Commercial Filament Research Articles

Material extrusion‐based additive manufacturing of polypropylene: A review on how to improve dimensional inaccuracy and warpage

ABSTRACTMaterial extrusion‐based additive manufacturing (ME‐AM) is an emerging processing technique that is characterized by the selective deposition of thermoplastic filaments in a layer‐by‐layer manner based on digital part models. Recently, it has attracted considerable attention, as this technique offers manifold benefits over conventional manufacturing technologies. However, to meet the challenges of complex industrial applications, certain shortcomings of ME‐AM still need to be overcome. A case in point is the limited amount of semicrystalline thermoplastics, which are still not established as reliable, commercial filament materials. Particularly, polypropylene (PP) offers attractive properties that are unique among the ME‐AM material portfolio. This review describes the current approaches of fabricating PP components by ME‐AM. Both commercial and scientific strategies to make PP 3D‐printable are elaborated and compared. As dimensional issues are especially problematic for PP, a comprehensive section of this review focuses on the strategies developed for mitigating warpage for PP parts fabricated by ME‐AM. © 2019 The Authors.Journal of Applied Polymer Sciencepublished by Wiley Periodicals, Inc. J. Appl. Polym. Sci.2020,137, 48545.

A feasibility study for a straightforward decoration of a 3D printing filament with graphene oxide

The modification of 3D printing filaments with specific compounds, especially nanomaterials, can be regarded as an effective approach for the fabrication of novel composite structures. For this aim, the interest for potential applications of graphene oxide is continuously growing thanks to its versatility in several technological fields ranging, e.g., from mechanical engineering and sensors development to bioengineering. The intrinsic properties of this 2D carbon nanomaterial joined to the potential of 3D printing can pave the way to different approaches for designing and manufacturing ad hoc components. The present study shows a straightforward method to cover a commercial polymeric filament with graphene oxide to be subsequently processed into a testing structure by fused deposition modeling. The experimental characterization was carried out to assess the reliability of the process with the aim to evaluate the presence, the role and the distribution of the graphene oxide on the polymeric surface.

Mechanical Properties and Applications of Recycled Polycarbonate Particle Material Extrusion-Based Additive Manufacturing.

Past work has shown that particle material extrusion (fused particle fabrication (FPF)/fused granular fabrication (FGF)) has the potential for increasing the use of recycled polymers in 3D printing. This study extends this potential to high-performance (high-mechanical-strength and heat-resistant) polymers using polycarbonate (PC). Recycled PC regrind of approximately 25 mm2 was 3D printed with an open-source Gigabot X and analyzed. A temperature and nozzle velocity matrix was used to find useful printing parameters, and a print test was used to maximize the output for a two-temperature stage extruder for PC. ASTM type 4 tensile test geometries as well as ASTM-approved compression tests were used to determine the mechanical properties of PC and were compared with filament printing and the bulk virgin material. The results showed the tensile strength of parts manufactured from the recycled PC particles (64.9 MPa) were comparable to that of the commercial filament printed on desktop (62.2 MPa) and large-format (66.3 MPa) 3D printers. Three case study applications were investigated: (i) using PC as a rapid molding technology for lower melting point thermoplastics, (ii) printed parts for high temperature applications, and (iii) printed parts for high-strength applications. The results show that recycled PC particle-based 3D printing can produce high-strength and heat-resistant products at low costs.

Open Source Completely 3-D Printable Centrifuge

Centrifuges are commonly required devices in medical diagnostics facilities as well as scientific laboratories. Although there are commercial and open source centrifuges, the costs of the former and the required electricity to operate the latter limit accessibility in resource-constrained settings. There is a need for low-cost, human-powered, verified, and reliable lab-scale centrifuges. This study provides the designs for a low-cost 100% 3-D printed centrifuge, which can be fabricated on any low-cost RepRap-class (self-replicating rapid prototyper) fused filament fabrication (FFF)- or fused particle fabrication (FPF)-based 3-D printer. In addition, validation procedures are provided using a web camera and free and open source software. This paper provides the complete open source plans, including instructions for the fabrication and operation of a hand-powered centrifuge. This study successfully tested and validated the instrument, which can be operated anywhere in the world with no electricity inputs, obtaining a radial velocity of over 1750 rpm and over 50 N of relative centrifugal force. Using commercial filament, the instrument costs about U.S. $25, which is less than half of all commercially available systems. However, the costs can be dropped further using recycled plastics on open source systems for over 99% savings. The results are discussed in the context of resource-constrained medical and scientific facilities.

Maximization of FDM-3D-Objects Gonio-Appearance Effects Using PLA and ABS Filaments and Combining Several Printing Parameters: "A Case Study".

In order to consider 3D objects from suitable Fused Deposition Modelling (FDM) printers as prototypes for the automotive sector, this sample must be able to reproduce textural effects (sparkle or graininess) or metallic or gonio-appearance to reinforce the attractive appeal of these materials. This study worked with two different commercial filaments: grey metallic PLA (poly(lactic acid)) and ABS (acrylonitrile-butadiene-styrene copolymer) with diffractive pigments. For both materials, a statistical design of experiments (DoE) was carried out to find the printing parameters effect on the final 3D-objects gonio-appearance. The selected printing parameters were printing speed (2 levels), layer height (2 levels) and sample thickness (3 levels). Twelve smooth square objects were printed from each material. The ABS-diffractive filaments achieved the most significant flop and higher sparkle values than metallic PLA. Graininess was high when working with PLA filaments instead of ABS. Layer height was the most significant parameter to maximize PLA objects’ flop or sparkle effects. The best result was found when printing at 0.1 mm. For the ABS samples, the stronger flop and sparkle effects were achieved with the 50 mm/s printing speed, the 0.1 mm layer height and the lowest thickness level. This study shows the methodology to study the printing parameters effects and interactions to maximize the FDM-3D-objects gonio-appearance.

Three-Dimensional Printing of Magnetic Data Storage Structures

AbstractBar codes and quick response codes are the standard methods of visual data storage. These codes rely on changes in visual patterns to encode data into a binary format. Problems with these methods include limited data storage capacity and poor visual appeal in product marketing. This work examined magnetic patterns as an alternative to visual patterns as a potential means to encode data. Using magnetic patterns it is theorized that data storage capacity can be improved, while embedding the code within a tagged object. Magnetic patterns were formed using neodymium magnets, which yielded results that are similar to a bar code. Lines of high magnetic field strength followed by regions of low magnetic field strength at different spacing produced different overall magnetic patterns. Next, magnetic patterns were 3-dimensionally printed using an iron and polylactic acid commercial filament. The effect of infill density and the print line of the magnetic regions were studied by measuring the attractive force between the sample and a neodymium magnet attached to a force gauge for different print configurations. As expected the infill density of 100% had the highest force, which was roughly 330 mN, while the 10% sample had the lowest force being about 120 mN. It was expected that print line should not have an influence on magnetic force, but in this experiment magnetic regions with print lines at 0° were about 10 mN higher than samples printed at 90°. The cause of this was likely due to the printer error. Future work will study print plane, which is another processing variable in 3-dimensional printing. The target goal of matching the data storage capability of QR codes will also be work towards.

Investigating the Potential of Commercial-Grade Carbon Black-Filled TPU for the 3D Printing of Compressive Sensors.

The present research aims to exploit commercially available materials and machines to fabricate multilayer, topologically designed transducers, which can be embedded into mechanical devices, such as soft or rigid grippers. Preliminary tests on the possibility of fabricating 3D-printed transducers using a commercial conductive elastomeric filament, carbon black-filled thermoplastic polyurethane, are presented. The commercial carbon-filled thermoplastic polyurethane (TPU), analyzed in the present paper, has proven to be a candidate material for the production of 3D printed displacement sensors. Some limitations in fabricating the transducers from a 2.85 mm filament were found, and comparisons with 1.75 mm filaments should be conducted. Moreover, further research on the low repeatability at low displacements and the higher performance of the hollow structure, in terms of repeatability, must be carried out. To propose an approach that can very easily be reproduced, only commercial filaments are used.

3-D Printable Polymer Pelletizer Chopper for Fused Granular Fabrication-Based Additive Manufacturing

Although distributed additive manufacturing can provide high returns on investment, the current markup on commercial filament over base polymers limits deployment. These cost barriers can be surmounted by eliminating the entire process of fusing filament by three-dimensional (3-D) printing products directly from polymer granules. Fused granular fabrication (FGF) (or fused particle fabrication (FPF)) is being held back in part by the accessibility of low-cost pelletizers and choppers. An open-source 3-D printable invention disclosed here allows for precisely controlled pelletizing of both single thermopolymers as well as composites for 3-D printing. The system is designed, built, and tested for its ability to provide high-tolerance thermopolymer pellets with a number of sizes capable of being used in an FGF printer. In addition, the chopping pelletizer is tested for its ability to chop multi-materials simultaneously for color mixing and composite fabrication as well as precise fractional measuring back to filament. The US$185 open-source 3-D printable pelletizer chopper system was successfully fabricated and has a 0.5 kg/h throughput with one motor, and 1.0 kg/h throughput with two motors using only 0.24 kWh/kg during the chopping process. Pellets were successfully printed directly via FGF as well as indirectly after being converted into high-tolerance filament in a recyclebot.

Three-dimensional printing of PLA and PLA/PHA dumbbell-shaped specimens of crisscross and transverse patterns as promising materials in emerging application areas: Prediction study

This paper presents ex-ante examination of advanced polymer materials to detect defects and define and minimize the potential failure of novel polymer products before they arise. The effect of build directions on the properties of dumbbell-shaped specimens obtained by three-dimensional printing from polylactide and polylactide/polyhydroxyalkanoate commercial filaments was investigated, as well as the hydrolytic degradation of these specimens at 50 °C and 70 °C. Taking into account previous studies, we have found further dependences of the properties of 3D printed species before and during abiotic degradation from the orientation of printing. The initial assumption that only the contact time with the 3D printer platform leads to an increase in the crystalline phase during printing turned out to be insufficient. Further investigations of individual parts of the dumbbell-shaped specimens showed that the size of the specimens' surface in contact with the platform also affected the structural ordering of the material.

Polylactide (PLA) Filaments a Biobased Solution for Additive Manufacturing: Correlating Rheology and Thermomechanical Properties with Printing Quality.

Three commercial filaments for Fused Deposition Modeling (FDM) were selected to study the influence of polymer formulation on the printing quality and mechanical properties of FDM specimens. The three filaments were all based on polylactic acid (PLA) as the matrix, and they are sold as PLA filaments. The printing quality was tested by printing one complex shape with overhang features. The marked shear thinning behavior for two filaments was observed by rheology. The filaments were also studied by scanning electron microscopy and thermogravimetric analysis (TGA) to unveil their composition. The filaments with the best printing quality showed the presence of mineral fillers, which explained the melt behavior observed by rheology. The tensile testing confirmed that the filled PLA was the best-performing filament both in terms of printing quality and thermomechanical performance, with a p-value = 0.106 for the tensile modulus, and a p-value = 0.615 for the ultimate tensile strength.

Investigation of polylactide and carbon nanocomposite filament for 3D printing

Fused deposition modeling (FDM) has been used to manufacture complicated structures and robots in the past few years. However, most FDM machines do not fabricate fully functional robots that are ready for use. One of the requirements of fully functional 3D printed robots is electrical connection in some part of the printed structure. Recently, electrically conductive commercial filaments are emerging to the market, but the actual chemical compositions of the filler and host materials as well as mechanical properties are not available. This paper presents composite materials consisting of conductive carbon nanoparticles, thermoplastics, and solvents to create thin filaments for 3D printing. The mechanical and electrical properties of the filaments fabricated using a composition of 0–15% weight of carbon nanoparticles (NC) in polylactide (PLA) and dichloromethane (DCM) solvent were investigated. The DCM is used for dissolving the PLA and dispersion of the NC, which is subsequently evaporated by drying. The electrical conductivity of the composite filament is compared with commercial and academia counterparts. Possible applications of the composite materials for fabrication of electrical circuitry for 3D printed robots were also discussed.

Development of a Simple Mechanical Screening Method for Predicting the Feedability of a Pharmaceutical FDM 3D Printing Filament

PurposeThe filament-based feeding mechanism employed by the majority of fused deposition modelling (FDM) 3D printers dictates that the materials must have very specific mechanical characteristics. Without a suitable mechanical profile, the filament can cause blockages in the printer. The purpose of this study was to develop a method to screen the mechanical properties of pharmaceutically-relevant, hot-melt extruded filaments to predetermine their suitability for FDM.MethodsA texture analyzer was used to simulate the forces a filament is subjected to inside the printer. The texture analyzer produced a force-distance curve referred to as the flexibility profile. Principal Component Analysis and Correlation Analysis statistical methods were then used to compare the flexibility profiles of commercial filaments to in-house made filaments.ResultsPrincipal component analysis showed clearly separated clustering of filaments that suffer from mechanical defects versus filaments which are suitable for printing. Correlation scores likewise showed significantly greater values with feedable filaments than their mechanically deficient counterparts.ConclusionThe screening method developed in this study showed, with statistical significance and reproducibility, the ability to predetermine the feedability of extruded filaments into an FDM printer.

Recycled polyethylene terephthalate as a new FFF feedstock material

Reclaimed materials such as waste plastics can be utilized in additive manufacturing to improve the self-reliance of warfighters on forward operating bases by cutting costs and decreasing the demand for the frequent resupplying of parts by the supply chain. In addition, the use of waste materials in additive manufacturing in the private sector would reduce cost and increase sustainability, providing a high-value output for used plastics. Experimentation is conducted to process polyethylene terephthalate bottles and packaging into filament that can then be used for additive manufacturing methods like fused filament fabrication, without the use of additives or modification to the polymer. The chemistry of different polyethylene terephthalate recycled feedstocks was evaluated and found to be identical, and thus mixed feedstock processing is a suitable approach. Rheological data showed drying of the recycled polyethylene terephthalate led to an increase in the polymer’s viscosity. Thermal and mechanical properties were evaluated for filament with different processing conditions, as well as printed and molded specimens. Crystallinity ranged from 12.2 for the water cooled filament, compared to 24.9% for the filament without any active cooling. Tensile results show that the elongation to failure was similar to an injection molded part (3.5%) and tensile strength of 35.1 ± 8 MPa was comparable to commercial polycarbonate-ABS filament, demonstrating the robustness of the material. In addition, three point bending tests showed a similar load at failure for a select long-lead military part printed from the recycled filament compared to parts printed from commercial filament. Thus filament from recycled polyethylene terephthalate has the capability for replacing commercial filament in printing a diverse range of plastic parts.

Tough thiourethane thermoplastics for fused filament fabrication

ABSTRACTFused filament fabrication (FFF) is the most common form of additive manufacturing. Most FFF materials are variants of commercially available engineering plastics. Their performance when printed can widely vary, thus there is an increasing volume of research on alternative materials with thermal and mechanical performance optimized for FFF. In this work, thiol–isocyanate polymerization is used for the development of a one‐pot synthesis for polythiourethane thermoplastics for tough three‐dimensional (3D) printing applications. The thiol–isocyanate reaction mechanism allows for rapid polymer synthesis with minimal byproduct formation and few limitations on reaction conditions. The resulting elastomer has high toughness and a low melting point, making it favorable for use as a 3D printing filament. The elastomer outperforms commercial filaments in tension when printed. Considering the rapid advancement of additive manufacturing and the limitations of many engineering polymers with the 3D printing process, these results are encouraging for the development of bespoke 3D printing thermoplastics. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45574.

Metal-free current collectors based on graphene materials for supecapacitors produced by 3D printing

Supercapacitor (SC) current collectors with electrodes made of graphite oxide reduced during microwave exfoliation are produced from a commercial filament with a graphene component via layer-by-layer fusing with a 3D printer. The separator is made of a graphene oxide film. The current collectors are investigated by means of IR spectroscopy. Electrochemical tests are performed for the assembled SC that include tests of its cyclic stability up to 1000 cycles.

Additive manufacturing of multifunctional reactive materials

This paper demonstrates the ability to 3D print a fluoropolymer based energetic material which could be used as part of a multifunctional reactive structure. The work presented lays the technical foundation for the 3D printing of reactive materials using fusion based material extrusion. A reactive filament comprising of a polyvinylidene fluoride (PVDF) binder with 20% mass loading of aluminum (Al) was prepared using a commercial filament extruder and printed using a Makerbot Replicator 2X. Printing performance of the energetic samples was compared with standard 3D printing materials, with metrics including the bead-to-bead adhesion and surface quality of the printed samples. The reactivity and burning rates of the filaments and the printed samples were comparable. Differential scanning calorimetry and thermal gravimetric analysis showed that the onset temperature for the reactions was above 350°C, which is well above the operation temperature of both the filament extruder and the fused deposition printer.

Impact of DIY Home Manufacturing with 3D Printing on the Toy and Game Market

The 2020 toy and game market is projected to be US$135 billion. To determine if 3D printing could affect these markets if consumers offset purchases by 3D printing free designs, this study investigates the 100 most popular downloaded designs at MyMiniFactory in a month. Savings are quantified for using a Lulzbot Mini 3D printer and three filament types: commercial filament, pellet-extruded filament, and post-consumer waste converted to filament with a recyclebot. Case studies probed the quality of: (1) six common complex toys; (2) Lego blocks; and (3) the customizability of open source board games. All filaments analyzed saved the user over 75% of the cost of commercially available true alternative toys and over 90% for recyclebot filament. Overall, these results indicate a single 3D printing repository among dozens is saving consumers well over $60 million/year in offset purchases. The most common savings fell by 40%–90% in total savings, which came with the ability to make novel toys and games. The results of this study show consumers can generate higher value items for less money using the open source distributed manufacturing paradigm. It appears clear that consumer do-it-yourself (DIY) manufacturing is set to have a significant impact on the toy and game markets in the future.

Manufacturing and characterization of 3D printer filament using tailoring materials

In 3D printing, a good finish must be offered as product result. It needs to be solid and durable; therefore, it is desirable that the produced filament yields good final results, durable and resistant. In this project, the tailored processed filament is characterized by checking its tensile stress and comparing its results with commercial filaments. The purpose of the present work is to use and characterize the product obtained with filament extrusion equipment for 3D printers. There is a need to find an alternative to the obligation in having to buy from a supplier, a filament. It would be an achievement to obtain, in a self-sufficient way, the necessary quantity of material.

Effects of Filament Diameter Tolerances in Fused Filament Fabrication

Fused filament fabrication (FFF) is one of the most popular additive manufacturing (3D printing) technologies due to the growing availability of low-cost desktop 3D printers and the relatively low cost of the thermoplastic filament used in the 3D printing process. Commercial filament suppliers, 3D printer manufacturers, and end-users regard filament diameter tolerance as an important indicator of the 3D printing quality. Irregular filament diameter affects the flow rate during the filament extrusion, which causes poor surface quality, extruder jams, irregular gaps in-between individual extrusions, and/or excessive overlap, which eventually results in failed 3D prints. Despite the important role of the diameter consistency in the FFF process, few studies have addressed the required tolerance level to achieve highest 3D printing quality. The objective of this work is to develop the testing methods to measure the filament tolerance and control the filament fabrication process. A pellet-based extruder is utilized to fabricate acrylonitrile butadiene styrene (ABS) filament using a nozzle of 1.75 mm in diameter. Temperature and extrusion rate are controlled parameters. An optical comparator and an array of digital calipers are used to measure the filament diameter. The results demonstrate that it is possible to achieve high diameter consistency and low tolerances (0.01mm) at low extrusion temperature (180 °C) and low extrusion rate (10 in/min).

A new look at extensional rheology of low-density polyethylene

The nonlinear rheology of three selected commercial low-density polyethylenes (LDPE) is measured in uniaxial extensional flow. The measurements are performed using three different devices including an extensional viscosity fixture (EVF), a homemade filament stretching rheometer (DTU-FSR) and a commercial filament stretching rheometer (VADER-1000). We show that the measurements from the EVF are limited by a maximum Hencky strain of 4, while the two filament stretching rheometers are able to probe the nonlinear behavior at larger Hencky strain values where the steady state is reached. With the capability of the filament stretching rheometers, we show that LDPEs with quite different linear viscoelastic properties can have very similar steady extensional viscosity. This points to the potential for independently controlling shear and extensional rheology in certain rate ranges.