RepRap Research Articles

INVESTIGATION ON DIMENSIONAL ACCURACY OF ADDITIVE MANUFACTURED SAMPLES

Fused deposition modelling (FDM) is a typical 3D printing process. Some benefits of FDM-printed components are durability, mechanical property stability, and the quality of the parts. However, it has several drawbacks, such as the emergence of seamlines between layers and the creation of extra material residue on the surface of the printed object, which compromises the dimensional accuracy of the printed part. When making pieces that fit correctly, the dimensions of 3D-printed components must be accurate. This article discusses the dimensional accuracy of 3D-printed components created using an open-source FDM 3D printer. The filament material for printing the test samples is stainless steel, ABS and tough PLA. The test samples were printed three times each and examined using a coordinate measuring machine (CMM). The geometries measured and compared between the three printed sample materials are the thickness, corner radius, angle, perpendicular, hole diameter, and flatness. The result shows that the printed samples could not achieve 100% dimensional accuracy, with stainless steel having the highest accuracy ranging from 99 - 98%. The data of stainless steel were then compared side by side with Tough PLA and ABS, where the accuracy of stainless steel is similar to ABS while PLA has the lowest accuracy. The accuracy of the stainless-steel specimen was then analysed and compared to tough PLA and ABS to identify the printing accuracy of the stainless-steel specimen, which is relatively new.

High stiffness 3D-printed continuous pitch carbon fiber reinforced polymer composites

This study presents a method for 3D printing very high stiffness pitch-based carbon fiber (CF) reinforced polylactic acid (PLA) composites using a modified open-source 3D printer. The fused filament fabrication (FFF) technique was used to fabricate the samples with alternating layers of PLA and PLA-coated pitch CF. The tensile Young’s modulus of the 3D-printed composite samples was measured to characterize the effect of different grades and volume fractions of pitch CF on the behaviour of the printed composites. Three grades of pitch CF which have different Young’s modulus were used with volume fractions ranging from 2.4 to 8.4%. Tensile tests showed that the K1392U CF reinforced composite with a 7.3% volume fraction demonstrated the highest improvement in Young’s modulus of 850% compared to neat 3D-printed PLA. This improvement is notably higher than any previous 3D-printed carbon-based composites at a relatively low volume fraction of CF. Statistical analysis showed increased Young’s modulus in all of 3D-printed composite samples tested. The experimental values were compared to the Halpin-Tsai model and suggest that some degree of fibre breakage occurred during the 3D printing process owing to the relative stiffness of the pitch-based fibers. Future directions and suggestions for process improvements are discussed.

A Comparative Investigation of the Reliability of Biodegradable Components Produced through Additive Manufacturing Technology.

Using the linear elastic finite element method, we investigated how defects significantly influence the integrity of 3D-printed parts made from biodegradable material by experimental techniques and numerical simulations. A defective flaw was incorporated into the tensile test dog-bone sample using Computer-Aided Design and processed by slicing software. Three distinct raster angles examine two sets of samples, one featuring intact specimens and the other with the introduced defects. An open-source 3D printer was used to fabricate both sets of samples, utilizing biodegradable PLA material. In finite element analysis, we employed a highly detailed model that precisely accounted for the geometry and dimensions of the extruded 3D-printed filament, accurately replicating the actual configuration of the 3D-printed samples to an extent. Our study involved a thorough comparative analysis between the experimental results and the FEA simulations. Our findings uncovered a consistent trend for the intact and defective samples under tensile load. Specifically, in the intact case, the samples with a zero-degree raster orientation presented the highest resistance to failure and displayed minimal elongation. Remarkably, these conclusions paralleled our observations of the defective samples as well. Finite element analysis revealed that the stresses, including Principal, Max shear, and Von Mises, were remarkably higher at the 3D-printed samples' outer surface than the inner layers, reflecting that the failure starts at the outer surface since they exceeded the theoretical values, indicating a significant discrepancy between the simulated and anticipated values.

Design, testing, and application of an open-source powder material extrusion 3D printer

Powder material extrusion (PME) additive manufacturing (AM) is a convenient and practical method to study novel materials by circumventing the need for filamentation or compounding of materials. Avoiding additional processing steps can be an enabler for research with exploratory materials or those that otherwise display thermal instabilities. In this work, we present the design, development, and testing of an open-source PME printer. The open-source PME 3D printer achieves print quality on par with commercial material extrusion 3D printers in terms of dimensional accuracy, print quality, and mechanical performance. Additionally, we demonstrate this system to be versatile and robust through printing of recycled materials, polymer composites, polymer blends, and functional polymers with thermally sensitive moieties. The broad range of build materials illustrates the diverse capabilities accessible with this system, which enabled access to properties and functions such as phosphorescence, ferromagnetism, shape memory, and mechanochromism. By improving the accessibility of PME AM and demonstrating its versatility, we hope to enable others to explore novel material systems.

Affordable and reliable three-dimensional printing: a prospective study of seven distal radius fractures

Purpose: Three-dimensional (3D) printing is now widely available, and its potential applications to surgery are limitless. However, 3D printing is presently performed at only a few large institutions. We developed a 3D printing workflow using an affordable 3D printer and open-source 3D printing software. We tested whether this combination could produce a model that reliably reflects real bone. Methods: We performed a prospective study with a target sample size of seven. Patients with distal radius fractures were enrolled from October 2021 to February 2022. The 3D-printed models of the fractures were produced using open-source software (3D Slicer [Surgical Planning Laboratory, Harvard Medical School] and Cura [Ultimaker]) and a $600 printer. The anterior-to-posterior (AP) and radial-to-ulnar (RU) widths of the fracture sites were measured on computed tomography (CT) images, in 3D printed models, and in real bones (during surgery). Surgery was simulated using the 3D models; the locations and profiles of implants were compared to those placed during real surgery, which was performed without simulation data.Results: The fracture AP and RU widths did not differ significantly among the CT, 3D model, and real bone measurements. Interclass correlation coefficients indicated that the measurements were reliable (0.943 [p<0.001] and 0.917 [p<0.001], respectively). When the implant profiles of the simulations and surgical procedures were compared, only the most distal (radial) screws were significantly longer in the simulations (p=0.016). The plate location also differed significantly (p=0.043). Conclusions: Our 3D printing workflow is affordable yet produces reliable bone models.

Melt Electrowriting of Nylon-12 Microfibers with an Open-Source 3D Printer.

This study demonstrates how either a heated flat or cylindrical collector enables defect-free melt electrowriting (MEW) of complex geometries from high melting temperature polymers. The open-source "MEWron" printer uses nylon-12 filament and combined with a heated flat or cylindrical collector, produces well-defined fibers with diameters ranging from 33±4 to 95±3µm. Processing parameters for stable jet formation and minimal defects based on COMSOL thermal modeling for hardware design are optimized. The balance of processing temperature and collector temperature is achieved to achieve auxetic patterns, while showing that annealing nylon-12 tubes significantly alters their mechanical properties. The samples exhibit varied pore sizes and wall thicknesses influenced by jet dynamics and fiber bridging. Tensile testing shows nylon-12 tubes are notably stronger than poly(ε-caprolactone) ones and while annealing has limited impact on tensile strength, yield, and elastic modulus, it dramatically reduces elongation. The equipment described and material used broadens MEW applications for high melting point polymers and highlights the importance of cooling dynamics for reproducible samples.

Conceptual Design and Numerical Validation of a Carbon-Based Ink Injector.

This paper shows the design of an injector, using carbon nanotubes as inkjet material, implemented in a 3D printer. According to the available literature, few injectors are capable of depositing material. Due to the lack of information, the central part of this research is to develop a suitable device for ink injection that is capable of applying the Fused Deposition Modeling (FDM) method to print nanomaterial ink. The injector was designed using a CAD program based on an open-source desktop 3D printer, which allows it to be modified according to the needs of the injector. This prototype was manufactured in aluminum alloy 7075T6. Computational fluid dynamics (CFD) were carried out to analyze the behavior of the fluid when it passes through the injector, obtaining parameters such as pressure, velocity, and vorticity. An experimental matrix of the injector operation was carried out to achieve an adequate printing speed. The results show that the optimum speed was 250 ms, considering that a temperature of 100 °C is needed in the heated bed to dry the ink so that it does not undergo expansion.

Exploring Open-Source 3D Printing as a Transformative Design Tool

My practice explores how to transfer my design knowledge of embroidery and print into 3D printing technologies and software. My Doctoral practice-based research explores the rationale behind using open-source, low-cost 3D printing technologies and software, which enabled me to change, remix and use the 3D printer as a flexible design tool like a sewing machine. The research aims to investigate the digitalisation of traditional textile craft techniques to produce a new taxonomy of design applications. I have produced a collection of 3D-printed embellished textiles demonstrating my practice-based re­search's ongoing outcomes. By engaging with online communities and Open-Source Technologies, I have de­vel­oped the skills to apply my specialist knowledge to this alternative technology to translate and interpret traditional textile and manipulation techniques. The exhibition will showcase these outcomes and demonstrate the opportunities within the fashion, textiles and costume industries. The post-production processes engage with my specialist background knowledge of print and dye techniques.

Implementation of 3D printing in an open-source solution in an academic library

With the RepRap project (open-source 3D printer), the possibility of access to rapid prototyping became available for retail customers. From that moment, the market was created for the development of open-source technologies to support 3D printing at each stage of the process. Consequently, several software and devices for 3D printing have been created. This paper confirms the idea that 3DP can be implemented in academic libraries as an OS solution with the benefit of ensuring low costs while maintaining sufficient accuracy. In addition, it explains how to deploy these printers, either partially or fully, and the specific open-source software and hardware tools that are usually employed in these kinds of libraries.The article is based on the author's empirical experience while conducting classes with students in 3D printing and open-source technology and operating the 3DP laboratory at the Maria Curie-Skłodowska University in Lublin, Poland. Additional data were gleaned from 114 public and private university libraries in the USA offering 3D printing services.

Effect of process parameters on performances measured in filament and pellets-based additively manufactured parts

Among all the additive manufacturing (AM) technologies, the material extrusion-based AM is the most popular, and widely used for prototyping, rapid tooling, and direct part production in the current scenario. In material extrusion AM (MEAM), a solid form of material is converted to a semi-molten form and extruded out of a nozzle to deposit in a layer-by-layer manner. Nowadays MEAM three-dimensional (3D) printers are very popular among different application sectors. This motivates us to develop various commercial as well as open-source entry-level 3D printers such as the development of filament extruder 3D printers, pellet extruder 3D printer, or a combination of both. However, to develop or operate these printers, preliminary knowledge of various extrusion parameters is required to obtain the desired quality in the fabricated parts. Therefore, an initial attempt has been made to provide information related to various extrusion parameters such as definition, working range, and the effect of these parameters on performance measured. The impact of process parameters on the performance of either filament extrusion AM or pellet/granules extrusion AM has only been investigated in the studies available in the literature. However, this study provides a comprehensive review of the effects of process parameters on performance measurements for both types of extrusion-based AM processes. In this research work, along with a detailed review of previous works, a study of various process parameters, modeling, and methodology has been provided. The statistical modeling approach, histogram normal plots have been provided along with mean, standard deviation, and percentage to decide the optimum process parameters based on data available in the existing literature.

COMPARATIVE ANALYSIS ОF GEOMETRIC DEVIATIONS IN CONTACT MEASURING INSTRUMENTS FOR CONTROL AND LASER CONTACTLESS SCANNING

The factors affecting the dimensional accuracy of 3D scanning using a measuring arm with an integrated scanner and a custom open source 3D printer using FDM technology are researched in this paper, with the purpose of isolating and reducing the sources of errors affecting the results. A consumer 3D printer is analyzed in terms of achieving accurate physical dimensions, consistent shapes, and predictable surface coverage.

Tribological and mechanical properties of fabricated soft materials with a podium mesostructured

In this paper, the sliding structure morphology, mechanical and tribological behavior of thermoplastic polyurethanes (TPU) under different conditions were studied. The coefficient of friction of TPU stabilizes rapidly at relatively low values and the wear rate increased. High load conditions significantly improved TPU's coefficient of friction and wear rate. However, a high sliding speed was helpful to form a transfer flimsy. Therefore, the coefficient of friction and wear rate of TPU were reduced at higher sliding speeds. The morphology of the wear surface of TPU indicated that the main wear process was viscous wear and wears fatigue under dry and sliding conditions. Using open-source 3D printer is common to use a series of fillers mode and density to reduce time and consumption. Involving the same FDM technique, it is an important to evaluate its strength with this technology. Herein, the effects of more adjustable variables, such as frequencies, infill patterns, density and loads, has been evaluated in detail.

Open-Source Designs for Distributed Manufacturing of Low-Cost Customized Walkers

To improve accessibility, this article describes a static, four-legged walker that can be constructed from materials and fasteners commonly available from hardware stores coupled by open-source 3D-printed joints. The designs are described in detail, shared under an open-source license, and fabricated with a low-cost open-source desktop 3D printer and hand tools. The resulting device is loaded to failure to determine the maximum load that the design can safely support in both vertical and horizontal failure modes. The experimental results showed that the average vertical failure load capacity was 3680 ± 694.3 N, equivalent to 375.3 ± 70.8 kg of applied weight with the fractured location at the wood dowel handlebars. The average horizontal load capacity was 315.6 ± 49.4 N, equivalent to 32.2 ± 5.1 kg. The maximum weight capacity of a user of 187.1 ± 29.3 kg was obtained, which indicates that the open-source walker design can withstand the weight requirements of all genders with a 95% confidence interval that includes a safety factor of 1.8 when considering the lowest deviation weight capacity. The design has a cost at the bottom of the range of commercial walkers and reduces the mass compared to a commercial walker by 0.5 kg (19% reduction). It can be concluded that this open-source walker design can aid accessibility in low-resource settings.

Effect of ultrasonic vibration on the mechanical properties of 3D printed acrylonitrile butadiene styrene and polylactic acid samples

Fused deposition modeling (FDM) is an extrusion-based AM process that is widely used due to its cost-effectiveness and user friendly. However, FDM also has some limitations such as the appearance of seam lines between layers and the production of excess material residue leading to poor surface finish, poor bonding between layers and porosity. This paper presents the findings on the application of ultrasonic vibration in an open-source FDM 3D printer to investigate its effect on the mechanical properties and microstructure of acrylonitrile butadiene styrene (ABS) and Polylactic Acid (PLA) samples. Two units of ultrasonic piezoelectric transducer were clamped horizontally on the surface of the 3D printer platform. The ultrasonic vibration was transmitted directly to the platform while the sample received vibration with a specific frequency while the printing process commences. Two process parameters, namely build orientation and ultrasonic vibration were selected to analyze their significance and optimization on the mechanical properties and the microstructure of the printed samples. High compressive and low surface roughness are required to have the best properties for the printed sample. Therefore, the optimization parameters are performed with these settings where the compressive strength is maximized and the surface roughness is minimized. The result shows that the overall compressive strength in ABS and PLA samples created in the Z-axis orientation is higher than in the X-axis orientation. However, the compressive strength of ABS and PLA samples is not much different after the ultrasonic vibration was applied during the printing process. The microstructure analysis shows that bonding between the layers is similar when applying ultrasonic vibration for both ABS and PLA samples. Furthermore, the result indicates that the surface roughness increased at 10 kHz and then decreased or became smoother at 20 kHz for both ABS and PLA material samples. The analysis shows that the build orientation significantly affects the compressive strength in ABS and PLA samples. However, the ultrasonic vibration has no considerable impact. In surface roughness, the build orientation and ultrasonic vibration significantly affect ABS samples. However, the PLA samples are only slightly affected. The optimum parameters for both materials are found where Z-axis orientation and 0 kHz of the ultrasonic vibration samples gave the best compressive strength and surface roughness value.

Design and Print Terahertz Metamaterials Based on Electrohydrodynamic Jet

Terahertz metamaterials are some of the core components of the new generation of high-frequency optoelectronic devices, which have excellent properties that natural materials do not have. The unit structures are generally much smaller than the wavelength, so preparation is mainly based on semiconductor processes, such as coating, photolithography and etching. Although the processing resolution is high, it is also limited by complex processing, long cycles, and high cost. In this paper, a design method for dual-band terahertz metamaterials and a simple, rapid, low-cost metamaterial preparation scheme based on step-motor-driven electrohydrodynamic jet technology are proposed. By transforming an open-source 3D printer, the metamaterial structures can be directly printed without complex semiconductor processes. To verify effectiveness, the sample was directly printed using nano conductive silver paste as consumable material. Then, a fiber-based multi-mode terahertz time-domain spectroscopy system was built for testing. The experimental results were in good agreement with the theoretical simulation.

Particle Swarm Optimization of Printing Parameters for Open-source TIG-based Metal 3D Printing

Proprietary metal 3D printing is still relegated to relatively expensive systems that have been constructed over years of expensive trial-and-error to obtain optimum 3D printing settings. Low-cost open-source metal 3D printers can potentially democratize metal additive manufacturing; however, significant resources are required to redevelop optimal printing parameters for each metal on new machines. In this study, the particle swam optimization (PSO) experimenter, a free and open-source software package, is utilized to obtain the optimal printing parameters for a tungsten inert gas-based metal open source 3D printer. The software is a graphical user interface implementation of the PSO method and is designed specifically for hardware-in-loop testing. It uses the input of experimental variables and their respective ranges, and then proposes iterations for experiments. A custom fitness function is defined to characterize the experimental results and provide feedback to the algorithm for low-cost metal additive manufacturing. Four separate trials are performed to determine the optimal parameters for 3D printing. First, an experiment is designed to deposit and optimize the parameters for a single line. Second, the parameters for a single-layer plane is optimized experimentally. Third, the optimal printing parameters for a cube is determined experimentally. Fourth, the line optimization experiment is revised and reconducted using different shield gas parameters. The results and limitations are presented and discussed in the context of expanding wire arc additive manufacturing to more systems and material classes for distributed digital manufacturing.

HistoEnder: A 3D printer-based histological slide autostainer that retains 3D printer functions

Automated microscope slide stainers are usually very expensive and unless the laboratory performs heavy histological work it is difficult to justify buying a 2000-10000€ machine. As a result, histology and pathology labs around the world lose thousands of working hours for following procedures that could be easily automated. Herein, we propose a simple modification of an open-source 3D printer, the Creality Ender-3, into an automated microscope slide autostainer, the HistoEnder. The HistoEnder is cheap (less than 200€), modular, and easy to set up, with only two 3D-printed parts needed. Additionally, the 3D printer retains its full functionality, and it can be reverted back into 3D printing in less than 1 min. The g-code associated with the procedure is extremely simple, and can be written by anyone. The HistoEnder can also be used in chemistry and material science laboratories for automating surface modifications and dip coating.

Tracing sustainable production from a degrowth and localisation perspective: A case of 3D printers

An emerging commons-oriented mode of production that combines globally accessible knowledge with distributed manufacturing has recently been presented as a better fit for sustainable degrowth and localisation, compared to incumbent practices. To tentatively test this potential we select the case of 3D printers. The production of 3D printers varies within a spectrum from proprietary and industrially produced to open-source and locally manufactured. We compare different 3D printers within this spectrum, adopting a values-based life cycle analysis tool that allows for a critical evaluation of the sustainability of 3D printers from a degrowth perspective. An emphasis on the prospects for sustainable localisation is given at each life cycle stage. We find significant advantages of open-source 3D printers in terms of education, experimentation and maintenance, and enhanced conviviality in case parts of their manufacturing is localised. Still, to a large extent their manufacturing process remains a highly centralised process, hindering additional benefits, and coherence with sustainable degrowth and localisation. We conclude with insights on how openness in terms of materials production and proper documentation of the manufacturing process, as well as a multi-level organisation for local production could lead to more sustainable practices.

Effect of fiber content and plasticizer on mechanical and joint properties of carbon fiber powder reinforced PLA manufactured by 3D printing process

This study investigates the mechanical and joint properties of the carbon fiber powder (CFP) reinforced polylactic acid (PLA) manufactured by 3D printing process. Composite filaments with various contents of CFP (5 wt.%, 10 wt.% and 15 wt.%) were prepared using a single screw extruder. Adherends and tensile test specimens were printed by an open-source 3D printer. Polyethylene oxide (PEO) was used as a plasticizer to improve the ductility of the PLA and PLA/CFP composite. Experimental results revealed that the CFP considerably improved the mechanical properties and the joint strengths of the composite specimens. Incorporating PEO into the blends enhanced ductility for both tensile and joint specimens but reduced strength. The SEM images showed that the fiber/matrix adhesion is weak. However, the parallel orientation of the fibers to the load direction together with their uniform distribution in the matrix increased the mechanical properties of the composites. SEM observations also showed that the addition of PEO caused porous matrix structure which is responsible for the increase in ductility of the PLA and its composites. Global yielding (G.Y) criterion was used to predict the joint failure loads and a comparison was made between experimental and predicted failure loads. The comparisons showed that the G.Y criterion over-predicted the failure loads. The minimum and maximum difference between experimental and predicted failure loads were 12.96% and 28.10%, respectively. At last, recommendations for further studies were also presented.

Waste Plastic Direct Extrusion Hangprinter

As the additive manufacturing industry grows, it is compounding the global plastic waste problem. Distributed recycling and additive manufacturing (DRAM) offers an economic solution to this challenge, but it has been relegated to either small-volume 3D printers (limiting waste recycling throughput) or expensive industrial machines (limiting accessibility and lateral scaling). To overcome these challenges, this paper provides proof-of-concept for a novel, open-source hybrid 3D printer that combines a low-cost hanging printer design with a compression-screw-based end-effector that allows for the direct extrusion of recycled plastic waste in large expandable printing volumes. Mechanical testing of the resultant prints from 100% waste plastic, however, showed that combining the challenges of non-uniform feedstocks and a heavy printhead for a hangprinter reduced the strength of the parts compared to fused filament fabrication. The preliminary results are technologically promising, however, and provide opportunities to improve on the open-source design to help process the volumes of waste plastic needed for DRAM to address the negative environmental impacts of global plastic use.