Search Results (11)

A restorative process, where the nonmetallic fraction from e-waste printed circuit boards is reused as a raw material for the conformation of a new polymer matrix composite with increased properties favoring its industrial applications, is proposed with a zero residues approach. Low density polyethylene pellets and nonmetallic fraction particles were mixed, and due to the generation of static electricity during the mixing process, the nonmetallic particles became attached to the polyethylene pellets; the blended material was fed into a screw extruder, producing filaments of the new composite. Mechanical properties increased as the particles content increased, presenting an ultimate tensile strength going from 20 for the raw low-density polyethylene to more than 60 MPa, and a yield strength that goes from 10 to 50 MPa on the composite with 6.0 wt.% particles. Also, the flammability of the composite improved, reducing its linear burning rate and increasing the time between detachment of two consecutive drops. Nonmetallic fraction particles were oriented in the extrusion direction and had a good adhesion with the polyethylene matrix. These composites can be employed for the production of prototypes using additive manufacture. Full article

Polyethylene terephthalate glycol (PETG) and silicon nitride (Si₃N₄) were combined to create five composite materials with Si₃N₄ loadings ranging from 2.0 wt.% to 10.0 wt.%. The goal was to improve the mechanical properties of PETG in material extrusion (MEX) additive manufacturing (AM) and assess the effectiveness of Si₃N₄ as a reinforcing agent for this particular polymer. The process began with the production of filaments, which were subsequently fed into a 3D printer to create various specimens. The specimens were manufactured according to international standards to ensure their suitability for various tests. The thermal, rheological, mechanical, electrical, and morphological properties of the prepared samples were evaluated. The mechanical performance investigations performed included tensile, flexural, Charpy impact, and microhardness tests. Scanning electron microscopy and energy-dispersive X-ray spectroscopy mapping were performed to investigate the structures and morphologies of the samples, respectively. Among all the composites tested, the PETG/6.0 wt.% Si₃N₄ showed the greatest improvement in mechanical properties (with a 24.5% increase in tensile strength compared to unfilled PETG polymer), indicating its potential for use in MEX 3D printing when enhanced mechanical performance is required from the PETG polymer. Full article

Additive manufacturing (or 3D printing) of continuous carbon fiber-reinforced plastics with fused deposition modeling is a burgeoning manufacturing method because of its potential as a powerful approach to produce lightweight, high strength and complex parts without the need for a mold. Nevertheless, it cannot manufacture parts rapidly due to low throughput. This paper proposes a high-throughput additive manufacturing of continuous carbon fiber-reinforced plastics by multifilament with reference to fiber tape placement. Three filaments were fed and compaction printed simultaneously by a robotic manufacturing system. The coupled thermal-mechanical model of the filament deformation during printing was developed to eliminate the initial interval between the filaments and improved mechanical properties. Furthermore, the mathematical relationship between filament deformation and printing parameters consisting of printing temperature, printing speed and roller pressure was proposed using response surface methodology with the line width as the response. The tensile tests demonstrate that the tensile properties of printed parts are positively correlated with the line width, but not infinitely improved. The maximum tensile strength and tensile modulus are 503.4 MPa and 83.11 Gpa, respectively, which are better than those obtained by traditional methods. Void fraction and scanning electron microscope images also reveal that the appropriate line width achieved by the reasonable printing parameters contributes to the high-throughput multifilament additive manufacturing of continuous carbon fiber-reinforced plastics. The comparison results indicate that the high-throughput multifilament additive manufacturing proposed in this paper can effectively improve the speed of continuous carbon fiber-reinforced plastics additive manufacturing without degrading the mechanical performance. Full article

Copper, due to its high thermal and electrical conductivity, is used extensively in many industries such as electronics, aerospace, etc. In the literature, researchers have utilized different additive manufacturing (AM) techniques to fabricate parts with pure copper; however, each technique comes with unique pros and cons. Among others, material extrusion (MEX) is a noteworthy AM technique that offers huge potential to modify the system to be able to print copper parts without a size restriction. For that purpose, copper is mixed with a binder system, which is heated in a melt chamber and then extruded out of a nozzle to deposit the material on a bed. The printed part, known as the green part, then goes through the de-binding and sintering processes to remove all the binding materials and densify the metal parts, respectively. The properties of the final sintered part depend on the processing and post-processing parameters. In this work, nine published articles are identified that focus on the 3D printing of pure copper parts using the MEX AM technique. Depending on the type of feedstock and the feeding mechanism, the MEX AM techniques for pure copper can be broadly categorized into three types: pellet-fed screw-based printing, filament-fed printing, and direct-ink write-based printing. The basic principles of these printing methods, corresponding process parameters, and the required materials and feedstock are discussed in this paper. Later, the physical, electrical, and mechanical properties of the final parts printed from these methods are discussed. Finally, some prospects and challenges related to the shrinkage of the printed copper part during post-processing are also outlined. Full article

This paper explores the use of Discontinuous Aligned Fibre Filament (DcAFF), a novel discontinuous fibre reinforced thermoplastic filament for 3D printing, to produce structural complex parts. Compared to conventional composite manufacturing, 3D printing has great potential in steering fibres around small structural features. In this current study, the initial thin carbon fibre (CF)-poly(L-lactic acid) (PLA) tape, produced with the High Performance Discontinuous Fibre (HiPerDiF) technology, is now reshaped into a circular cross-section filament, the DcAFF, using a bespoke machine designed to be scalable to high production rates rather than using a labour-intensive manual moulding method as in previous work. The filaments are then fed to a general-purpose 3D printer. Tensile and open-hole tensile tests were considered in this paper for mechanical and processability of DcAFF. The 3D printed specimens fabricated with the DcAFF show superior tensile properties compared to other PLA-based 3D printed composites, even those containing continuous fibres. Curvilinear open-hole tensile test samples were fabricated to explore the processability and performances of such material in complex shapes. The mechanical performance of the produced specimens was benchmarked against conventionally laid-up specimens with a cut hole. Although the steered specimens produced have lower strength than the fully consolidated samples, the raster generated by the printing path has turned the failure mechanism of the composite from brittle to ductile. Full article

The utilized 3D printhead employs an innovative hot-melt extrusion (HME) design approach being fed by drug-loaded polymer granules and making filament strands obsolete. Oscillatory rheology is a key tool for understanding the behavior of a polymer melt in extrusion processes. In this study, small amplitude shear oscillatory (SAOS) rheology was applied to investigate formulations of model antihypertensive drug Metoprolol Succinate (MSN) in two carrier polymers for pharmaceutical three-dimensional printing (3DP). For a standardized printing process, the feeding polymers viscosity results were correlated to their printability and a better understanding of the 3DP extrudability of a pharmaceutical formulation was developed. It was found that the printing temperature is of fundamental importance, although it is limited by process parameters and the decomposition of the active pharmaceutical ingredients (API). Material characterization including differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA) of the formulations were performed to evaluate component miscibility and ensure thermal durability. To assure the development of a printing process eligible for approval, all print runs were investigated for uniformity of mass and uniformity of dosage in accordance with the European Pharmacopoeia (Ph. Eur.). Full article

In the current process for additive manufacturing of continuous carbon fiber reinforced resin matrix composites, the fiber and resin matrix are fed into the molten chamber, and then impregnated and compounded in the original position, and finally extruded and deposited on the substrate. It is difficult to control the ratio of fiber and resin, and to achieve good interface fusion, which results in an unsatisfactory enhancement effect. Therefore, an additive manufacturing process based on continuous carbon fiber reinforced polylactic acid composite prepreg filament was explored in this study. The effects of various process parameters on the formability of composites were studied through systematic process experiments. The results showed that the process parameters of additive manufacturing have a systematic influence on the forming quality, accuracy and efficiency, and on the mechanical properties of CFRP. Through the experimental optimization of various process parameters, a continuous and stable forming process was achieved when the nozzle aperture was 0.8 mm, the nozzle printing temperature was 240 °C, the substrate temperature was 60 °C, the wire feeding speed was 5 mm/s, the nozzle moving speed was 5 mm/s, the path bonding rate was 40%, and the printing layer thickness was 0.7 mm. Based on the optimized process parameters, direct additive manufacturing of a lightweight and high-strength composite cellular load-bearing structure could be realized. Its volume fraction of carbon fiber was approximately 7.7%, and the tensile strength was up to 224.3 MPa. Full article

Three-dimensional printing has become an unchallenged method for the manufacturing of complex shape objects. Although multicolor devices in Fuse Filament Feeder category recently have shown promising developments, their number still remains limited. The present study introduces the design of a new prototype of three-dimensional printer using Fused Filament Feeder and capable of printing multicolor objects. A single-color three-dimensional printer is used as a platform and is augmented for multicolor printing by the implementation of a mechatronic device that provides two functions. First, a transmission mechanism based on planetary gears allows feeding the selected filament color toward the printing head. The second function is provided by a combination of a central cam disk and several pushing rods. It allows selecting the filament color to be fed by the transmission system. The mechatronic device has been dimensioned to manage five different filament colors and the printing head has been modified to accommodate a five-to-one diamond nozzle. The filament shifting device is integrated into the single-color three-dimensional printer and a series of validation experiments has been carried out. These tests have demonstrated the new prototype ability to print out multicolor objects and to rival with commercial three-dimensional printers in terms of dimensional accuracy. This shows the ability of the proposed design and method to be used to upgrade a standard single-color 3D printer into a multicolor one. The presented multicolor 3D printer will be available to the 3D printing community for free. Full article

The aim of this research was the production of low-dosed filaments via hot-melt extrusion (HME) with the model drug pramipexole for the treatment of Parkinson’s disease. The active pharmaceutical ingredient (API) and one of the polymers polyvinyl alcohol (PVA) or basic butylated methacrylate copolymer (bPMMA) were fed by various dosing techniques with the aim of achieving the smallest deviation (RSD) from the target concentration of 0.1% (w/w) pramipexole. It was found that deviation from target pramipexole concentration occurred due to degradation products in bPMMA formulations. Additionally, material temperature above 120 °C led to the formation of the anhydrous form of pramipexole within the extruded filaments and need to be considered in the calculation of the recovered API. This study clearly shows that even if equilibrium state of the extrusion parameters was reached, equilibrium condition for drug content was reached relatively late in the process. In addition, the RSD calculated by the Stange–Poole equation was proposed by us to predict the final content uniformity considering the sample size of the analyzed filament. The calculated RSD, depending on sample size and drug load, can serve as upper and lower limits of variation from target concentration and can be used to evaluate the deviations of drug content in equilibrium conditions of the HME process. The lowest deviations from target concentration in equilibrium condition for drug content were obtained in filaments extruded from previously prepared granule mixtures (RSD = 6.00%, acceptance value = 12.2). These promising results can be transferred to other API–excipient combinations to produce low-dosed filaments, which can be used for, e.g., fused filament 3D printing. The introduced calculation of the RSD by Stange–Poole equation can be used for precise determination of the homogeneity of an extruded batch. Full article

In contrast to the traditional 3D printing process, where material is deposited layer-by-layer on horizontal flat surfaces, conformal 3D printing enables users to create structures on non-planar surfaces for different and innovative applications. Translating a 2D pattern to any arbitrary non-planar surface, such as a tessellated one, is challenging because the available software for printing is limited to planar slicing. The present research outlines an easy-to-use mathematical algorithm to project a printing trajectory as a sequence of points through a vector-defined direction on any triangle-tessellated non-planar surface. The algorithm processes the ordered points of the 2D version of the printing trajectory, the tessellated STL files of the target surface, and the projection direction. It then generates the new trajectory lying on the target surface with the G-code instructions for the printer. As a proof of concept, several examples are presented, including a Hilbert curve and lattices printed on curved surfaces, using a conventional fused filament fabrication machine. The algorithm’s effectiveness is further demonstrated by translating a printing trajectory to an analytical surface. The surface is tessellated and fed to the algorithm as an input to compare the results, demonstrating that the error depends on the resolution of the tessellated surface rather than on the algorithm itself. Full article

Polypropylene (PP) is an engineered thermoplastic polymer widely used in various applications. This work aims to enhance the properties of PP with the introduction of titanium dioxide (TiO₂) nanoparticles (NPs) as nanofillers. Novel nanocomposite filaments were produced at 0.5, 1, 2, and 4 wt.% filler concentrations, following a melt mixing extrusion process. These filaments were then fed to a commercially available fused filament fabrication (FFF) 3D printer for the preparation of specimens, to be assessed for their mechanical, viscoelastic, physicochemical, and fractographic properties, according to international standards. Tensile, flexural, impact, and microhardness tests, as well as dynamic mechanical analysis (DMA), Raman, scanning electron microscopy (SEM), melt flow volume index (MVR), and atomic force microscopy (AFM), were conducted, to fully characterize the filler concentration effect on the 3D printed nanocomposite material properties. The results revealed an improvement in the nanocomposites properties, with the increase of the filler amount, while the microstructural effect and processability of the material was not significantly affected, which is important for the possible industrialization of the reported protocol. This work showed that PP/TiO₂ can be a novel nanocomposite system in AM applications that the polymer industry can benefit from. Full article