Fused Deposition Modeling Printing Research Articles

Generation of Efficient Iso-Planar Printing Path for Multi-Axis FDM Printing

The emerging multi-axis fused deposition modeling (FDM) printing process is a powerful technology for fabricating complicated 3D models that otherwise would require extensive support structures or suffer the severe stair-case effect if printed on a conventional three-axis FDM printer. However, because of the addition of two rotary axes which enables the printing nozzle to change its orientation continuously, and the fact that the printing layer is now curved, determining how a nozzle printing path to cover the layer becomes a non-trivial issue, since the rotary axes of the printer in general have a much worse kinematic capacity than the linear axes. In this paper, specifically targeting robotic printing, we first propose an efficiency indicator called the material deposition rate which considers both the local geometry of the layer surface and the kinematic capacities of the printer. By maximizing this indicator globally, a best drive plane direction is found, and then the classic iso-planar method is adopted to generate the printing path for the layer, which not only upholds the specified printing quality but also strives to maximize the kinematic capacities of the printer to minimize the total printing time. Preliminary experiments in both computer simulation and physical printing are carried out and the results give a positive confirmation on the proposed method.

Additive manufacturing of polyamide nanocomposites for electrostatic charge dissipation applications

Polyamide 6 (PA 6) nanocomposites are viable engineered nanocomposite materials with potential application in electrostatic discharge dissipation applications. Creating an electrically conductive path to dissipate electrostatic charges in such materials can be a viable solution to electrostatic discharge (ESD) concerns. The addition of nanofillers can also enhance mechanical properties of the parent polyamide 6, a structural thermoplastic ideal for 3D printing via fused deposition modelling (FDM). While improving the ESD capability, it is imperative to sustain the structural integrity of the nanocomposites. Hence, this study evaluated the mechanical, thermal, and electrical properties of 3D printed PA6 nanocomposites for electrostatic discharge applications. 3 and 5 wt% of carbon nanofibers (CNF) was compounded with PA6 using co-rotating twin screw extruder to produce 1.75 mm diameter monofilaments for fused deposition modelling (FDM). The test samples were printed using commercial-off-the-shelf (COTS) 3D printer, Lulzbot TAZ 6 FDM printer. Mechanical, electrical, and thermal characterization was carried out according to their respective ASTM standard. The tensile and flexural properties were enhanced by 3 wt% addition of CNF, but no significant improvement was observed at 5 wt%. The CNF nanocomposites exhibited good thermal stability and crystallization phenomenon at both loading levels. The volume resistivity of the of the PA6 matrix was reduced to order of 1011 and 1012 by 3 wt% and 5 wt% CNF addition respectively, which seems promising for manufacturing static discharge products.

Structural Investigation of Delicate-Geometry Fused Deposition Modeling Additive Manufacturing Scaffolds: Experiment and Analytics

Additive manufacturing is a rapidly expanding technology in many scientific fields like tissue engineering. One of the most essential duties of tissue engineering scaffolds is to provide sufficient mechanical strength for the injured bone tissue. Scaffold architecture plays a significant role in its mechanical properties. Here, six delicate different geometry computer-aided design models with identical porosity were designed. The sets of 0/90, 0/45/135/90, 0/60/120, and their shifted models as the most prevalent scaffold geometries were fabricated by fused deposition modeling printer through the optimized processing parameters and were investigated by the upset test. Their modified models according to printing procedure changes were redesigned, and finite element analysis (FEA) simulations were accomplished through a simplifying strategy. Mechanical performances of the designed scaffolds were evaluated, and a good agreement was observed between the FEA and experiments. The strongest patterns were derived via evaluation of three aspects of scaffold elastic modulus, scaffold yield strength, and a newly defined parameter named “scaffold geometry rupture resistance factor”. The large difference between Young's modulus of 0/90 (230.44 MPa) and 0/90 shifted (156.56 MPa) indicated the role of scaffold geometry in mechanical properties. The mechanical effect of layer pattern sequence change was also investigated.

Mechanical properties comparison between new and recycled polyethylene terephthalate glycol obtained from fused deposition modelling waste

The recycling of materials and the efficient use of resources are nowadays fundamental in a circular economy perspective. This concept also applies to additive manufacturing (AM) where waste can be reused to produce new material. Using mostly thermoplastic polymers, fused deposition modeling (FDM) is an AM technique that allows to melt waste materials and, successively, using a suitable extruder, obtain new filament. In the process, polymers are subject to multiple re-melting and polymer orientations by extrusion operations. The aim of this work is to evaluate the influence of the recycling process over polyethylene terephthalate glycol-modified (PETG) mechanical properties by tensile testing of samples produced using pure and recycled material. Furthermore, filament itself has been tested to evaluate recycle process influence before FDM printing.

A Sensorized Soft Pneumatic Actuator Fabricated with Extrusion-Based Additive Manufacturing

Soft pneumatic actuators with a channel network (pneu-net) based on thermoplastic elastomers are compatible with fused deposition modeling (FDM). However, conventional filament-based fused deposition modeling (FDM) printers are not well suited for thermoplastic elastomers with a shore hardness (Sh < 70A). Therefore, in this study, a pellet-based FDM printer was used to print pneumatic actuators with a shore hardness of Sh18A. Additionally, the method allowed the in situ integration of soft piezoresistive sensing elements during the fabrication. The integrated piezoresistive elements were based on conductive composites made of three different styrene-ethylene-butylene-styrene (SEBS) thermoplastic elastomers, each with a carbon black (CB) filler with a ratio of 1:1. The best sensor behavior was achieved by the SEBS material with a shore hardness of Sh50A. The dynamic and quasi-static sensor behavior were investigated on SEBS strips with integrated piezoresistive sensor composite material, and the results were compared with TPU strips from a previous study. Finally, the piezoresistive composite was used for the FDM printing of soft pneumatic actuators with a shore hardness of 18 A. It is worth mentioning that 3 h were needed for the fabrication of the soft pneumatic actuator with an integrated strain sensing element. In comparison to classical mold casting method, this is faster, since curing post-processing is not required and will help the industrialization of pneumatic actuator-based soft robotics.

Research progress in manufacturing multifunctional polymer composite materials based on fused deposition modeling technology

3D printing technology, also known as additive manufacturing technology, is based on materials, mechanical control, computer-assisted design and other multi-cross disciplines. 3D printing enables fabrication of complex structure materials which cannot be fabricated by traditional methods. Fused deposition modeling (FDM) is one of the most well-known 3D printing technologies due to its merits like cost-effectiveness, simple in equipment and ease of operation, which has been widely used in aerospace, medical and auto industry. This review introduced the overall layout, development and planning of 3D printing technologies. This review also systematically summarized the characteristics and classifications of common 3D printing technologies, and mainly focused on the principles, advantages and requirements for the FDM technology. Especially, we aim to outline the basic requirements of polymer that suitable for FDM printing and introduce the applications of carbon-based polymer composite materials in the FDM manufacturing process. In addition, recent advances of FDM printing in fabrication of functional polymer composite materials and parts, including biomedical, electrical and thermal conductive polymer composites are reviewed in detail. The prospects for the research and applications of FDM towards manufacturing of high-performance and multifunctional polymer composite materials are proposed. At last, the challenges and key problems that need to be solved in FDM processing are considered and prospected.

A review on the fused deposition modeling (FDM) 3D printing: Filament processing, materials, and printing parameters

Abstract This study aims to review research the progress on factors that affect the 3D printing results of the fused deposition modeling (FDM) process. The review is carried out by mapping critical parameters and characteristics determining FDM parameters, the effects of each parameter, and their interaction with other parameters. The study started from the filament manufacturing process, filament material types, and printing parameters of FDM techniques. The difference in each section has determined different parameters, and the respective relationships between parameters and other determinants during printing have a significant effect on printing results. This study also identifies several vital areas of previous and future research to optimize and characterize the critical parameters of the FDM printing process and FDM filament manufacturing.

Design of ultrasonic standing wave levitation support for three-dimensional printed filaments.

Fused deposition modeling (FDM) three-dimensional (3D) printing is the process of forming a part by depositing molten thermoplastic materials layer by layer. Support structures need to be added below the overhangs or bridges in 3D printing. This paper proposes an idea for support-free FDM printing by studying the method of filament levitation. In this paper, an ultrasonic phased array device is designed, and different slender objects with length much longer than the sound wavelength are levitated in the air by multiple standing wave points. Experiments show that slender objects can be stably held at the sound pressure nodes in the standing wave field. After adding the ultrasonic field in FDM printing, the maximum deformation of single filament due to gravity on the bridge structure decreases from 5 to 2 mm. This proves that it is feasible for an ultrasonic phased array system to play an important role in the field of support-free FDM printing.

Short review of nonplanar fused deposition modeling printing

Short review of nonplanar fused deposition modeling printing

Ionic Liquid-Assisted 3D Printing of Self-Polarized β-PVDF for Flexible Piezoelectric Energy Harvesting.

Three-dimensional (3D) printing technologies have unparalleled advantages in constructing piezoelectric devices with three-dimensional structures, which are conducive to improving the efficiency of energy harvesting. Among them, fused deposition modeling (FDM) is the most widely used thanks to its low cost and wide range of molding materials. However, as the best piezoelectric polymer, a high electroactive β-phase poly(vinylidene fluoride) (PVDF) piezoelectric device cannot be directly obtained by FDM printing because the β-crystal is unstable at the molten state. Herein, we develop for the first time ionic liquid (IL)-assisted FDM for direct printing of β-PVDF piezoelectric devices. An IL can induce and maintain β crystals during melt extrusion and FDM printing, ensuring that the β-crystal in the printed PVDF device is as high as 98.3%, which is the highest in 3D-printed PVDF as far as we know. Furthermore, the shearing force provided by the FDM facilitates the directional arrangement of the dipoles, resulting in the printed PVDF device having self-polarization characteristics without poling. Finally, the piezoelectric output voltage of the 3D-printed PVDF device is 4.7 times that of the flat PVDF device, and its area current density (17.5 nA cm-2) is more than that of the reported 3D-printed PVDF piezoelectric device in the literature by two orders of magnitude. The one-step 3D printing strategy proposed in this paper can realize the rapid preparation of complex-shaped and lightweight self-polarized β-PVDF-based piezoelectric devices for energy harvesting.

3D-PAD: Paper-Based Analytical Devices with Integrated Three-Dimensional Features.

This paper describes the use of fused deposition modeling (FDM) printing to fabricate paper-based analytical devices (PAD) with three-dimensional (3D) features, which is termed as 3D-PAD. Material depositions followed by heat reflow is a standard approach for the fabrication of PAD. Such devices are primarily two-dimensional (2D) and can hold only a limited amount of liquid samples in the device. This constraint can pose problems when the sample consists of organic solvents that have low interfacial energies with the hydrophobic barriers. To overcome this limitation, we developed a method to fabricate PAD integrated with 3D features (vertical walls as an example) by FDM 3D printing. 3D-PADs were fabricated using two types of thermoplastics. One thermoplastic had a low melting point that formed hydrophobic barriers upon penetration, and another thermoplastic had a high melting point that maintained 3D features on the filter paper without reflowing. We used polycaprolactone (PCL) for the former, and polylactic acid (PLA) for the latter. Both PCL and PLA were printed with FDM without gaps at the interface, and the resulting paper-based devices possessed hydrophobic barriers consisting of PCL seamlessly integrated with vertical features consisting of PLA. We validated the capability of 3D-PAD to hold 30 μL of solvents (ethanol, isopropyl alcohol, and acetone), all of which would not be retained on conventional PADs fabricated with solid wax printers. To highlight the importance of containing an increased amount of liquid samples, a colorimetric assay for the formation of dimethylglyoxime (DMG)-Ni (II) was demonstrated using two volumes (10 μL and 30 μL) of solvent-based dimethylglyoxime (DMG). FDM printing of 3D-PAD enabled the facile construction of 3D structures integrated with PAD, which would find applications in paper-based chemical and biological assays requiring organic solvents.

Development and Accuracy Test of a Fused Deposition Modeling (FDM) 3D Printing using H-Bot Mechanism

Additive manufacturing process known as the 3D printing process is an advanced manufacturing process including one of the components to support industrial revolution 4.0. The initial development of a 3D printing machine at Sampoerna University is the background of this research. The 3D printing setup of Fused Deposition Modeling (FDM) was built using H-bot moving mechanism by considering the rigidity aspect. The FDM printing method is selected due to its cost and reliability. In this early development, the brackets were custom made using a 3D printer with Polylactic Acid (PLA) material. The result showed that the software worked properly in accordance with the assembled mechanical and electrical parts. The 3D printer could print simple objects such as planes and cubes with small dimensions. However, the printing specimen still lacked accuracy caused by the less rigidity of linear rail brackets, less coplanar belt arrangement, and error in some electronic components.

Mechanical performance of honeycomb sandwich structures built by FDM printing technique

Honey Comb Sandwich Structures (HCSS) have numerous applications in aerospace, automobile, and satellite industry because of their properties like high strength to weight ratio, stiffness and impact strength. Fused Deposition Modeling (FDM) is a process which, through its flexibility, simple processing, short manufacturing time, competitive prices and freedom of design, has an ability to enhance the functionality of HCSS. This paper investigates the mechanical behavior (i.e. flexural, edgewise compression and Interfacial bond strength) of FDM-built HCSS. The influence of face/core material was examined by manufacturing four types of specimens namely ABS core with Composite (PLA + 15% carbon fibers) face sheets, ABS core with PLA face sheets, TPU core with composite face sheets and TPU core with PLA face sheets. To measure the effect of face sheets geometry, raster layup was varied at 0°/90° and 45°/−45°. The mechanical characterization revealed that an optimum combination of materials is ABS core with composite face sheets having raster layup of 0°/90°. This study indicates that HCSS with complex lamination schemes and adequate mechanical properties could be manufactured using FDM which may widen the applications of FDM on an industrial scale.

Recent Progress of Fused Deposition Modeling (FDM) 3D Printing: Constructions, Parameters and Processings

Fused Deposition Modeling (FDM) is the most widely used 3D printing technique. The use and development of FDM cover various fields such as automotive, airplane, to biomedical. Many studies have been conducted to study the effect of various printing parameters and post-processing treatment on the performance of printing results with FDM. This literature study aims to compile and summarize the latest studies related to the effect of FDM process parameters and post-processing treatment as well as prospects and challenges. The review found that the combination of several synchronized parameter processes can produce parts that are printed better because several parameters are interrelated and can complement to each other. In addition, the quality of FDM printing results is generally found to be better with post-processing treatment although it requires more effort that might not always be feasible for some applications.

Identifying Elastic Constants for PPS Technical Material When Designing and Printing Parts Using FDM Technology.

This paper introduces a methodology to study the anisotropic elastic constants of technical phenylene polysulfide thermoplastic (PPS), printed using fused deposition modeling (FDM) in order to provide designers with a guide to achieve the required mechanical properties in a printed part. The properties given by the manufacturer are usually taken from injected samples and these are not the real properties for printed parts. Compared to other plastic materials, PPS offers higher mechanical and thermal resistance, lower moisture absorption, higher dimensional stability, is highly resistant to chemical attacks and environmental aging, and its fireproof performance is good. One of the main difficulties presented when calculating and designing for FDM printing is that printed parts present anisotropic behavior i.e., they do not have the same properties in different directions. Haltera-type samples were printed in the three manufacturing directions according to optimum parameters for material printing, aimed at calculating the anisotropic matrix of the material. The samples were tested in order to meet standards and values for elastic modulus, shear modulus and tensile strength were obtained, using Digital Image Correlation System to measure the deformations. An approximated transversally isotropic matrix was defined using the obtained values. The fracture was analyzed using SEM microscopy to check whether the piece was printed correctly. Finally, the obtained matrix was validated by a flexural test and a finite element simulation.

Tailoring immediate release FDM 3D printed tablets using a quality by design (QbD) approach

The aims of this work were to produce immediate release printed tablets using fused deposition modelling (FDM) technique and to systematically explore the effects of different compositions on drug release by Quality by Design approach. Screening studies of various drug loadings and excipients were conducted by hot melt extrusion and FDM printing to set up the appropriate limit of each independent factor (critical material attribute, CMA) in Design of Experiment. This study demonstrated that the use of polymeric mixture containing different theophylline loadings (10, 30 and 60% w/w) in combination with multiple pharmaceutical polymers (hydroxy propyl cellulose (HPC), Eudragit® EPO, Kollidon® VA 64) and disintegrant (sodium starch glycolate) were successfully hot melt-extruded and FDM printed with no plasticizer. Rheological measurement was performed to understand the critical process parameters (CPP) while the mechanical property of extrudable and printable filaments was investigated by 3-point test for the formulation development. Surprisingly, HPC were found to be superior as a flexibility modifier in all printable filaments. A range of pharmaceutical characterizations were examined to ensure the critical quality attributes (CQA). Characteristic dissolution profiles were obtained. D-optimal mixture design of 17 formulations suggested that theophylline release was considerably affected by the combined action of different excipients and could predict the optimum formulation with the required quality target product profile (QTPP) in pharmacopoeia (85% release at 30 min). Therefore, this can be a useful platform to develop immediate release products for a specific group of patients commercially.

Strategies and mechanisms to improve the printability of pharmaceutical polymers Eudragit® EPO and Soluplus®

The poor printability of most pharmaceutical polymers greatly restricts the application of the fused deposition modeling (FDM) technique in the field of personalized pharmaceutical preparations. General strategies to improve printability and provide practical guidelines for the optimization of formulations are lacking. Moreover, the mechanism associated with the smooth printing process of modified printing materials needs to be investigated. In this study, three different strategies were used to improve the FDM printability of typical brittle polymers with poor printability. The relationship among additives, material properties, and printability was explored. The finite element method was used to simulate the radial stress–strain behavior of the filament, while computational fluid dynamics was used to simulate the axial melt flow field in the printing head. It was found that the addition of an inert filler (i.e., talc), a drug with high melting points (i.e., diclofenac sodium), and a polymer with high strength (i.e., plasticized ethylcellulose) effectively improved the printability of plasticized Eudragit® EPO and Soluplus®. In addition, regulating the mechanical properties of filaments improved printability, and it was deduced that printable filaments should have neither very low stiffness nor very low flexibility. The suitable melt viscosity or shear-thinning property of the printing material facilitated smooth extrusion without filament breakage or nozzle blockage. The results of this study also showed that simulation could assist in understanding the stress–strain behavior of filaments and the flow field of melts during FDM printing.

Quality Control in 3D Printing: Accuracy Analysis of 3D-Printed Models of Patient-Specific Anatomy.

As comparative data on the precision of 3D-printed anatomical models are sparse, the aim of this study was to evaluate the accuracy of 3D-printed models of vascular anatomy generated by two commonly used printing technologies. Thirty-five 3D models of large (aortic, wall thickness of 2 mm, n = 30) and small (coronary, wall thickness of 1.25 mm, n = 5) vessels printed with fused deposition modeling (FDM) (rigid, n = 20) and PolyJet (flexible, n = 15) technology were subjected to high-resolution CT scans. From the resulting DICOM (Digital Imaging and Communications in Medicine) dataset, an STL file was generated and wall thickness as well as surface congruency were compared with the original STL file using dedicated 3D engineering software. The mean wall thickness for the large-scale aortic models was 2.11 µm (+5%), and 1.26 µm (+0.8%) for the coronary models, resulting in an overall mean wall thickness of +5% for all 35 3D models when compared to the original STL file. The mean surface deviation was found to be +120 µm for all models, with +100 µm for the aortic and +180 µm for the coronary 3D models, respectively. Both printing technologies were found to conform with the currently set standards of accuracy (<1 mm), demonstrating that accurate 3D models of large and small vessel anatomy can be generated by both FDM and PolyJet printing technology using rigid and flexible polymers.

Design and Characterization of a Screw Extrusion Hot-End for Fused Deposition Modeling.

The filament is the most widespread feedstock material form used for fused deposition modeling printers. Filaments must be manufactured with tight dimensional tolerances, both to be processable in the hot-end and to obtain printed objects of high quality. The ability to successfully feed the filament into the printer is also related to the mechanical properties of the filament, which are often insufficient for pharmaceutically relevant excipients. In the scope of this work, an 8 mm single screw hot-end was designed and characterized, which allows direct printing of materials from their powder form and does not require an intermediate filament. The capability of the hot-end to increase the range of applicable excipients to fused deposition modeling was demonstrated by processing and printing several excipients that are not suitable for fused deposition modeling in their filament forms, such as ethylene vinyl acetate and poly(1-vinylpyrrolidone-co-vinyl acetate). The conveying characteristic of the screw was investigated experimentally with all materials and was in agreement with an established model from literature. The complete design information, such as the screw geometry and the hot-end dimensions, is provided in this work.

Effect of Layer Directions on Internal Structures and Tensile Properties of 17-4PH Stainless Steel Parts Fabricated by Fused Deposition of Metals.

17-4PH stainless steel specimens were fabricated by fused deposition of metals (FDMet) technology, which combines 17-4PH particles with an organic binder. FDMet promises a low-cost additive manufacturing process. The present research aims to clarify the influence of layer directions in the 3D printing process on the mechanical and shrinkage properties of as-sintered and as-aged specimens. All specimens (the as-sintered and as-aged specimens printed in three layer directions) exhibited high relative density (97.5–98%). The highest ultimate strengths (880 and 1140 MPa in the as-sintered and as-aged specimens, respectively) were obtained when the layer direction was perpendicular to the tensile direction. Conversely, the specimens printed with their layer direction parallel to the tensile direction presented a low ultimate strength and low strain at breakage. The fact that the specimens with their layer direction parallel to the tensile direction presented a low ultimate strength and low strain at breakage is a usual behavior of parts obtained by means of FDM. The SEM images revealed oriented binder domains in the printed parts and oriented voids in the sintered parts. It was assumed that large binder domains in the filament were oriented perpendicular to the layer directions during the fused deposition modeling printing, and remained as oriented voids after sintering. Stress concentration in the oriented void defects was likely responsible for the poor tensile properties of these specimens.