing. The printing parameters (PP) affect the energy consumption remarkably and define the overall Energy Printing Consumption (EPC), the Specific Printing Energy (SPE), and Specific Printing Power (SPP). This study investigates the impact of six PPs: the infill raster density (ID), raster deposition angle (RDA), nozzle temperature (NT), fused filament printing speed (PS), layer deposition thickness (LT), and bed temperature (BT), on the above three energy indexes, i.e. the EPC, SPE, and SPP. The experimental course follows the Taguchi L25 orthogonal array (OA) with six repetitions. The experimental data were dissolved and studied utilizing descriptive statistical tools, i.e. main effect plots (MEP plots), ANOVA, and response surface methodology (RSM). Six evaluation experiments validated the extracted quadratic regression models (QRM). The above statistical models thoroughly describe the effects of six intended fused filament fabrication (FFF) printing parameters on the energy metrics (EPC, SPE, and SPP). Additionally, the physical mechanism is explained in depth by applying mechanical strength evaluation tests for all ranges of parameters’ values. This study proposes a methodology for efficient and sustainable FFF.

The effects of FFF 3D printing parameters on energy consumption

In this work, we present an effective process easily adapted in industrial environments for the development of multifunctional nanocomposites for material extrusion (MEX) 3D printing (3DP). The literature is still very limited in this field, although the interest in such materials is constantly increasing. Nanocomposites with binary inclusions were prepared and investigated in this study. Polylactic acid (PLA) was used as the matrix material, and cuprous oxide (Cu2O) and cellulose nanofibers (CNF) were used as nanoadditives introduced in the matrix material to enhance the mechanical properties and induce antibacterial performance. Specimens were built according to international standards with a thermomechanical process. Tensile, flexural, impact, and microhardness tests were conducted. The effect on the thermal properties of the matrix material was investigated through thermogravimetric analysis, and Raman spectroscopic analysis was conducted. The morphological characteristics were evaluated with atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDS) analyses. The antibacterial performance of the prepared nanomaterials was studied against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria, with a screening agar well diffusion method. All nanocomposites prepared exhibited biocidal properties against the bacteria tested. The tested PLA/1.0 CNF/0.5 Cu2O material had 51.1% higher tensile strength and 35.9% higher flexural strength than the pure PLA material.

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Multifunctional Material Extrusion 3D-Printed Antibacterial Polylactic Acid (PLA) with Binary Inclusions: The Effect of Cuprous Oxide and Cellulose Nanofibers

Many concerns are being expressed about the biodegradability, biocompatibility, and long-term viability of polymer-based substances. This prompted the quest for an alternative source of material that could be utilized for various purposes. Starch is widely used as a thickener, emulsifier, and binder in many food and non-food sectors, but research focuses on increasing its application beyond these areas. Due to its biodegradability, low cost, renewability, and abundance, starch is considered a “green path” raw material for generating porous substances such as aerogels, biofoams, and bioplastics, which have sparked an academic interest. Existing research has focused on strategies for developing biomaterials from organic polymers (e.g., cellulose), but there has been little research on its polysaccharide counterpart (starch). This review paper highlighted the structure of starch, the context of amylose and amylopectin, and the extraction and modification of starch with their processes and limitations. Moreover, this paper describes nanofillers, intelligent pH-sensitive films, biofoams, aerogels of various types, bioplastics, and their precursors, including drying and manufacturing. The perspectives reveal the great potential of starch-based biomaterials in food, pharmaceuticals, biomedicine, and non-food applications.

/pdf/valorization-of-starch-to-biobased-materials-a-review-3bgl3tz3.pdf

Valorization of Starch to Biobased Materials: A Review

ABSTRACT Fused filament fabrication (FFF) is an additive manufacturing process, which constructs physical items by fused melt material, selectively deposited layer-by-layer through a heated extrusion mechanism. Parameters’ selection and control in FFF are of utmost importance since they significantly affect the surface quality (SQ) and dimensional accuracy (DA) of the FFF printed parts. In the present paper, initially, the FFF process is briefly presented. Next, a cause-and-effect diagram exhibits the process parameters’ categorization with the SQ and DA of the manufactured parts. Then, according to the robust design theory, the process parameters are divided into three classes, i.e., the signal, the control, and the noise. This classification supports the selection of appropriate FFF printers, according to the control parameters, whereas it facilitates the optimization of the SQ and DA of printed parts, concerning the signal parameters. Finally, the impact of each parameter on SQ and DA is presented, supported by an extensive literature review. Overall, the process parameters’ optimization is critical for the SQ and DA. Therefore, they should be adjusted to achieve higher quality and less post-processing work.

Key parameters controlling surface quality and dimensional accuracy: a critical review of FFF process

ABSTRACT Polyamide 12 (PA12) is a high-performance polymeric material adopted by various industries for its thermal, electrical, and mechanical properties. In this work, a comprehensive examination of the impact of three 3D printing (3DP) parameters, i.e., Nozzle Temperature (NT), Layer Height (LH), and raster Deposition Angle (DA), on the mechanical strength and toughness of Fused Filament Fabrication (FFF) 3DP PA12 polymer is studied. The general full factorial experimental methodology is followed. The 3DP parameters’ effects were analyzed using descriptive and analytic statistical tools, such as Box plots, interaction charts, and ANOVA analysis. The experimental data depicted different spreads and median values for each parameter level regarding the utilized responses, concluding that the modeling process is vital for the process control and the parameters’ optimization. Two predictive models, a Quadratic Regression Model (QRM) and an Artificial Neural Network (ANN) are fitted on the median values of the experimental data responses predictions, i.e. static mechanical strength (σb), elastic modulus (E), and toughness (T). The ANN performance was proven to be better than the QRM, providing better Mean Absolute Percentage Error (MAPE) values. NT and LH increase σb and T medians and spreads, while zero raster DA optimizes the σb and T.

J. Kechagias

Papers

Key parameters controlling surface quality and dimensional accuracy: a critical review of FFF process

Parameter effects and process modelling of Polyamide 12 3D-printed parts strength and toughness

A multi-parametric process evaluation of the mechanical response of PLA in FFF 3D printing

Multi-parameter optimization of PLA/Coconut wood compound for Fused Filament Fabrication using Robust Design

A comprehensive investigation of the 3D printing parameters’ effects on the mechanical response of polycarbonate in fused filament fabrication