Fused Deposition Modeling Technology Research Articles

Improving Cooling Performance of Injection Molding Tool with Conformal Cooling Channel by Adding Hybrid Fillers.

Silicone rubber mold (SRM) is capable of reducing the cost and time in a new product development phase and has many applications for the pilot runs. Unfortunately, the SRM after injection molding has a poor cooling efficiency due to its low thermal conductivity. To improve the cooling efficiency, the thermal conductivity of the SRM was improved by adding fillers into the SRM. An optimal recipe for fabricating a high cooling efficiency low-pressure injection mold with conformal cooling channel fabricated by fused deposition modeling technology was proposed and implemented. This study proposes a recipe combining 52.6 wt.% aluminum powder, 5.3 wt.% graphite powder, and 42.1 wt.% liquid silicon rubber can be used to make SRM with excellent cooling efficiency. The price–performance ratio of this SRM made by the proposed recipe is around 55. The thermal conductivity of the SRM made by the proposed recipe can be increased by up to 77.6% compared with convention SRM. In addition, the actual cooling time of the injection molded product can be shortened up to 69.1% compared with the conventional SRM. The actual cooling time obtained by the experiment is in good agreement with the simulation results with the relative error rate about 20%.

Attempts to Diminish the Drawbacks of Polylactic Acid Designed for 3D/4D Printing Technology-Fused Deposition Modeling

In order to improve thermal behavior and dimensional strability of polylactic acid (PLA) designed both for 3D and 4D printing technology-fused deposition modeling (FDM) using a scalable procedure, the polymer was melt compounded with additives which control the morphology by crystallization and/or reinforcing. Using the formulations which provide polylactic acid (PLA) improved thermo-mechanical properties and desired dimensional stability, the new materials were shaped, on a laboratory line, as filaments for printing technology. The selected compounds were than scaled up on a 50 kg/h compounding line into granules which prove to have good shapability as filaments for printing technology (1.85 +/- 0.05 mm diameter, required ovality, good appearance and smooth surface) and performed properly at 3D printing. The obtained results proved that functional properties of PLA can be improved by various methods so that, depending on the reached performances, the new material can be converted through printing technology into items for performance applications. The novelty of the article is related to the fact that it identifies a modifying solution for controlling the morphology of a type of PLA designed for 3D printing that already has an advanced crystallinity.

Printing ionic polymer metal composite actuators by fused deposition modeling technology

ABSTRACT In this work, we printed a Nafion precursor membrane by fused deposition modeling (FDM) rapid prototyping technology and further fabricated IPMCs by electroless plating. The ion-exchange capacity of the Nafion membrane was tested, and the morphology of IPMCs was observed. The electro-mechanical properties of IPMCs under AC voltage inputs were studied, and grasping experiments were performed. The results show that the Nafion membrane after hydrolysis has a good ion-exchange ability and water-holding capacity. SEM observed that the thickness of the IPMC’s electrode layer was about 400 nm, and the platinum layer was tightly combined with the substrate membrane. When using a square wave input of 3.5 V and 0.1 Hz, the maximum current of IPMCs reached 0.30 A, and the displacement and blocking force were 7.57 mm and 10.5 mN, respectively. The new fabrication process ensures the good driving performance of the printed IPMC. And two pieces of IPMCs can capture the irregular objects successfully, indicating the feasibility of printing IPMCs by FDM technology. This paper provides a new and simple method for the fabrication of three-dimensional IPMCs, which can be further applied in flexible grippers and soft robotics.

Investigation of the physical and mechanical properties of composite materials obtained using additive technologies

The prevalence of polymers in all spheres of human life necessitates the creation of new more effective composite materials based on polymer matrices and reinforcing fillers, which by their characteristics meet the growing needs of society. In modern industry, production speeds are constantly increasing, so additive technologies are becoming a powerful alternative to traditional single and small-scale production.
 Among the existing types of additive technologies, the method of fused deposition modeling (FDM) deserves special attention, which provides an opportunity to organize production in conditions of limited material, time and human resources. As opposite to traditional production technologies, such as injection molding, FDM allows you to create products of more complex geometric shapes, using different combinations of polymer matrices and reinforcing fillers and thus create composite materials with the required physico-mechanical, rheological and other properties. At the same time, the main advantages of FDM also cause a number of serious disadvantages, such as anisotropy of the properties of finished products, printing defects that lead to increased yields of defective products, uneven physical and mechanical properties etc. In particular, the anisotropy of the properties of FDM-printed products results in significantly lower strength of the parts in the transverse direction to the 3D printing direction (strand overlay direction) compared to the longitudinal one, and the discontinuity of the reinforcing fibers in the strands of polymeric material leads to reduced strength.
 The main areas of research to modernize the process of manufacturing products on a 3D printer using the FDM method are: modernization of components and structures of 3D printers to improve the melting process and layering of materials, aimed at improving print quality and speed, as well as reducing defective yield products; improving the properties of raw materials and creating composite materials to improve the quality of finished products and their characteristics, such as electrical, chemical, mechanical, thermal, environmental, etc .; development of new biopolymers, technologies of their production and use for 3D-printing, which in the future are planned to be used in the creation of bionic parts of human bodies, etc.
 To overcome the main shortcomings of FDM technology, it is proposed to modernize the method of 3D printing and the extruder unit of the 3D printer, which allows to create composite materials directly (directly in the extruder), using different combinations of polymer matrices and solid reinforcing fibers.

Dimensional Accuracy Control and Compressive Property of Microcellular Polyetherimide Honeycomb Foams Manufactured by an In Situ Foaming Fused Deposition Modeling Technology

The microcellular honeycomb foams can be manufactured via fused deposition modeling (FDM) technology. However, the process often involves complicated pre/post‐treatment. Herein, a novel in situ foaming FDM technology is developed to efficiently fabricate the microcellular polyetherimide (PEI) honeycomb foams with various lattice structures. The extremely low gas diffusivity endows the CO2‐saturated PEI filament with a long‐time printing ability and well printing performance, which is characterized by a long printable time up to 7 days and the formation of microcellular structure within the deposited foam strands. The printed PEI foam parts possess high dimensional accuracy with a relative accuracy (δR) of 1.3–6.4% at the external regions and low internal accuracy with δR of 27.5–48.8%, resulting from the increased nozzle expansion and reduced melt viscosity. An accuracy correction based on the nozzle expansion is effective to improve the dimensional accuracy of the foam parts. The high accuracy control of macro/microstructure and the advantages of green processing and long‐time printing make the in situ foaming FDM technology show great application prospects in the fabrication of hierarchical cellular materials.

Green recycling of aluminum plastic packaging waste by solid‐state shear milling and 3D printing for thermal conductive composites

AbstractAluminum‐plastic packaging is a multilayer material composed of polymer and aluminum, which has been applied in food, medical, and other fields, due to the excellent fresh‐keeping and barrier performance. However, it is difficult to recycle aluminum‐plastic packaging waste (APPW) due to the complicated components and the low value of reclaim products. This paper reports a green way to recycle the APPW by solid‐state shear milling (S3M) technology and then fabricate APPW/expandable graphite (EG) composite parts with high thermal conductivity by fused deposition modeling (FDM) process. After the S3M treatment, the ultrafine APPW powder with the size of 7 ~ 8 um was obtained, and it showed excellent processibility and the APPW/EG composite parts were successfully processed by FDM technology. The APPW/EG three‐dimensional (3D) printed parts showed excellent mechanical and heat transfer performance along the stretch direction (0°), where the tensile strength and thermal conductivity reached 13.58 MPa and 2.71 W/mK for APPW/EG (80/20) composites, respectively, much higher than those of pure APPW composite (7.71 MPa and 0.62 W/mK). Theoretical calculations showed that the interfacial thermal resistances of APPW/EG 3D printed parts with aligned fillers were lower than other samples. Furthermore, the APPW/EG composites with 20 wt.% EG loading showed a low electrical conductivity of 10−10 S/cm because the oxidation layer was formed on the surface of Al flakes during the S3M process, which can be used in the thermally conductive insulating field. The new strategy presented in this work provides a new sight to recycle APPW for value‐add material.

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.

Tuning the structural and functional properties of HAVOH-based composites via ionic liquid tailoring of MWCNTs distribution

The structural and functional properties of polymer composite materials strictly depend on the spatial distribution of fillers, such as multiwalled carbon nanotubes (MWCNTs), inside the matrix. Herein, novel composites have been obtained by embedding MWCNTs into a modified polyvinyl alcohol (HAVOH) matrix, using the ionic liquid (IL) 1-Benzyl-3-methylimidazolium chloride (BenzImCl) as compatibilizer. The composites were prepared by solvent-wrapping carbon nanotubes onto HAVOH powders, followed by the melt-compounding approach to produce pellets for Fused Deposition Modelling technology (FDM). The efficacy of both the process and the IL on tailoring the spatial distribution of the MWCNTs into the HAVOH matrix is thoroughly studied and correlated with the electrical conductivity of the resulting composites. The sample printed by FDM, containing 6 wt % of MWCNTs and 0.6 wt% of IL exhibited a percolating morphology and led to an electrical conductivity (σ) value of 1.2*10−2 S/m. Moreover, after annealing at 220 °C for 2 h the σ value increased up to 7.9*10−1 S/m. The thermal treatment in presence of the MWCNTs also induces the formation of crosslinked HAVOH molecules changing the composites from easily soluble to completely water insoluble materials. This revealed the potential of HAVOH-based composites as raw material for FDM technology to realize post-printing cross-linkable materials.

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.

Analysis of FDM and DLP 3D-Printing Technologies to Prototype Electromagnetic Devices for RFID Applications.

In this work, the application in Radiofrequency Identification (RFID) of different additive manufacturing (AM) 3D-printing technologies is discussed. In particular, the well-known Fused Deposition Modeling (FDM) technology is compared with the promising Digital Light Processing (DLP), which is based on the photopolymerization of liquid resins. Based on the research activity of the authors on this topic, a brief introduction to the fundamentals of 3D-printing in electromagnetics as well as to the different applications of both FDM and DLP in realizing Radio Frequency (RF) devices, is firstly given. Then, a comparison of the two technologies is deeply faced. Finally, after evaluated the rugosity of substrates produced with both techniques to verify the potential impact on the design of electromagnetic structures, the two techniques are both exploited for the realization of the dielectric parts of a tunable RFID tag with unconventional shape. It consists of two elements interlinked one each other. The movement between them enables tuning of the resonance frequency as well as the impedance of the antenna. Despite the differences in terms of losses, rugosity, resolution, and dielectric constant, both techniques guaranteed satisfactory values of tag sensitivity, maximum reading range, and tunability. Nevertheless, the careful analysis of the results proposed at the end of the paper suggests how the selection of one technique over the other must be taken considering the specific application constraints.

Characterization of carbon fiber reinforced PLA composites manufactured by fused deposition modeling

Additive manufacturing (AM) is a process of producing 3D parts with complex geometries by depositing layer-by-layer and these technologies have been successfully utilized in numerous engineering application. Fused deposition modeling (FDM) is one of the most promising material extrusion based and commonly used AM technology, which is most widely used for producing thermoplastic parts for functional applications with aim of low cost, minimum wastage and simplicity of material conversion. Due to substantially inadequate mechanical performance of pure thermoplastics material, there is a need to improve the mechanical properties of FDM generated thermoplastic parts. One of the possible methods is to add the reinforcement material such as continuous carbon fiber (CCF) to the thermoplastic matrix to form continuous carbon fiber reinforced polymer composite (CCFRPC), which could be used in engineering applications. Four groups of specimens were prepared: poly-lactic acid thermoplastic (PLA), PLA with short carbon fiber (PLA-SCF), PLA printed with CCF (PLA-CCF) and PLA-SCF printed with CCF (PLA-SCF-CCF) using FDM technology. Effects on the tensile and flexural properties of specimens were experimentally investigated after FDM production process. In order to study the specimens fracture and interfacial bond of the 3D printed parts, fracture interface was observed and analyzed using optical microscope's micrograph after performing the mechanical tests.

Scale effect on the mechanical behavior of PLA specimens fabricated via Fused Deposition Modeling

Fused Deposition Modeling (FDM) is one of the most widely used additive manufacturing processes in the world. It is also a rapid prototyping process that can fabricate the physical model generated from the CAD model automatically without the usage of any tooling or fixture. In general, the mechanical properties of components produced with additive manufacturing are dependent on the geometry and the scale of the fabricated part. Any change in the geometry of the parts will influence the underlying fabrication process and inherent characteristics of the parts such as internal porosity, residual stress, etc. Therefore, it is important to understand the connection between the mechanical properties of these components and their geometry and scale of the produced parts in order to improve the design technique and applicability of the manufacturing technique. In this study, the scale effect on the mechanical performance of PLA (Polylactic Acid) specimens fabricated via FDM technology has been investigated. A total number of 15 test specimens were fabricated with three different scales, including 30%, 50%, and 100% of the size suggested in ASTM standard for tensile testing of polymers. The mechanical properties, including yield stress, ultimate tensile strength, Young’s modulus, Poisson’s ratio and elongation at failure were determined, compared, and analyzed from uniaxial tensile tests. In addition, 2D digital image correlation (DIC) method was also used to track the full-field displacement and strains on the surface of specimens. Moreover, the fracture surfaces were analyzed with the use of an optical microscope to evaluate the failure mechanisms of the tested specimens. The experimental results revealed that specimens with downscaling experience both lower ultimate tensile strength and elongation at failure. Furthermore, the standard deviation of elongation at failure increases when downscaling. This is due to the fact that first layer quality and residual stress will have more influence on the data uncertainty when the scale is lower.

STEP/STEP-NC-compliant manufacturing information of 3D printing for FDM technology

Advanced manufacturing in the context of the digital thread has mainly focused on process information related to the integration of machining processes, tools, operations, and specific manufacturing parameters. However, no unified information model has been developed to represent specific manufacturing process in 3D printing. This work therefore proposes a STEP/STEP-NC-compliant process data model to define specific application objects and entities, to model manufacturing data relationships and constraints, and to standardize process parameters through extended 3D printing concepts in fused deposition modelling (FDM). This data model describes manufacturing layers, deposition operations and process parameters in the context of the digital thread. As a special feature, manufacturing layers provide geometric information to layered operations based on STEP/STEP-NC standards for additive manufacturing (AM). Deposition operations specify the definitions of print devices or headers, header paths, FDM technology and functions, and even deposition strategy. Process parameters mainly provide process information in the FDM process. Finally, a conformance testing process is developed, focussed on manufacturing layers and header paths and by means of information exchange.

Quality Prediction of Fused Deposition Molding Parts Based on Improved Deep Belief Network.

Tensile strength, warping degree, and surface roughness are important indicators to evaluate the quality of fused deposition modeling (FDM) parts, and their accurate and stable prediction is helpful to the development of FDM technology. Thus, a quality prediction method of FDM parts based on an optimized deep belief network was proposed. To determine the combination of process parameters that have the greatest influence on the quality of FDM parts, the correlation analysis method was used to screen the key quality factors that affect the quality of FDM parts. Then, we use 10-fold cross-validation and grid search (GS) to determine the optimal hyperparameter combination of the sparse constrained deep belief network (SDBN), propose an adaptive cuckoo search (ACS) algorithm to optimize the weights and biases of the SDBN, and complete the construction of prediction model based on the above work. The results show that compared with DBN, LSTM, RBFNN, and BPNN, the ACS-SDBN model designed in this article can map the complex nonlinear relationship between FDM part quality characteristics and process parameters more effectively, and the CV verification accuracy of the model can reach more than 95.92%. The prediction accuracy can reach more than 96.67%, and the model has higher accuracy and stability.

Additive manufacturing of an automotive brake pedal by metal fused deposition modelling

This research is intended to study the possibility of implementing low-cost Additive Manufacturing (AM) technologies to produce metallic automotive brake pedal rapidly, covering the main aspects of design, material, and manufacturing. The main objective of this research is to explore new brake pedal design considering AM design freedom, parts consolidation with reduced mass, new AM material and application of metal-based AM fabrication technology. The most widely used AM technology, the Fused Deposition Modelling (FDM), has been used to produce metallic brake using the metal-polymer filaments followed by debinding and sintering processes. Finite Element Analysis (FEA) has been applied to analyze the feasibility of new brake pedal design for AM processing. The prototype of the FDM produced metal brake pedal has been physically tested to validate the FEA results and to evaluate the reliability of metal based FDM technology.

Strength produced parts by fused deposition modeling

The aim of using additive manufacturing technologies is to be able to produce a wide range of component designs on a single device, using a wide range of materials and minimizing material consumption. There are several technologies that work on different principles. The present article is focused on Fused Deposition Modeling (FDM) technology, which is focused on the application of layers of semi-molten polymer. The advantage is the lower cost for obtaining of FDM device, but also the low operation cost. The output of production are complex components designed for prototyping, but also for final use. Due to the fact that there is requirement to produce parts also for final use, it is necessary to know the strength properties of the parts after production. Because the structure of parts volume is not homogeneous, it is not possible to subject it to conventional calculations and simulations, but it is necessary to take into account the specifics that are produced during production by FDM technology. The present paper shows the results of experimental determination of the tensile strength of manufactured parts. A series of samples with different properties was used on the FDM device and the tensile strength of the components was subsequently measured. The measured values ​​were compared and evaluated.

Research of TPU Materials for 3D Printing Aiming at Non-Pneumatic Tires by FDM Method.

3D printing technology has been widely used in various fields, such as biomedicine, clothing design, and aerospace, due to its personalized customization, rapid prototyping of complex structures, and low cost. However, the application of 3D printing technology in the field of non-pneumatic tires has not been systematically studied. In this study, we evaluated the application of potential thermoplastic polyurethanes (TPU) materials based on FDM technology in the field of non-pneumatic tires. First, the printing process of TPU material based on fused deposition modeling (FDM) technology was studied through tensile testing and SEM observation. The results show that the optimal 3D printing temperature of the selected TPU material is 210 °C. FDM technology was successfully applied to 3D printed non-pneumatic tires based on TPU material. The study showed that the three-dimensional stiffness of 3D printed non-pneumatic tires is basically 50% of that obtained by simulation. To guarantee the prediction of the performance of 3D printed non-pneumatic tires, we suggest that the performance of these materials should be moderately reduced during the structural design for performance simulation.

Haptic Evaluation of 3D-printed Braille-encoded Intraoral Films

The three-dimensional (3D) printing technology has recently emerged in the pharmaceutical field, providing an array of applications for individualized dosing and elaborate formulation designs. However, an alternative asset of the 3D printing technology is the capability to imprint haptic identifiers directly onto the surface of the formulations. This approach can generate novel design concepts, that will serve specific populations for identifying the right treatment regimen, i.e., visually impaired people. Toward this direction, the fused deposition modelling (FDM) technique was investigated for manufacturing intraoral films and incorporating Braille characters on the available area. The films comprised a drug-loaded compartment and a backing layer, which are typical structural characteristics for buccal delivery. A hydrophilic polymer, i.e., hydroxypropyl methylcellulose, provided the polymer matrix for both compartments, whereas ketoprofen was incorporated in the study as model drug. The Braille-encoded texts were designed on top of the backing layer, complying with the Marburg Medium spacing convention for pharmaceutical Braille. Moreover, modifications on the standard spacing and dimension parameters were applied, to investigate the accuracy and repeatability of the FDM process. The fabricated films were subjected to a haptic evaluation study with the aid of visually impaired individuals, to assess the readability of the 3D-printed Braille-encoded text. The outcomes of the study highlighted the capacity of the FDM technology in combining novel manufacturing concepts for individualized therapies with customized services that can be provided to specific populations, as in the case of people with visual impairment.

Surface bonding of additive manufactured parts from multi-colored PLA materials

Producing Multi-Material parts via Rapid Prototyping can be an excellent solution for many applications, but also a challenging design task. Material Extrusion is suitable to use multiple materials simultaneously to generate a single component. In this article, the mechanical properties were examined of this kind of PLA component from tensile tests. To determine the adhesion relationship between two parts of the same sample made of PLA material of different colors, several test samples have been prepared with different types of contact surfaces. It has been taken into consideration and analyzed the horizontal-vertical adhesion and the contour lines of a Fused Deposition Modeling (FDM) additive process. In this article, the mechanical properties of the parts made from two different colored PLA in the same components manufactured with FDM technology were investigated, particularly the interfacial adhesion. This is a crucial step to understanding the behaviour of the Multi-Material parts.

Clinical evaluation of rapid 3D print-formed implants for surgical reconstruction of large cranial defects.

To clinically evaluate 3D print-formed implant process, using cranioplasty as a proof of concept, to examine its effectiveness and utility as a method of intraoperative implant fabrication. Twelve patients had a 3D print-formed template created for patient-specific implant manufacture. Of these patients, 10 received intraoperatively formed polymethylmethacrylate cranioplasty implants between 2013 and 2019. The 3D print-formed implant templates produced to manufacture these patient-specific implants were generated using patient computed tomography scans and 3D printed using fused deposition modelling technology. Cosmetic and functional results were determined by participating surgeons, in conjunction with a patient questionnaire. The functional results and stability of the implants were deemed to be favourable by participating surgeons. Three of the 10 patients completed a post-cranioplasty survey, all of whom judged their cosmetic results as good or excellent. At time of writing, the rate of surgical revision was zero and without clinically adverse outcomes. 3D print-formed implants are an effective method of patient-specific implant formation.