Printing Time Research Articles

Increasing resolution in additive manufacturing by using high-performance and non-toxic photoinitiating systems

Additive manufacturing technology has recently revolutionized the manufacturing industry. In particular, additive manufacturing based on photopolymerization is becoming increasingly popular owing to its ability to create complex geometries at a high resolution. In addition, the use of biocompatible and non-toxic human compounds allows this additive manufacturing to be used in obtaining implants or prostheses, among other applications. Photoinitiators play a key role in this process by initiating the polymerization reaction under the influence of light. Two-component photoinitiator systems, which include newly synthesized 1,4-benzoxazin-2-ones, have been developed to improve the quality and resolution of 3D printed objects. Spectroscopic studies and kinetic measurements were conducted using real-time Fourier transform infrared (FT-IR) spectroscopy. Moreover, various objects were printed to identify favorable substitutions and modifications that would provide the highest efficiency for additive manufacturing. The cytotoxicity of the new compounds was also investigated to assess their safety in human and environmental health. The results presented here provide a better understanding of the effect of a properly selected photoinitiating system on the printing process, which results in better resolution of the objects obtained and can significantly reduce the printing time, while the lack of demonstration of an antiproliferative effect indicates promising potential in obtaining biomaterials using 3D bioprinting techniques.

Considerations on the Design, Printability and Usability of Customized 3D-Printed Upper Limb Orthoses

This paper investigated the feasibility of using 3D printing processes, specifically material extrusion (MEX) and vat photopolymerization (DLP—Digital Light Processing), to produce customized wrist–hand orthoses. Design, printability, and usability aspects were addressed. It was found that minimizing printing time for orthoses with intricate shapes, ventilation pockets, and minimal thickness is difficult. The influence of build orientation and process parameters, such as infill density, pattern, layer thickness, and wall thickness, on printing time for ten parameter configurations of orthoses in both ready-to-use and flat thermoformed shapes was examined. The findings revealed that the optimized orientations suggested by Meshmixer and Cura (Auto-orient option) did not reliably yield reduced printing times for each analyzed orthoses. The shortest printing time was achieved with a horizontal orientation (for orthoses manufactured in their ready-to-use form, starting from 3D scanning upper limb data) at the expense of surface quality in contact with the hand. For tall and thin orthoses, 100% infill density is recommended to ensure mechanical stability and layer fill, with caution required when reducing the support volume. Flat and thermoformed orthoses had the shortest printing times and could be produced with lower infill densities without defects. For the same design, the shortest printing time for an orthosis 3D-printed in its ready-to-use form was 8 h and 24 min at 60% infill, while the same orthosis produced as flat took 4 h and 37 min for the MEX process and half of this time for DLP. Usability criteria, including perceived immobilization strength, aesthetics, comfort, and weight, were evaluated for seven orthoses. Two healthy users, with previous experience with traditional plaster splints, tested the orthoses and expressed satisfaction with the 3D-printed designs. While the Voronoi design of DLP orthoses was visually more appealing, it was perceived as less stiff compared to those produced by MEX.

Environmental Impact of Fused Filament Fabrication: What Is Known from Life Cycle Assessment?

This systematic review interrogates the literature to understand what is known about the environmental sustainability of fused filament fabrication, FFF (also known as fused deposition modeling, FDM), based on life cycle assessment (LCA) results. Since substantial energy demand is systematically addressed as one of the main reasons for ecological damage in FFF, mitigation strategies are often based on reducing the printing time (for example, adopting thicker layers) or the embodied energy per part (e.g., by nesting, which means by printing multiple parts in the same job). A key parameter is the infill degree, which can be adjusted to the application requirements while saving printing time/energy and feedstock material. The adoption of electricity from renewable resources is also expected to boost the sustainability of distributed manufacturing through FFF. Meanwhile, bio-based and recycled materials are being investigated as less impactful alternatives to conventional fossil fuel-based thermoplastic filaments.

Scanning‐Laser‐Based Microstereolithography of Microfluidic Chips with Micron Resolution

AbstractThe constant improvement of stereolithography (SL) in terms of achievable resolution and printing time has sparked high expectations that SL will enable the rapid prototyping of truly microfluidic chips with features below 100 µm. However, most commercial high‐resolution stereolithography devices are based on Digital Light Processing (DLP) and thus sacrifice lateral printing size for resolution. Consequently, even 10 years after the advent of microstereolithography there is no commercialized 3D printing system that can effectively fulfill all the demands to replace soft lithography for microfluidic prototyping. In this work, for the first time, This study demonstrates that a commercial laser‐based stereolithography device is capable of manufacturing microfluidic chips with embedded channels smaller than 100 µm with a footprint of 7.24 × 0.3 cm2. A chip fabricated in poly(ethylene glycol) diacrylate (PEGDA) that can readily be used for fluid mixing, is presented in this study. This research shows that the accessibility of high‐resolution chips with footprints of several cm2, using laser‐based stereolithography, enables the manufacturing of truly microfluidic systems with high impact on prototyping and manufacturing.

Thermal and manufacturing properties of hollow-core 3D-printed elements for lightweight facades

High-performance facades play an important role in achieving Net-Zero goals by 2050. As a facade manufacturing technology, 3D printing offers the opportunity to create site-specific and high-performance building envelopes. In this manuscript, the thermal performance of components fabricated with different Material Extrusion methods is studied experimentally, and the fabrication time is calculated, thereby examining both performance and fabrication viability. More specifically, this manuscript investigates the thermal performance of 3D-printed facades using Hollow-Core 3D printing (HC3DP) and explores the potential of this novel approach in creating thermally insulating, lightweight, and translucent building envelopes. The research compares the thermal resistance of HC3DP specimens to conventional material extrusion methods, such as desktop 3D printers, and granular-based, large-scale pellet extrusion. Different methods are used to determine the thermal resistance of specimens, including the dynamic thermal conductivity measurement for the desktop 3D-printed (3DP) specimens, and the steady-state hot box heat flux meter approach for HC3DP. The results demonstrate that HC3DP enables lower Thermal transmittance (U-value)s at lighter weight and faster printing speed, making it a promising avenue for further research. Additionally, the combination of HC3DP with aerogel is shown to create ultra-lightweight and thermally insulating 3D-printed facade elements. The potential of this new facade technology is also highlighted in comparison with established facade systems. All in all, the manuscript provides insights into the thermal performance of 3D-printed facades at different printing resolutions and emphasizes the importance of printing time and material consumption in determining the most promising 3D printing approach for lightweight and thermally insulating facades.

Influence of printing time reduction on dimensional accuracy of final build FDM parts by modifying the G-code program

Influence of printing time reduction on dimensional accuracy of final build FDM parts by modifying the G-code program

Model performance evaluation of build time using geometric shape complexity and process parameters in material extrusion

Additive Manufacturing (AM) is gaining widespread interest and recognition in both academia and industry due to its numerous advantages over traditional manufacturing processes. The AM process offers two significant benefits: mass customization and the ability to achieve higher shape complexity at no cost. The present study introduces a methodology for quantifying the shape complexity of feature-based parametric models that AM can produce. This method is exclusively a quantitative approach based on the “number of inputs” required to define the feature or integral sketch. Furthermore, an Artificial Neural Network (ANN) based predictive model for estimating the AM build time has been developed and validated. Supervised Machine Learning (ML) is employed to predict printing time by considering significant design and manufacturing parameters that affect the overall process time. A performance evaluation is conducted between the developed ANN model and a statistical Multiple Linear Regression (MLR) model. The validation Computer Aided Design (CAD) samples are chosen to evaluate the ANN and MLR model's performance to predict the build time. It is observed that the ANN model outperforms the MLR model in estimating the build time of complex geometries. Regarding the efficiency of models, the ANN model achieved an R square value of 0.880 and a lower prediction error of 15.543 %. However, the MLR model showed some sensitivity to high complexity and large volume parts when predicting printing time, with a R square value of 0.96. In contrast, the ANN model is more precise in forecasting FDM build time for complex geometries and large volume parts.

Research on a Support-Free Five-Degree-of-Freedom Additive Manufacturing Method.

When using traditional 3D printing equipment to manufacture overhang models, it is often necessary to generate support structures to assist in the printing of parts. The post-processing operation of removing the support structures after printing is time-consuming and wastes material. In order to solve the above problems, a support-free five-degree-of-freedom additive manufacturing (SFAM) method is proposed. Through the homogeneous coordinate transformation matrix, the forward and inverse kinematics equations of the five-degree-of-freedom additive manufacturing device (FAMD) are established, and the joint variables of each axis are solved to realize the five-axis linkage of the additive manufacturing (AM) device. In this research work, initially, the layered curve is obtained through the structural lines of the overhang model, and a continuous path planning of the infill area is performed on it, and further, the part printing experiments are conducted on the FAMD. Compared with the traditional three-axis additive manufacturing (TTAM) method, the SFAM method shortens the printing time by 23.58% and saves printing materials by 33.06%. The experimental results show that the SFAM method realizes the support-free printing of overhang models, which not only improves the accuracy of the parts but also the manufacturing efficiency of the parts.

Research on Additive Manufacturing Path Planning of a Six-Degree-of-Freedom Manipulator

The research on additive manufacturing (AM) path planning mainly focuses on the traditional three-axis AM path planning and five-degree-of-freedom (DOF) AM path planning, while there is less research on six-DOF AM path planning. In the traditional AM path planning algorithm, the filling path is discontinuous and there is long straight-line printing in a certain direction, which can easily lead to warpage deformation. Therefore, in this work, the six-DOF manipulator is taken as the main object to build an AM platform, and the mechanism of AM path planning of the manipulator is studied. The path planning algorithm combining the contour offset filling method and Hilbert curve filling is optimized by using a cubic uniform B-spline curve, and an AM path planning algorithm suitable for a six-DOF manipulator is obtained. A continuous printing path can be generated by this algorithm. It reduces the existence of long straight-line printing in a certain direction, thereby reducing the warpage deformation of the model and improving the molding quality of the model. The traditional three-axis AM device and the six-DOF AM platform were used to print two kinds of models. By comparing the printing time, the six-DOF AM platform was 43.70% and 37.94% shorter than the traditional three-axis AM device. The same model was printed on a six-DOF AM platform by using the parallel scanning filling method, the path planning algorithm combining contour offset and Hilbert curve, and the method proposed in this paper. Through experimental verification, the average warpage deformation of the model printed by the method proposed in this paper was reduced by 37.81% and 13.79%, respectively, compared with the other two methods.

Response of PLA material to 3D printing speeds: A comprehensive examination on mechanical properties and production quality

This study investigates the impact of printing speed on the mechanical properties of parts produced through the fused deposition modeling (FDM) method using a three-dimensional (3D) printer. Tensile test specimens, fabricated with Polylactic Acid (PLA) material on an Ender 3 S1 3D printer, were subjected to varying printing speeds from 15 mm/s to 105 mm/s in 15 mm/s increments, maintaining a 100% infill rate. Detailed measurements of sample masses, hardness values, and surface roughness were conducted to assess the potential effects of printing speed on PLA’s mechanical properties. Porosity values were also calculated to evaluate internal structure homogeneity and void ratios. The results indicate that an increase in printing speed leads to a substantial reduction in production time. For instance, at a speed of 15 mm/s, the printing time was 119 minutes, decreasing to 15 minutes at 105 mm/s. As speed increased, there was a tendency for a decrease in sample masses, with a notable 12% reduction from 8.21 grams at 15 mm/s to 7.21 grams at 105 mm/s. While lower speeds (15 and 30 mm/s) exhibited higher Shore D hardness values, an overall decrease in hardness was observed with increasing speed. Surface roughness showed a proportional increase with printing speed; for example, at 0° angle, the roughness value increased from 0.8 at 15 mm/s to 1.9 at 105 mm/s. Moreover, tensile strength values decreased with higher printing speeds. For samples printed at 15 mm/s, the tensile strength was 60 MPa, decreasing to 44 MPa at 105 mm/s, representing a 27% reduction. These numerical findings underscore the significant influence of 3D printing speed on both production efficiency and the mechanical properties of the printed material.

Analysis of printing time components and powder utilisation efficiency of metal selective laser melting process in case of 316L and Ti6Al4V materials

ABSTRACT In selective laser melting technology, the productivity and the efficiency of powder utilisation were examined. Individual components of the printing time were determined by developing a specially designed model. Two main components of the powder recoating and the laser exposure time were given as a function of the filling ratio of the cross-section. Based on the results, the spreading time can increase the printing time by several hours, depending on the filling factor of the cross-section. In the case of a sampling of 70 prints, the individual elements and process of the powder usage were determined, as well as the mass measurement of the different amounts of powder in the case of 316L and Ti6Al4V materials. It turned out that 45–80% of the powder amount is not used to build the model, which is an essential for both printer users and equipment developers for material cost prediction.

Optimizing FDM 3D Printing of Medical Models

Present paper presents the results on four cases of optimization of FDM 3D printing of medical models used for training on specific medical issues (2 cases) and of personalized patient-specific models used for complex Trauma and Orthopedic surgical procedures planning (2 cases). Depending on optimization criteria (proper combination of model splitting – minimum need of supports/or no supports – minimization of printing time and material consumption, facile support removal and good surface quality), the modification of the Cura slicer recommended settings related to layer thickness and support pattern, support Z distance, support X/Y distance, support overhang angle, and minimum support area, allowed the reduction of 3D printing time with 24% and 33%, very easy support removal, and an assessment of surface accuracy and quality as very good for the purpose, made by end users.

Machine Design and Development of CoreXY FDM 3D Printer for Learning

This research aims to design and develop CoreXY FDM 3D Printer that can be optimized for learning purposes. By detailing aspects of design, hardware, and software, this research is expected to make a significant contribution in improving the quality of learning. Research using the Research and Development method, carried out based on the Machine Learning System Development model with stages in the form of Problem Understanding, Data Handling, Model Building, and Model Monitoring. The results showed that the lowest average depreciation value in the 3D printer developed was smaller than the 3D Printer machine from the previous study. The best print quality was produced in experiment number 3 where the print results were almost flat and smooth. So that the best print parameters are produced at a layer thickness of 0.1 mm and a print speed of 60 mm / minute. Blackbox Test results show that all components of the 3D printer machine have been able to function properly. The results of the user trial questionnaire showed that the average value of all aspects received a value of 3.55 from a range of values 1-4, indicating that this machine is very good to be used as a medium in the learning process. Comparison of FDM CoreXY 3D Print printing process time after development shows shorter print time than FDM CoreXY 3D Printer machine before development.

Effect of infill pattern on the mechanical properties of PLA and ABS specimens prepared by FDM 3D printing

Fused deposition modelling (FDM) is a three-dimensional printing technique which has become more popular and spreading in many fields. In this process, the molten thermoplastic is deposited layer by layer using a heated nozzle. Users can set the infill pattern to save the material and printing time. The main objective of this study is to investigate the tensile properties of polylactic acid (PLA) and Acrylonitrile butadiene styrene (ABS) tensile specimens with different infill patterns such as lines, tri-hexagonal and lightning. Further, the test specimens were prepared as per ASTM D638 using Ender 3D printer with varying infill patterns. The specimens were subjected to tensile tests in a mechanical tensile testing machine. It was observed that the specimens with linear infill patterns obtained higher tensile strength than the tri-hexagonal and lightning pattern infilled specimens. Later on, a microstructural study was examined on the fractured surface using scanning-electron-microscopy (SEM). It shows that the line pattern specimens have more uniform structure when compared to hexagonal and lightning pattern specimens.

Enhancing 3D-Printed PP-CF parts: A novel resin-filling technique for mechanical property optimization

This study investigates a novel post-processing technique aimed at enhancing the mechanical properties of 3D-printed polypropylene-carbon fiber (PP-CF) composite parts. The method involves printing components with internal voids to reduce weight and printing time, subsequently filling these voids with a low-cost resin known for its superior mechanical properties. Through systematic experimentation varying infill density and pattern, key quantitative findings were obtained. Tensile strength generally increased with higher infill density, reaching a maximum of 55.664 MPa for the resin-filled triangle infill pattern with 60% infill density. Impact energy showed a decreasing trend with increasing infill density, with the highest impact energy of 0.5 J recorded for the resin-filled triangle infill pattern with 60% infill density. Microstructural analysis revealed that the triangle infill pattern at 60% infill density exhibited the most effective resin penetration, contributing to superior mechanical performance. These findings emphasize the importance of infill pattern selection in resin distribution and mechanical enhancement in 3D-printed composite materials.

DESIGN AND FABRICATION OF CIVIL 3D PRINTER

The advent of 3D printing technology has revolution- ized the construction industry, offering innovative so- lutions for rapid, cost-effective, and sustainable build- ing practices. This research paper presents a compre- hensive study on the manufacturing and fabrication of a 3D concrete printer tailored for large-scale construc- tion applications. The paper outlines the design princi- ples, mechanical and electrical systems, material con- siderations, and software integration necessary for the development of an efficient and reliable 3D concrete printer. Key components of the printer, including the frame, extrusion system, and control mechanisms, are meticulously designed to ensure precision, stability, and durability. Advanced materials such as high- performance concrete mixes are formulated to meet the unique requirements of 3D printing, balancing workability, strength, and setting time. The integration of sensors and automation technology facilitates real- time monitoring and control, enhancing the accuracy and consistency of the printed structures. The implementation phase involved extensive testing and validation, highlighting the printer’s capability to construct complex geometries and large-scale ele- ments with minimal human intervention. Results indi- cate significant improvements in construction speed, cost savings, and material efficiency compared to tra- ditional methods. The paper concludes with a discus- sion on potential applications, challenges, and future directions for 3D concrete printing technology in the construction industry.

Innovative 3D printing of mechanoluminescent composites: Vat photopolymerization meets machine learning

Mechanoluminescent (ML) materials, which refers to a class of material that emits light upon being subjected to external mechanical stimuli, have been drawing attention due to their unique multifunctionality and potential applications in next-generation structural health monitoring. However, the practical use of ML materials has been limited by the lack of a universally acceptable framework for producing high-intensity ML composites and the challenges in fabricating complex 3D shapes. As a breakthrough, this paper presents a novel approach for producing SrAl2O4:Eu2+, Dy3+ particle-based ML composites using Vat photopolymerization (VP)–based 3D printing, and its process optimization via machine learning-based algorithm. In this study, multi-objective Bayesian optimization (MBO) with Gaussian process regression (GPR) as surrogate model is adopted to fine-tune three critical process parameters in VP process: ML particle content, layer thickness, and cure ratio, aiming for both strong ML properties and reduced printing time. GPR models the complex process input-output relationship, utilizing data collected from experiments. The Pareto-optimal solutions identified by MBO not only enabled the rapid production of high-performance ML specimens but also provided empirical insights into how process parameters affect the end product’s ML property and overall printing time. Furthermore, a micromechanical method for analyzing ML particle volume fraction dependence of the ML intensity is presented to analyze the result. Finally, the practical applicability of the proposed framework was validated by testing ML-based stress sensors and mechanical components using the optimized VP process.

Densification and rheological behaviors of 8YSZ powders for Vat photopolymerization-based additive manufacturing

Vat photopolymerization additive manufacturing technology allows the shaping of ceramic structures with limitless opportunities in terms of design freedom, structural resolution, and improving processing speed while reducing cost and wastage. The quality of a final product is influenced by the raw materials and processing routes. The particle size distribution of ceramic powders significantly affects ceramic slurry's rheology and cure behaviour as well as the densification process during sintering. This work studies the rheological properties of slurries prepared from 8 mol.% yttria-stabilized zirconia powders with various particle size distributions and densification of green bodies prepared from these suspensions. The suspension with a narrow particle size distribution showed a non-Newtonian behavior with a viscosity of >1 Pa s at a solid loading above 29 vol%, and a significant densification at a sintering temperature of 1400 °C. The viscosity of a suspension prepared from a powder with a wide particle size distribution was <1 Pa s in a solid loading range of 29–37 vol%. The higher cure depth at a lower exposure energy for slurry with coarse particles allowed a reduction of the printing time, while suspension with fine particles can be used for high-resolution printing with longer exposure time.

Magnetically Actuated GelMA‐Based Scaffolds as a Strategy to Generate Complex Bioprinted Tissues

AbstractThe 3D bioprinting of complex structures has attracted particular attention in recent years and has been explored in several fields, including dentistry, pharmaceutical technology, medical devices, and tissue/organ engineering. However, it still possesses major challenges, such as decreased cell viability due to the prolongation of the printing time, along with difficulties in preserving the print shape. The 4D bioprinting approach, which is based on controlled shape transformation upon stimulation after 3D bioprinting, is a promising innovative method to overcome these difficulties. Herein, the generation of skeletal muscle tissue‐like complex structures is demonstrated by 3D bioprinting of GelMA‐based C2C12 mouse myoblast‐laden bio‐ink on a polymeric magnetic actuator that enables on‐demand shape transformation (i.e., rolling motion) under a magnetic field. Bioprinted scaffolds are used in both unrolled (open as control) and rolled forms. The results indicate that C2C12s remain viable upon controlled shape transformation, and functional myotube formation is initiated by the 7th day within bioprinted platforms. Moreover, when the rolled and open groups are compared regarding MyoD1 staining intensity, the rolled one enhanced MyoD1 expression. These results provide a promising methodology for generating complex structures with a simple magnetic actuation procedure for the bioprinting of tissue‐engineered constructs with enhanced cell viability and functionality.

Enhancing interlayer bonding strength of 3D printed ternary geopolymer using calcium carbonate whiskers spray

Weak interlayer bonding, especially induced by a long period of printing interruption, is one of the major concerns for 3D printing concrete. The effect of CaCO3 whiskers suspension (CWS) spray and printing time interval on the interlayer bonding of 3D printing fly ash-granulated blast furnace slag-steel slag based geopolymer was investigated with splitting tensile strength and direct shear strength tests. The underlying mechanisms were explored based on the characterization of micromorphology, porosity, surface roughness and reaction kinetics of interlayer area. It was revealed that the CWS spray at appropriate concentrations can significantly improve the interlayer bonding of geopolymer printed at extended printing intervals, with 0.05 g/mL of CWS increasing the shear strength up to 71% at 60 min and 0.10 g/mL of CWS increasing the splitting tensile strength by 40% at 40 min. The CWS at proper concentrations could replenish the interlayer moisture, fill the interlayer voids and provide nucleation sites for geopolymerization and hydration products, i.e., N(C)-A-S-H and C-S-H gels. However, excessive CaCO3 whiskers or water content was harmful to the interlayer bonding. As the reaction process and microstructure of 3D printed ternary geopolymer were synergistically impacted by the printing time interval, residual water content, compensated moisture and CaCO3 whisker reinforcement, the mix of CWS spray should be carefully designed to optimize its effectiveness on the interlayer strengthening.