Conventional Fused Deposition Modeling Research Articles

A novel pellet-based 3D printing of high stretchable elastomer

Elastomers, known for their high stretchability and flexibility, are widely used in high-tech applications. However, traditional manufacturing methods for elastomeric part production have limitations. 3D printing, particularly fused deposition modeling (FDM), offers a promising alternative by allowing the fabrication of customized elastomers with desired shapes and properties. Conventional filament-based FDM techniques struggle to print elastomers. This article presents a novel approach for 3D printing polyolefin elastomer (POE) using a direct pellet printing technique. A customized pellet printer with a pneumatic pressure feeding system was used that eliminates filament buckling issues commonly associated with conventional filament-based 3D printing methods. The mechanical properties and microstructure of the printed parts were analyzed to evaluate the suitability of the technique for producing high-quality elastomeric components. SEM images indicated a high-quality and accurate printing method; however, there are micro-holes between the raster due to the high shrinkage rate of POE and increasing the nozzle temperature improves the print quality. The mechanical properties of the printed samples exhibited remarkable formability, with elongation reaching up to 1965%. It is also found that as the nozzle temperature increased, the strength, elongation, and bonding between layers improved significantly. This innovative 3D printing technique has the potential for various applications such as soft robotics and wearable electronics.

Ultra-Broad Linear Range and Sensitive Flexible Piezoresistive Sensor Using Reversed Lattice Structure for Wearable Electronics.

Flexible pressure sensors have attracted significant attention owing to their broad applicability in wearable electronics and human-machine interfaces. However, it is still challenging to simultaneously achieve a broad sensing range and high linearity. Here, we present a reversed lattice structure (RLS) piezoresistive sensor obtained through a layer-level engineered additive infill structure via conventional fused deposition modeling three-dimensional (3D) printing. The optimized RLS piezoresistive sensor attained a pressure sensing range (0.03-1630 kPa) with high linearity (coefficient of determination, R2 = 0.998) and sensitivity (1.26 kPa-1) due to the structurally enhanced compressibility and spontaneous transition of dominant sensing mechanism of the sensor. It also exhibited great mechanical/electrical durability and a rapid response/recovery time (170/70 ms). This remarkable performance enables the detection of various human motions over a broad spectrum, from pulse detection to human walking. Finally, a wearable electronic glove was developed to analyze the pressure distribution in various situations, thereby demonstrating its applicability in multipurpose wearable electronics.

Veering to a Continuous Platform of Fused Deposition Modeling Based 3D Printing for Pharmaceutical Dosage Forms: Understanding the Effect of Layer Orientation on Formulation Performance.

Three-dimensional (3D) printing of pharmaceuticals has been centered around the idea of personalized patient-based 'on-demand' medication. Fused deposition modeling (FDM)-based 3D printing processes provide the capability to create complex geometrical dosage forms. However, the current FDM-based processes are associated with printing lag time and manual interventions. The current study tried to resolve this issue by utilizing the dynamic z-axis to continuously print drug-loaded printlets. Fenofibrate (FNB) was formulated with hydroxypropyl methylcellulose (HPMC AS LG) into an amorphous solid dispersion using the hot-melt extrusion (HME) process. Thermal and solid-state analyses were used to confirm the amorphous state of the drug in both polymeric filaments and printlets. Printlets with a 25, 50, and 75% infill density were printed using the two printing systems, i.e., continuous, and conventional batch FDM printing methods. Differences between the two methods were observed in the breaking force required to break the printlets, and these differences reduced as the infill density went up. The effect on in vitro release was significant at lower infill densities but reduced at higher infill densities. The results obtained from this study can be used to understand the formulation and process control strategies when switching from conventional FDM to the continuous printing of 3D-printed dosage forms.

Optimization of 3D Printed Rapid Prototype Deep Drawing Tools for Automotive and Railway Sheet Material Testing

The main objective of this research is to identify optimal printing strategies and PLA (polylactic acid) filament materials to produce rapid prototype deep drawing tools. Additive 3D printing technologies have been applied for a long time to produce tools, but the research is unique in that it uses conventional and various reinforced PLA materials with conventional FDM (Fused Deposition Modeling) printers. The advantage of this method is that PLA is easy to print and recycle and does not require expensive or special printers, this also gives the article its novelty. A further aim was to produce the tools using commercially available low-end printers. DX53D 0.8 mm thick body steel and AlMg3 2.5 mm thick sheet were the materials to be molded for the tests. The test tool was an Erichsen deep drawing punch. Tool wear was tested using the GOM ATOS measuring system, an optical coordinate measuring machine based on the DIC (Digital Image Correlation) principle, which is also popular in the automotive industry. The study aims to determine the 3D printing and material parameters that can safely produce a minimum batch of 100 parts.

Electric field assisted fused deposition modeling for improving nozzle cleanliness

Fused deposition modeling (FDM) is one of the most popular additive manufacturing processes. It has been utilized in a variety of research fields and applications. However, little attention has been paid to the nozzle cleanliness issue in the FDM process. Debris of extruded polymer materials can easily build up on the nozzle surface in the printing process and the accumulated debris typically falls on the actual printing area, which degrades the quality of printed parts. This paper innovated an approach to reduce polymer debris build-up on the nozzle during the FDM printing process. An electric-field-assisted FDM (E-FDM) process was proposed to improve the nozzle cleanliness. E-FDM utilizes a high voltage power supply to generate an electrostatic force between the nozzle and build plate, which has great potential to avoid accumulations of melted thermoplastic materials on FDM nozzles. To verify the effectiveness of the E-FDM process, both E-FDM and conventional FDM processes were used to print test specimens for certain durations of time. Debris built up on the nozzle surface was characterized by 3D scanning to quantify the volume changes of the nozzle. The E-FDM printing reduced debris accumulation by 47% after ∼5 hours of printing and over 80% after ∼15 hours of printing as compared to the conventional FDM process. The results demonstrated the effectiveness of the electric-field-assisted FDM process in reducing the nozzle debris built up on the nozzle surface.

Pellet-based fused deposition modeling for the development of soft compliant robotic grippers with integrated sensing elements

Fused deposition modeling (FDM) has some advantages compared to other additive manufacturing techniques, such as the in situ integration of functional components, like sensors, and recyclability of parts. However, conventional filament-based FDM techniques are limited to thermoplastic elastomers with a Shore hardness above 70 A, thus it has marginal compatibility with soft robotic structures. Due to recently emerging pellet-based FDM printer technology, the fabrication of soft grippers with low Shore hardness has become possible. In this study, styrene based thermoplastic elastomers (TPS) were used to print elastic strips and soft gripper structures down to a Shore hardness of 25 A with an integrated strain sensing element (piezoresistive sensor). Printing on a soft rather than rigid substrate affects the integration of the printed thread on the substrate, because of the softness and relaxation, during the printing softness. It was seen that integrating the sensing element on a substrate with higher Shore hardness decreased the elongation at the point of fracture and the sensitivity of the sensing element. A soft compliant gripper structure with an integrated sensing layer was printed with the TPS-based elastomers successfully, and even due to the complex deformation of the compliant gripper structure, several positions could be detected successfully. Opened and closed position of the gripper, as well as, size recognition of spools of different sizes could be monitored by the piezoresistive printed sensor layer. The most sensitive sensing performance was obtained with the TPS of the lower Shore hardness (25 A), as the value of relative change in resistance was 1, followed by the gripper of Shore hardness 65 A and a relative change in resistance of 0.51. With this study, we demonstrated that pellet-based FDM printers can be used, to print potential soft robotic structures with in-situ integrated sensor structures.

Fabrication of a Soft Robotic Gripper With Integrated Strain Sensing Elements Using Multi-Material Additive Manufacturing.

With the purpose of making soft robotic structures with embedded sensors, additive manufacturing techniques like fused deposition modeling (FDM) are popular. Thermoplastic polyurethane (TPU) filaments, with and without conductive fillers, are now commercially available. However, conventional FDM still has some limitations because of the marginal compatibility with soft materials. Material selection criteria for the available material options for FDM have not been established. In this study, an open-source soft robotic gripper design has been used to evaluate the FDM printing of TPU structures with integrated strain sensing elements in order to provide some guidelines for the material selection when an elastomer and a soft piezoresistive sensor are combined. Such soft grippers, with integrated strain sensing elements, were successfully printed using a multi-material FDM 3D printer. Characterization of the integrated piezoresistive sensor function, using dynamic tensile testing, revealed that the sensors exhibited good linearity up to 30% strain, which was sufficient for the deformation range of the selected gripper structure. Grippers produced using four different TPU materials were used to investigate the effect of the Shore hardness of the TPU on the piezoresistive sensor properties. The results indicated that the in situ printed strain sensing elements on the soft gripper were able to detect the deformation of the structure when the tentacles of the gripper were open or closed. The sensor signal could differentiate between the picking of small or big objects and when an obstacle prevented the tentacles from opening. Interestingly, the sensors embedded in the tentacles exhibited good reproducibility and linearity, and the sensitivity of the sensor response changed with the Shore hardness of the gripper. Correlation between TPU Shore hardness, used for the gripper body and sensitivity of the integrated in situ strain sensing elements, showed that material selection affects the sensor signal significantly.

Hollow-core antiresonant terahertz fiber-based TOPAS extruded from a 3D printer using a metal 3D printed nozzle

We report the use of a terahertz (THz) transparent material, cyclic olefin copolymer (COC or TOPAS), for fabricating a hollow-core antiresonant fiber that provides an electromagnetic wave guidance in the THz regime. A novel fabrication technique to realize a hollow-core antiresonant polymer optical fiber (HC-ARPF) for THz guidance is proposed and demonstrated. The fiber is directly extruded in a single-step procedure using a conventional fused deposition modeling 3D printer. The fiber geometry is defined by a structured nozzle manufactured with a metal 3D printer, which allows tailoring of the nozzle design to the various geometries of microstructured optical fibers. The possibility to use the HC-ARPF made from TOPAS for guiding in the THz region is theoretically and experimentally assessed through the profile of mode simulation and time-frequency diagram (spectrogram) analysis.

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.

PolyChemPrint: A hardware and software framework for benchtop additive manufacturing of functional polymeric materials

AbstractAdditive manufacturing (AM, 3D Printing) of hierarchical polymer structures for a targeted function represents a grand challenge in the field of polymer science and engineering. Because advanced functional materials often do not possess suitable mechanical and rheological properties for conventional fused deposition modeling, a key challenge that researchers face is in integrating custom deposition tool heads that enable printing of non‐filamentary materials while preserving synchrony with the motion axes. In this article, we demonstrate a highly versatile hardware and software platform for melt and solution‐phase benchtop AM and highlight patterning and post‐deposition processing of a series of non‐filament forming functional polymers, including PS‐b‐PLA bottlebrush block copolymers, semiconducting polymer DPP2T‐TT, conducting polymer PEDOT:PSS [poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate)], and an SiO2‐PE nanoporous polymer matrix composite. We present a free and open‐source Python module, PolyChemPrint, which serves as a research‐optimized AM control software. The cross‐platform (Windows/Linux) software is designed to be extremely flexible in terms the hardware that can be connected and a detailed user manual and developer guide are provided for use by researchers without extensive computer programming experience. Finally, we provide extensive details of the hardware used for operation of low‐ and high‐pressure pneumatic extruders and a laser module as rapidly interchangeable tool heads.

Effects of Continuous Printing on Fused Deposition-Modeled One-Way Large-Sized Parts

One of the shortcomings of fused deposition modeling (FDM), a common and widely used additive manufacturing or 3D printing technique, is the limited size of the manufactured parts. Separately printing and gluing the parts is a common solution. In this study, a method of continuous printing for manufacturing one-way large-sized parts was proposed. Using the proposed method, FDM samples were fabricated with different interval times and linking-up locations. The mechanical properties, fracture behavior, and morphological structure were carefully investigated and compared with those obtained by conventional FDM and separately printing/gluing the parts. The results show that continuous printing helps to improve the mechanical properties of one-way large-sized FDM parts. After the interval time and linking-up location are optimized, the FDM parts have good mechanical properties, fracture behavior, and morphology. Thus, the proposed method is feasible and efficient for the continuous printing of one-way large-sized parts.

Fabrication of Drug-Eluting Nano-Hydroxylapatite Filled Polycaprolactone Nanocomposites Using Solution-Extrusion 3D Printing Technique

Polycaprolactone/nano-hydroxylapatite (PCL/nHA) nanocomposites have found use in tissue engineering and drug delivery owing to their good biocompatibility with these types of applications in addition to their mechanical characteristics. Three-dimensional (3D) printing of PCL/nHA nanocomposites persists as a defiance mostly because of the lack of commercial filaments for the conventional fused deposition modeling (FDM) method. In addition, as the composites are prepared using FDM for the purpose of delivering pharmaceuticals, thermal energy can destroy the embedded drugs and biomolecules. In this report, we investigated 3D printing of PCL/nHA using a lab-developed solution-extrusion printer, which consists of an extrusion feeder, a syringe with a dispensing nozzle, a collection table, and a command port. The effects of distinct printing variables on the mechanical properties of nanocomposites were investigated. Drug-eluting nanocomposite screws were also prepared using solution-extrusion 3D printing. The empirical outcomes suggest that the tensile properties of the 3D-printed PCL/nHA nanocomposites increased with the PCL/nHA-to-dichloromethane (DCM) ratio, fill density, and print orientation but decreased with an increase in the moving speed of the dispensing tip. Furthermore, printed drug-eluting PCL/nHA screws eluted high levels of antimicrobial vancomycin and ceftazidime over a 14-day period. Solution-extrusion 3D printing demonstrated excellent capabilities for fabricating drug-loaded implants for various medical applications.

CORA hand: a 3D printed robotic hand designed for robustness and compliance

This work presents design and experimental evaluation of CORA (COmpliant Robotic hAnd), a robotic hand designed for easy manufacturing and maintenance, and for robustness and compliance in real operational environments. It takes advantage of recent soft-polymer printable filaments to obtain intrinsic compliance during grasping and accidental contacts. All parts are designed and optimized for manufacturing with conventional fused deposition modeling 3D printers, in order to allow simple fabrication and replacement of parts. In this paper design of the CORA hand is presented, focusing on specific design solutions adopted for improving robustness of the final 3D printed parts and for obtaining compliance in interaction with the environment. A prototype of the CORA hand was built and experimentally tested in terms of grasping capabilities, measuring contact forces and the distributed grasping pressure. Compliance introduced by soft polymer links was evaluated with finite element method simulation and experimental bending tests. A collision test evidenced robustness of the finger mechanism and transmission to pronounced passive deformations, induced by lateral contacts possibly occurring in common manipulation tasks.

The development of a conical screw-based extrusion deposition system and its application in fused deposition modeling with thermoplastic polyurethane

Purpose This paper aims to develop an integrated and portable desktop 3D printer using direct extruding technology to expand applied material field. Different from conventional fused deposition modeling (FDM) which uses polymer filaments as feedstock, the developed system can fabricate products directly using polymer pellets. And its printing properties are also investigated. Design/methodology/approach A conical screw-based extrusion deposition (CSBED) system was developed with a large taper conical screw to plasticize and extrude fed materials. The 3D printer was developed with assistance of precision positioning and controlling system. Biocompatible thermoplastic polyurethane (TPU) pellets were selected as raw materials for experiments. The influences of four processing parameters: nozzle temperature, fill vector orientation, layer thickness and infill density on the product’s internal structure and tensile properties were investigated. Findings It is concluded that the customized system has a high manufacturing accuracy with a diminutive global size and is suitable for printing soft materials such as TPU. Theoretical calculation shows the developed conical screw is more effective in plasticizing and extruding compared with conventional screw. Printed samples can achieve applicable tensile properties under harmonious parameter cooperation. Deposited materials are found to have voids among adjacent roads under unbefitting parameters. Originality/value The developed system efficiently improves material limitations compared to commercial FDM systems and exhibits great potential in medical field because soft materials such as biocompatible TPU pellets can be directly used.

Mechanical and self-monitoring behaviors of 3D printing smart continuous carbon fiber-thermoplastic lattice truss sandwich structure

A novel method for manufacturing smart continuous carbon fiber (CCF)-thermoplastic lattice truss sandwich structures (LTSSs) is presented in this study, combining the conventional fused deposition modeling (FDM) technique and the free-hanging three-dimensional (3D) printing technique. Self-monitoring of LTSSs is achieved by measuring the fractional change in electrical resistance (ΔR/R0) of the LTSSs. Monotonic out-of-plane compression test and cyclic loading test are carried out to investigate the mechanical properties, failure modes and self-monitoring capacity of the printed LTSSs. Results show that the LTSSs with truss inclination angle of 50° have an optimal compressive strength with a value of 1.236 ± 0.063 MPa, while LTSSs with truss inclination angle of 60° have an optimal compressive modulus with a value of 17.134 ± 1.92 MPa. A bilinear relationship between ΔR/R0 and stain during the whole loading process is observed, indicating that ΔR/R0 can be used to sense the compressive strain, stress and predict the damage. Matrix fracture, Euler buckling, as well as carbon fiber debonding are found within damaged LTSSs using X-ray tomography. Generally, the results indicate that the LTSSs have superior mechanical properties and self-monitoring capacity, which can help to promote the smart LTSSs applications in many engineering fields, such as aerospace and automotive industry.

Additive manufacturing and mechanical properties of lattice-curved structures

Purpose The purpose of this paper is to study the feasibility of the fabrication of circle arc curved-layered structures via conventional fused deposition modeling (FDM) with three-axis machines and to identify the main structural parameters that have an influence on their mechanical properties. Design/methodology/approach Customized G-codes were generated via a script developed in MATLAB. The G-codes contain nozzle trajectories with displacements in the three axes simultaneously. Using these, the samples were fabricated with different porosities, and their influence on the mechanical responses evaluated via tensile testing. The load-displacement curves were analyzed to understand the structure-property relationship. Findings Circled arc curved-layered structures were successfully fabricated with conventional three-axis FDM machines. The response of these curved lattice structures under tensile loads was mapped to three main stages and deformation mechanisms, namely, straightening, stretching and fracture. The micro-structure formed by the transverse filaments affect the first stage significantly and the other two minimally. The main parameters that affect the structural response were found to be the transverse filaments, as these could behave as hinges, allowing the slide/rotation of adjacent layers and making the structure more shear sensitive. Research limitations/implications This paper was restricted to arc-curved samples fabricated with conventional three-axis FDM machines. Originality/value The FDM fabrication of curved-structures with controlled porosity and their relation to the resulting mechanical properties is presented here for the first time. The study of curved-lattice structures is of great relevance in various areas, such as biomedical, architecture and aerospace.

Electroless Deposition-Assisted 3D Printing of Micro Circuitries for Structural Electronics.

Three-dimensional (3D) printing is a next-generation free-form manufacturing technology for structural electronics. The realization of structural electronic devices necessitates the direct integration of electronic circuits into 3D objects. However, creating highly conductive, high-resolution patterns in 3D remains a major challenge. Here, we report on a metallic 3D printing method that incorporates electroless deposition (ELD) into the direct ink writing method. Our approach consists of two steps: (1) direct ink writing of catalyst microstructures with a functional catalyst ink containing Ag ions and (2) ELD of Cu onto the printed catalyst structures. High-quality, stable Cu 3D printing is achieved through the design of the Ag catalyst ink; hydroxypropyl cellulose is added as both a rheological modifier (printing) and dissolution inhibitor (ELD). As a result, various two-dimensional (2D) and 3D Cu micro circuitries with high conductivity (∼65% of bulk) can be directly integrated onto 3D plastic substrates without the need for high-temperature annealing. A hybrid strategy that combines ELD-assisted 3D printing and conventional fused deposition modeling enables full fabrication of structural electronic devices. This 3D printing strategy can be a low-cost and facile method for obtaining highly conductive metallic 2D and 3D microstructures in structural electronics.

Controlling localised properties in fused deposition modelling parts: A feasibility study

Recent advancement in additive manufacturing (AM) enables us to make functional prototypes with the highest accuracy. Among various AM techniques, fused deposition modeling (FDM) is most popular due to its ability to make a complex shape in minimum time and least cost. However, the strength of the parts fabricated with FDM is always of primary concern so present approach provides a way to control localized mechanical property in FDM parts. Model of a 3D object is bifurcated into various subparts by incorporating stress data. All subparts are fabricated by using appropriate process parameters suited to their stress value. As the process parameters have a prominent effect on the strength of the part, hence the part fabricated contains better strength compared to conventional FDM approach.

Highly Loaded Graphite Composite PLA-Based Filaments for Lithium-Ion Battery 3D-Printing

Actual parallel-plate architecture of lithium-ion batteries consists in lithium ion diffusion in one dimension between the electrodes. To achieve higher performances in terms of specific capacity and power, configurations enabling lithium ion diffusion in two or three dimensions have been considered (1-5). With a view to build these complex 3D battery architectures avoiding the electrodes interpenetration issues, this work was focused on the Fused Deposition Modeling (FDM). In this presentation, the formulation and characterization of a 3D-printing graphite/polylactic-acid (PLA) filament, specially designed to be used as negative electrode in a lithium-ion battery, and to feed a conventional FDM 3D-printer will be described (6). Graphite loading into the produced filament was increased as high as possible (up to 62.5%wt) to enhance the electrochemical performances while maintaining sufficient mechanical strength to be printed. Formulation process is displayed in Fig. 1a. With such a high ratio of active material, the graphite/PLA filament was found to be very brittle. To overcome this problem, a plasticizer has been added to the PLA matrix to improve its ductility and decrease its stiffness. Influence of the amount of various plasticizers such as propylene carbonate (PC), poly(ethylene glycol) dimethyl ether average Mn~2000 (PEGDME2000), poly(ethylene glycol) dimethyl ether average Mn~500 (PEGDME500) and acetyl tributyl citrate (ATBC) was investigated by performing both differential scanning calorimetry and tensile mechanical tests. On the other hand, printability behavior of the extruded composite filaments was tested by using a commercially available 3D printer. From the optimized plasticizer composition, two-dimensional discs but also high resolution complex three-dimensional structures, such as a semi-cube lattice and a “3Dbenchy” boat, were successfully 3D-printed. Finally, considering this optimized composite, an in-depth study was carried out to identify the electronic percolation (Fig. 1b) and electrochemical impact of carbon black SuperP and carbon nanofibers as conductive additives; electrical conductivities were determined from impedance measurements performed at various stabilized temperatures ranging from 20ºC to 50°C and, in parallel, capacity retention was investigated in detail at different current densities after the different elaboration steps (film before extrusion and disc after printing). Significant progress has been achieved regarding the capacity retention as compared to Foster et al. (7) who was the first group to use FDM technology to 3D-print a negative electrode disc. They were aware that the low specific capacity values reported (15.8 mAh.g-1 at current density of 10 mA.g-1) were unfortunately caused by the use of a filament containing only 8%wt of graphene as active material and 92%wt of PLA. In this work, by increasing the graphite loading up to 62.5%wt, a reversible capacity of 201 mAh.g- 1 at current density of 4 mA.g-1 was achieved for the 3D-printed negative electrode disc by using the most printable filament (Fig. 1c).

A 4-Axis Technique for Three-Dimensional Printing of an Artificial Trachea.

Several types of three-dimensional (3D)-printed tracheal scaffolds have been reported. Nonetheless, most of these studies concentrated only on application of the final product to an in vivo animal study and could not show the effects of various 3D printing methods, materials, or parameters for creation of an optimal 3D-printed tracheal scaffold. The purpose of this study was to characterize polycaprolactone (PCL) tracheal scaffolds 3D-printed by the 4-axis fused deposition modeling (FDM) method and determine the differences in the scaffold depending on the additive manufacturing method. The standard 3D trachea model for FDM was applied to a 4-axis FDM scaffold and conventional FDM scaffold. The scaffold morphology, mechanical properties, porosity, and cytotoxicity were evaluated. Scaffolds were implanted into a 7 × 10-mm artificial tracheal defect in rabbits. Four and 8weeks after the operation, the reconstructed sites were evaluated by bronchoscopic, radiological, and histological analyses. The 4-axis FDM provided greater dimensional accuracy and was significantly closer to CAD software-based designs with a predefined pore size and pore interconnectivity as compared to the conventional scaffold. The 4-axis tracheal scaffold showed superior mechanical properties. We suggest that the 4-axis FDM process is more suitable for the development of an accurate and mechanically superior trachea scaffold.