Printing Technology Research Articles

Minimizing Polymer Curl Distortion and Heat Impact to Improve Digital Light Processing Printing Accuracy via Subdivision Method

Curl distortion has been a persistent challenge for vat photopolymerization‐based printing technology such as digital light processing (DLP), leading to structural deformation and print failures. This study presents a new approach to mitigate curling distortion and heat effects during DLP printing by dividing the printing layer image into sequential subimages, using a breadth‐first search algorithm. The progressive curing process, resembling a ripple pattern, results in a significant improvement in printing accuracy. The deviation is reduced tenfold when the layer image is divided into subimages with 10 pixels for a 32 mm diameter disc. Additionally, subdivision strategy helps to reduce the heat effect during photopolymerization, as monitored in situ by a long‐wave infrared camera. The successful reduction of residual stress using the subdivision strategy results in a 75% improvement in the mechanical performance of the printed products. The simple adoption of subdivision strategy in practical 3D printing applications is also demonstrated. For solid 3D printing structures, introducing intervals within the solid printing layers—such as using a grid structure instead of a fully solid one, can help to reduce curling and heat effects, thereby improving 3D printing accuracy.

Viscosity measurements of selected lunar regolith simulants

Abstract In the context of evaluating lunar construction options, this study focuses on characterizing the viscosities and glass transition properties of lunar regolith simulants to support the development of additive manufacturing processes using molten regolith. Employing the modular TUBS lunar regolith simulant system, we measured the viscosities of different simulants through high-temperature experiments conducted between 1,051 °C and 1,490 °C using Concentric Cylinder viscometry in air. Additionally, Differential Scanning Calorimetry (DSC) was utilized to evaluate the glass transition temperatures, which were in the range between 689 °C and 815 °C. The measured viscosity data were parameterized by the Vogel—Fulcher—Tammann (VFT) equation, adept at describing the viscosities and related properties of silicate liquids. The measured viscosities were compared with the predicted values of six viscosity models. It was shown that the model by Sehlke and Whittington predicts the viscosities of the tested lunar regolith simulants at superliquidus temperatures best, whereby no model adequately predicts viscosities at the glass transition temperature, indicating a need for further research in this area. We infer that 3D printing technologies based on molten lunar regolith, are viscosity-wise best constrained to highland regions. The reduced environment on the Moon influences the 3D printing process in a positive manner.

Learning program enhances rehabilitation professionals’ perceived ease of using 3d printing: a pilot randomized controlled trial

The pilot study evaluated whether a learning program enhances a positive perception of 3D printing technology in rehabilitation professionals. Physical therapists, occupational therapists and speech-language-hearing therapists were recruited from a rehabilitation department in a middle-sized hospital. Participants were randomized to the control group (n = 13) or the intervention group (n = 14). An eight-week learning program consisted of a lecture on using a 3D printer and related software, a group discussion to integrate 3D printing into their clinical practices, and the implementation in their workplace. Outcome measures included the perception of 3D printing technology assessed by the Japanese version of the modified Technology Acceptance Model questionnaire for 3D printing technology (TAM-J). Assessment time points were pre-and post-intervention. As a result, all participants in the intervention group became capable of producing 3D-printed customized assistive devices. In the within-group analyses, the intervention group showed significant improvements in the TAM-J perception ease of use score (p = 0.012) with a large effect size (r = 0.75). Between-group analyses showed that the intervention group gained an additional improvement in the TAM-J perception ease of use score (p = 0.027) with a moderate effect size (r = 0. 43), indicating a significant improvement in the perceived ease of use of 3D printing technology in the intervention group. These observations suggest the 3D printing learning program could provide rehabilitation professionals with a positive perception of the technical aspect of 3D printing in their workplace.

High‐Precision Drop‐on‐Demand Printing of Charged Droplets on Nonplanar Surfaces with Machine Learning

Direct printing methods are widely recognized as efficient techniques for manufacturing printed electronics. However, several challenges arise when printing on nonplanar surfaces, especially using the drop‐on‐demand (DoD) approach. These challenges include ink flow due to gravity, precise ink deposition, and reproducibility. This study introduces an innovative method for highly accurate DoD material jetting on nonplanar 3D conductive surfaces, enabling precise production and trajectory control of charged droplets. The technique involves using a grounded 3D substrate as the target, where in‐flight droplets are subjected to an external electric field generated by gate electrode installed on a piezo activated droplet dispenser. Individual droplets are generated and controlled using a complex trigger system that relays variable‐voltage signals to the gate electrode. Moreover, a predictive model for droplet deposition, exhibiting an accuracy of 87%, is developed utilizing supervised machine learning (ML). This approach significantly improves the accuracy and repeatability of droplet deposition. Overall, this study presents an effective method of integrating piezoelectric and electrohydrodynamic printing technologies, complemented by ML. It addresses the challenges associated with printing on nonplanar surfaces using the DoD material jetting technique and shows considerable promise for enhancing efficiency, accuracy, and repeatability in the manufacturing of printed electronics.

Experimental study on buildability and mechanical properties of 3D printing cob

The application of 3D printing technology to earth buildings conforms to the development concept of low carbon, green and intelligent construction. The key issue lies in the development of earth material with both favorable buildability and sufficient mechanical properties. In this study, the printing parameters of mixture for 3D printing with different water contents were optimized. The optimum water content of 3D printing cob was determined based on the buildability. The result shows that when the flow spreading diameter is between 140 mm and 160 mm, 3D printing cob has good buildability performance. The optimum water content is 24.6 %. In addition, anisotropic performance was analyzed by compressive strength tests from three orthogonal directions. In particular, according to the test results of single printing limit height and yield stress, the buildability of 3D printing cob wall was analyzed. The building strategy of the printing divided into multiple times was obtained.

Printing Technology in Rural Society: Rethinking the Rise of Print Culture Through Chinese Genealogies, 1450–1644

This article re-examines the rise of print culture in early modern China by exploring the adoption of printing technology for publishing family genealogies. While genealogies had primarily been produced as manuscripts for centuries, in the mid-to-late Ming, elites in Southern China’s Huizhou prefecture began advocating for printed versions. This transition mirrored broader trends in Ming print culture, where printing technology was increasingly applied beyond traditional texts to a wide range of genres. Unlike scholars who have examined this shift from script to print as a precondition for other developments, I explore the process by which the print medium itself became desirable. By investigating the distinctive use of print in creating genealogies, this study underscores the diverse developmental paths of print culture in early modern China, illustrating the key role genealogies played in reshaping social relations within local communities.

Accuracy, Marginal, and Internal Fit of Additively Manufactured Provisional Restorations and Prostheses Printed at Different Orientations.

This systematic review aimed to assess the impact of printing orientation on the accuracy and properties of additively manufactured provisional restorations. A systematic literature search databases (PubMed, Scopus, Web of Science, and Cochrane) were conducted in July 2024 without language restrictions. The included studies were evaluated using the modified CONSORT checklist, and the effect measures and synthetic methods were employed to assess the accuracy of resin provisional restorations printed at various orientations. The web search resulted in 8228 records, and 15 records were ultimately included in the analysis. The printing orientation of provisional restorations has an impact on various factors such as the internal and marginal gap, trueness, precision, and accuracy. To achieve optimal results, it is recommended to utilize printing orientations of 180°, 150°, and 210°, as they showed lower marginal and internal gaps and higher accuracy. Caution should be exercised during the virtual positioning of supporting pillars, as this may also influence the overall accuracy. Horizontally and slightly tilted orientations have demonstrated superior accuracy. To achieve optimal results, factors such as printing layer thickness, printing technology, materials, and supportive pillars should be taken into consideration, besides the printing orientations. The selection of the optimum printing parameters overall printing orientations, layer thickness, and supportive pillar position can generate prosthetic and restorative dental parts with a long survival rate, saving time and effort by avoiding fracture, loss of retention, and consequent clinical complications.

Advancing optical transparency in 3D‐printed PLA parts using chemical post‐processing

AbstractFused filament fabrication (FFF) is an increasingly popular three‐dimensional (3D) printing technology known for its ability to produce complex 3D models at a low‐cost using polymer materials. Despite its advantages, the poor surface finish and high layer resolution in FFF‐printed parts have hindered its wider adoption, particularly for applications requiring high transparency. Thus, the current study investigates the transparency evaluation of chemically post‐processed 3D‐printed transparent polylactic acid (PLA) parts, focusing on enhancing optical transparency. Fused Filament Fabrication was employed to produce transparent parts made from PLA filament, which were subsequently treated at various time settings using various solvents, including tetrahydrofuran (THF), chloroform or trichloromethane (TCM), and ethyl acetate (EA). This study examines the impact of chemical post‐processing on the surface roughness, transparency, mechanical properties, and dimensional accuracy of solvent treated parts. It has been found that the THF solvent with 40 s of immersion time resulted in a maximum transmittance of 74.66% and minimum surface roughness of 1.777 μm. Based on this finding a case study was also conducted to apply the findings of the current investigation to a practical application. The findings highlight the potential of chemical‐based post‐processing techniques to improve the optical properties of 3D printed PLA, offering a promising approach for applications in optics, medical devices, and consumer goods requiring transparent components.Highlights Effect of chemical post‐processing on 3D‐printed PLA parts was investigated. Tetrahydrofuran, chloroform, and ethyl acetate were used as solvents. Surface roughness, transparency, hardness, and dimensional accuracy were analyzed. Reported a maximum transmittance of 74.66% and minimum surface roughness of 1.777 μm.

Evaluating the outcomes of three dimensional printing-assisted osteotomy on treating varus knee deformity from old tibial plateau fractures.

This study aimed to evaluate the outcomes of three-dimensional (3D) Printing-Assisted Osteotomy in treating varus knee deformity from old tibial plateau fractures. The study retrospectively analyzed patients with varus deformity induced by old-tibial plateau fractures between January 2019 and June 2023. All patients utilized 3D printed models for surgical planning. The Lysholm Knee Score (LKS), Visual Analog Scale (VAS) and Knee Society Score (KSS) were measured for functional outcomes. Medial Proximal Tibial Angle (MPTA), Joint Line Convergence Angle (JLCA), Mechanical Axis (%MA), Medial Tibial Plateau Depression (MTPD), and Femorotibial Angle (FTA) were measured for radiological outcomes. 15 patients (12 males and 3 females) were included in this study and followed up for 21.9 ± 8.6 (range, 12 to 28) months. Healing of the osteotomy sites were achieved in all patients at 15.8 ± 1.5 (range, 13 to 18) weeks. The knee varus deformities were significantly corrected as reflected by %MA (2.13 ± 13.1°(range, -20 to 22) versus 57.06 ± 9.8°(range, 41 to 70), p < 0.01), FTA (186.7 ± 3.2°(range, 181 to 193) versus 172.3 ± 2.1°(range, 169 to 175), p < 0.01), JLCA (5.8 ± 1.7°(range, 3 to 8) versus 1.3 ± 0.8°(range, 0 to 3), p < 0.01), and MPTA (5.6 ± 1.2°(range, 3 to 8) versus 1.2 ± 1.1°(range, -1 to 3), p < 0.01). Postoperative knee function showed dramatic improvements as reflected by VAS (4.6 ± 1.6 (range, 1 to 7) versus 0.7 ± 0.9 (range, 0 to 2), p < 0.01), KSS (50.1 ± 16.5 (range, 27 to 88) versus 88.5 ± 5.2 (range, 80 to 95), p < 0.01), and LKS (49.5 ± 10.2 (range, 37 to 69) versus 89.2 ± 2.5 (range, 87 to 94), p < 0.01). 3D printing technology provides a valuable tool for understanding deformities and optimizing osteotomy strategies, thereby improving surgical efficacy and treatment outcomes. Its clinical application is highly recommended.

Walnut shell/phenolic resin carbon electrodes via laser sintering and KOH activation

Currently, the application of 3D-printed biomass-based carbon electrodes is hindered by their suboptimal performance. This study utilizes walnut shell powder as a carbon source and employs Selective Laser Sintering (SLS) technology for the efficient 3D printing of a double-helix carbon precursor. High-performance biomass-based carbon electrodes are prepared through carbonization and KOH activation. Comparative studies on the microstructure and electrochemical performance of the carbonized and activated samples were conducted. Experimental results demonstrate that KOH activation significantly enhances the microstructure of the carbon electrodes, leading to marked improvements in their electrochemical performance. During desalination experiments, the carbon electrodes exhibited excellent ion removal efficiency, with a maximum conductivity reduction rate of 0.2 μS/cm·min, confirming their feasibility in seawater desalination applications. This research validates the potential of walnut shell biomass for the preparation of 3D-printed carbon electrodes, addressing bottlenecks in traditional carbon electrode manufacturing processes while promoting efficient biomass utilization and environmental protection.

Application of 3D printing in bacterial detection

Diseases caused by bacterial infections, especially pathogen variations and drug-resistant bacteria, are a serious threat to human health globally. Accurate and rapid identification of bacterial pathogens is essential for early diagnosis of infections and timely treatment of disease. At present, the routine diagnostic methods for identifying bacterial pathogens in clinic are bacterial culture, immunological detection, genetic analysis, etc. These methods occupy foundational position for bacterial detection that favors for clinical diagnosis of pathogen infection in daily life. Notably, 3D printing technology, together with 3D bioprinting technology, provides more options for bacterial detection due to its personalized design and manufacturing. Compared with traditional methods, 3D printing provides a more convenient, rapid and accurate bacterial detection platform, thus meeting the urgent needs of clinical and scientific research. Here, we have summarized the research progress and given a comprehensive review of 3D printing technology in bacterial detection, including bacterial detection sensors, microfluidic chips, bioprinting microarray technology, AI and spectroscopy technology, providing a scientific reference and filling in gaps in 3D printing-assistance bacterial detection. At the same time, technical advantages, challenges and future development trends will also be discussed in related healthcare fields.

Evaluating the Educational Impact of 3D-Printed Toys in Elementary Settings: A Mixed-Methods Study

This study explores the impact of integrating the use of disruptive technologies on 3D-printed toys within elementary education through a mixed-methods approach, combining an experimental design with qualitative interviews. Focusing on the potential of disruptive technologies to innovate educational practices, we divided participants into control and experimental groups, the latter engaging with the 3D-printed educational toys. Despite the innovative application of 3D printing technology in educational settings, our findings reveal no significant differences in the learning outcomes between the two groups. Therefore, this research contributes to the literature on educational innovation, suggesting that the mere introduction of novel technologies, such as 3D printing, may not be sufficient to enhance learning effectiveness. Regarding practical implications, the study is aimed at scholars, teachers, and educational managers, to underscore the necessity of a critical assessment of educational tools and calls for further investigation into how technology integrates into pedagogical frameworks to truly benefit elementary education. Received: 12 July 2024 / Accepted: 31 October 2024 / Published: 05 November 2024

The accuracy and efficiency of design and development of 3D printed integral anatomical acetabular prosthesis in total hip arthroplasty for Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip

Objective: To compare the accuracy and efficiency between the model development method and the software development method, which design and develop 3D printed integral anatomical acetabular prosthesis to be used in total hip arthroplasty(THA) for patients with Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip(DDH). Methods: Fifteen patients with end-stage hip osteoarthritis due to Crowe type Ⅱ and Ⅲ DDH who underwent THA in the Orthopedics Department of the First Affiliated Hospital of Bengbu Medical College between January 2015 and June 2023 were selected in this study retrospectively. There were 1 male (1 hip) and 14 females (17 hips) with a mean age of (55.1±9.1) years. There were 12 hips with Crowe type Ⅱ, 6 hips with Crowe type Ⅲ. The preoperative pelvis three-dimensional CT data in those patients were used to design integral anatomical acetabular prosthesis. The model development group used 3D printing technology to print life-size pelvis models. The acetabulum was reamed and the acetabulum cup was inserted into the socket according to conventional THA procedures. The bone defect above the acetabulum cup was filled with bone wax. The Mimics and 3-matic software were used to simulate the THA procedures, design and install the integrated anatomical acetabular prosthesis in the software development group. The operation time, the size of the acetabular cup, the volume and surface area of the acetabulum bone defect, the acetabular cup's inclination and anteversion, the horizontal distance and the vertical distance of hip rotation center were compared between the two methods. Results: The study in the two groups were all based on the data of 18 hips in the 15 patients. The horizontal and vertical distances of rotation center in the model development group and software development group was (32.08±1.80) mm, (32.17±2.40) mm and (14.36±1.53) mm, (15.11±1.45) mm, respectively (both P>0.05). The cup size in model development group was (48.56±1.15)mm, and it was (48.77±1.22) mm in the software group (P=0.160). The anteversion and inclination of the acetabular cup in the model and software groups were 23.79°±6.31°, 30.49°±11.03° and 15.17°±0.52°, 40.24°±0.58°, respectively (both P<0.01). The volume and surface area of the acetabulum bone defect in the model development group was (5.06±2.86) mm3 and (8.31±2.21) mm2, respectively, while it was (4.01±2.56)mm3 and (6.83±2.71) mm2, respectively, in the software development group (both P<0.05). The work time in the model development group was (24.43±0.68) h and (0.47±0.12) h in the software development group, respectively (P<0.001). Conclusion: Compared with the 3D printing model development method, the application of Mimics and 3-matic software to design and develop integrated anatomical acetabular prosthesis in total hip arthroplasty for Crowe type Ⅱ and Ⅲ DDH show advantages of convenience, high efficiency and more accuracy.

High Efficiency Producing Technology Applied in Metal Optical Lens by 3D Wax Printing Combined with Investment Casting

3D printing technology can easily and quickly produce small batch models and full-size parts, which has obvious and important benefits in shortening development time. Since metals exhibit excellent mechanical strength and high wear resistance, metal additive manufacturing (MAM) is a popular technology for making metal parts. However, metal powders and 3D-printing machines are costly, which increases the difficulty of achieving mass production through MAM. In this study, the 3D wax printing and investment casting (WPIC) approach was developed to manufacture high-quality metal optical lenses with high efficiency and low cost. The manufactured lenses had a diameter of 38.1 mm, two radii of curvature (15 and 90 mm), and a cooling channel. These lenses were manufactured through 3D printing by using wax patterns produced through investment casting. The manufacturing efficiency and machining accuracy of the lenses produced using the proposed method were compared with those of lenses produced through MAM and investment casting. The results indicated that the total costs of manufacturing an optical lens through MAM and investment casting were nine and eight times greater, respectively than that of manufacturing an optical lens through WPIC. In addition, the surface roughness of metal lenses manufactured through WPIC was 45% lower than that of lenses manufactured through MAM. Finally, the time required to manufacture 50 metal lenses was only 15 days when WPIC was used; the corresponding time was 25 days and 6 months when MAM and investment casting were used, respectively. According to the above-mentioned results, the WPIC process has excellent advantages in product manufacturing cost and developing schedule over MAM and traditional methods of investment casting.

Towards industry-ready additive manufacturing: AI-enabled closed-loop control for 3D melt electrowriting.

Melt electrowriting (MEW) is an emerging high-resolution 3D printing technology used in biomedical engineering, regenerative medicine, and soft robotics. Its transition from academia to industry faces challenges such as slow experimentation, low printing throughput, poor reproducibility, and user-dependent operation, largely due to the nonlinear and multiparametric nature of the MEW process. To address these challenges, we applied computer vision and machine learning to monitor and analyze the process in real-time through imaging of the MEW jet between the nozzle-collector gap. To collect data for training we developed an automated data collection methodology that eases the experimental time from days to hours. A feedforward neural network, working in concert with optimization methods and a feedback loop, is used to develop closed-loop control ensuring reproducibility of the printed parts. We demonstrate that machine learning allows streamlining the MEW operation via closed-loop control of the highly nonlinear 3D printing technology.

Effect of alkali metal sulfates on hydration properties of alpha-calcium sulfate hemihydrate for 3D printing

Three-dimensional printing (3DP) technology is an important means of achieving decorative convenience, personalization, and functional integration for future building construction. However, the setting time and hydration process of calcium sulfate hemihydrate (HH) present chanllenges for the 3DP application. This study aims to investigate the accelerating effect of alkali metal sulfates accelerators on the hydration transformation of HH into calcium sulfate dihydrate (DH). The setting time, conductivity, Ca2+ ion concentration, size distribution, and zeta (ζ) potential of gypsum slurries with different accelerators were measured. The results demonstrated that the accelerators significantly enhanced the hydration process of αlpha-calcium sulfate hemihydrate (α-HH). On the effect of accelerators, the setting times of gypsum slurries containing 30 wt% lithium sulfate (LS), sodium sulfate (NS) and potassium sulfate (KS) were accelerated by 82.56 %, 86.06 % and 97.13 %, respectively, compared to the control sample. The crystal particle sizes of hydration products decreased, and the absolute values of ζ potential increased to 1.85 mV, 3.1 mV, and 5.3 mV, respectively. The X-ray photoelectron spectroscopy (XPS) analysis revealed a shift in the peak values of the hardened specimens towards higher electric fields. This was accompanied by improved ion dispersion within the slurry, resulting in enhanced supersaturation of calcium sulfate dihydrate and crystallization of the crystal nuclei. Thus, the suitable accelerators can effectively achieve rapid solidification and hardening of high-fluidity gypsum slurries.

Application of 3D Printing Technology in Microreactor Fabrication

Application of 3D Printing Technology in Microreactor Fabrication

Comprehensive Study of Stereolithography and Digital Light Processing Printing of Zirconia Photosensitive Suspensions

Zirconia ceramics are used in a wide range of applications, including dental restorations, bioimplants, and fuel cells, due to their accessibility, biocompatibility, chemical resistance, and favorable mechanical properties. Following the development of 3D printing technologies, it is possible to rapidly print zirconia-based objects with high precision using stereolithography (SLA) and digital light processing (DLP) techniques. The advantages of these techniques include the ability to print multiple objects simultaneously on the printing platform. To align with the quality standards, it is necessary to focus on optimizing processing factors such as the viscosity of the suspension and particle size, as well as the prevention of particle agglomeration and sedimentation during printing, comprising the choice of a suitable debinding and sintering mode. The presented review provides a detailed overview of the recent trends in preparing routes for zirconium oxide bodies; from preparing the suspension through printing and sintering to characterizing mechanical properties. Additionally, the review offers insight into applications of zirconium-based ceramics.

Improving mechanical properties of 3D printed products through honeycomb structure and deep learning optimization

The use of three-dimensional (3D) Printing has rapidly grown due to its various applications in daily life. However, products made with this technology are not widely adopted because their quality is not yet seen as equal to that of products made with traditional materials. To address this issue, a honeycomb structure model was developed to improve the mechanical properties of the items created using 3D printing technology. This model not only saves materials, but also reduces printing time compared to previous models. The honeycomb structure was designed using a theoretical model, and its components were modified to ensure compatibility with the 3D printing extrusion method. Moreover, deep learning was used to optimise the honeycomb structure model’s boundary conditions by generating contour curves through linear interpolation. This process significantly improved the mechanical strength of the honeycomb structure model compared to structures made using 3D printing technology. The theoretical findings were validated through various material tensile tests conducted under different scenarios. As a result, this model can be used in various industries and products that use 3D printing technology, thanks to the critical role that deep learning in improving its mechanical properties.

Evaluation of the Accuracy of 3D Printed Patient-Specific Brain Biopsy Guide Using 3D Volume Rendering Technique in Canine Cadavers

The objective of this study was to evaluate the accuracy of a CT-based, 3D-printed, patient-specific brain biopsy guide (3D-psBBG) through the application of a transfrontal approach in canine cadavers. A total of ten canine cadavers, with weights ranging from 4.36 to 14.4 kg, were subjected to preoperative CT scans to generate 3D skull models. Customized biopsy guides were created based on these models and manufactured using 3D printing technology. Twenty spinal needle insertions were performed, and the accuracy of needle placement was evaluated through both CT and 3D volume-rendering techniques. The mean needle placement error was 2.1 mm, with no significant differences observed between insertions targeting the fronto-olfactory and piriform lobes. The 3D volume-rendering method demonstrated superior accuracy compared to the CT method, with statistically significant differences in placement errors for both targets. The average time required for the design and manufacture of the guides was 249 min. These findings indicate the high accuracy and potential clinical application of CT-based 3D-psBBG for improving diagnostic outcomes in veterinary neurology.