Printing Angles Research Articles

Construction and Validation of Simulation Models of Samples Made from 316L Steel by Applying Additive Technique.

The main aim of the study includes research concerning the strength of samples printed out of 316L steel in the form of laminates and the creation of reflective simulation models with regard to the results obtained during the research. In addition, the tests addressed the effect of the arrangement of the printed layers on the final strength of the object. Static tensile tests allowed the material constants of 316L steel in the form of dimensionally printed laminate to be determined. Tests were conducted on samples with different printed angles. The tests also covered the impact of the printing envelope on samples with the printing angles. Based on the determined material constants, simulation models for calculations using the finite element method were created. Furthermore, the study includes analytical and simulation calculations of plain laminate in order to verify the accuracy of the Composite Layup module in Abaqus CAE software. The study was summarized by compiling and commenting on the results obtained from the conducted research. Tests showed that there is a possibility of simulating the strength of the printouts from 316L steel using the FEM calculations. It was shown that the FEM model results are similar to those obtained in the tests. The calculated errors were from 3.6 to 14.4%. The linear model describes well the first part of the stress–strain curve, but in further research, it is strongly recommended that a proper and checked nonlinear anisotropic one is presented.

Comparison of Wear of Interim Crowns in Accordance with the Build Angle of Digital Light Processing 3D Printing: A Preliminary In Vivo Study.

The aim of this study is to evaluate the wear volume of interim crowns fabricated using digital light processing 3D printing according to the printing angle. A total of five patients undergoing the placement of a single crown on the mandibular molar were included. Interim crowns were fabricated directly in the oral cavity using the conventional method. A digital light processing 3D printer was then used to fabricate crowns with build angles of 0, 45, and 90 degrees. Therefore, four fabricated interim crowns were randomly delivered to the patients, and each was used for one week. Before and after use, the intaglio surfaces of the interim crowns were scanned using a 3D scanner. The volume changes before and after use were measured, and changes in the height of the occlusal surface were evaluated using the root mean square value. Data normality was verified by statistical analysis, and the wear volume in each group was evaluated using a one-way analysis of variance and Tukey’s honestly significant difference test (α = 0.05). Compared with the RMS values of the conventional method (11.88 ± 2.69 µm) and the 3D-printing method at 0 degrees (12.14 ± 2.38 µm), the RMS values were significantly high at 90 degrees (16.46 ± 2.39 µm) (p < 0.05). Likewise, there was a significant difference in the change in volume between the groups (p = 0.002), with a significantly higher volume change value at 90 degrees (1.74 ± 0.41 mm3) than in the conventional method (0.70 ± 0.15 mm3) (p < 0.05). A printing angle of 90 degrees is not recommended when interim crowns are fabricated using digital light processing 3D printing.

On the Mechanical Performance of Polylactic Material Reinforced by Ceramic in Fused Filament Fabrication.

This study addresses the potential of using ceramics-based filaments as a feedstock material in an additive manufacturing process. Tensile specimens of PLA-ceramic (PLC) material are manufactured using a fused deposition modelling process, applying various printing parameters including printing angle and part orientation. Mechanical testing is performed on both the filaments and 3D-printed parts, and the related engineering quantities are derived. The experimental results show that PLC wire properties are substantially restored for the horizontal and lateral printing orientations, with only a 9% reduction in stiffness. In addition, a typical elastic-plastic response is achieved with these orientations, allowing the PLC to achieve excellent stiffness and elongation-at-break performance. The mechanical performance of the PLC is explained by the large proportion of continuous filaments along the loading direction. In addition, the printing angle is found to be a secondary factor allowing for layups at −45°/+45° and 0°/90°, resulting in the best tensile performance. The downside of using PLC is the lack of mechanical transfer, which is associated with weak interfacial behaviour and the inability to achieve high tensile strength.

An Investigation on the Hardness of Polylactic Acid Parts Fabricated via Fused Deposition Modeling.

This paper investigated the hardness property of the fused deposition modeling (FDM)-printed PLA samples via different process parameters of printing and raster angles. The hardness data were sampled from the flat and edge surfaces of the samples. In addition, the effect of hardness characters after the ultraviolet (UV) curing process was analyzed. Furthermore, this research found that the printing and raster angles significantly affected the hardness value of the PLA part, which slightly increased after the UV irradiation. Moreover, the results of this study will provide a reference for the field of FDM application.

Effect of post-processing conditions on polyacrylate materials used in stereolithography

Additive manufacturing offers simple and cost-effective production of highly customizable 3D-components. One particularly interesting technology is stereolithography (SLA), which enables the fabrication of micro- and milliscale reactionware using transparent materials. In this work, the influence of 3D-printing settings such as printing angle and layer thickness and post-processing conditions, as well as the size and shape of the test samples, on the mechanical, thermal and physico-chemical properties is determined. Two photocurable acrylate resins were used for 3D-printing: Clear and High Temperature. Post-curing of the test samples was performed using several methods and varying treatment times. The tensile test results show that a higher degree of cure results in a higher tensile strength and smaller elongation. On the other hand, layer thickness and print angle have a stronger influence on the tensile strength than some of the post-curing methods. In particular, the samples printed at 45° angle with the smallest layer thickness of 25 µm were found to be the toughest. When comparing Clear and High Temperature material, it is found that the Clear samples can withstand higher stress and strain, but the samples made of High Temperature resin are more rigid and show higher Young's modulus. Differential scanning calorimerty (DSC) tests show that post-curing reduces curing enthalpy, while the glass transition temperature shifts to higher temperatures, indicating crosslinking of the polymer chains. The swelling test showed that both resins can be considered water resistant with an absorption of less than 2% within 24 h. Regarding ethanol and acetone, High Temperature resin proved to be more resistant compared to the Clear resin. The samples post-cured in the SunTest chamber also showed much lower absorption of ethanol and acetone. The contact angle measurement shows that all samples are hydrophilic, regardless of the degree of post-curing or the printing angle.

Investigation of the dynamic mechanical analysis and mechanical response of 3D printed nylon carbon fiber composites with different build orientation

AbstractThe effect of printing angle on the mechanical behavior of 3D printed carbon fiber reinforced nylon composites is investigated. Three types of print angles, namely angular, vertical and horizontal, are considered in the present study. Dynamic mechanical analysis, and flexural and tensile tests are performed to evaluate the mechanical behavior of specimens. The dynamic mechanical analysis test reveals higher storage and loss modulus in horizontal specimens as compared with angular and vertical specimens, mainly credited with better mechanical restraints imposed by carbon fibers on the matrix movement. Higher damping capability was also noted with horizontal specimens. Flexural properties of horizontally printed specimens are better as compared with the other configurations attributed to good stress transferability between the constituents. Tensile specimens also depict higher modulus and strength for horizontally printed specimens owing to higher resistance offered by the carbon fibers to tensile loading and good compatibility of constituents. Finally, the structure–property relationships are understood by analyzing the specimens under a high‐resolution scanning microscope.

Hybrid Additive Manufacturing of Fused Filament Fabrication and Ultrasonic Consolidation.

Fused filament fabrication (FFF) additive manufacturing technology has the advantages of being low cost, having a simple operation, using wide types of molding materials, and producing less pollution during the printing process. However, the mechanical properties of the molded sample are unsatisfactory due to the limited bonding force between the filaments during the forming process, which limits its further development and application in the engineering field. Herein, the hybrid additive manufacturing technology for heterogeneous materials based on the ultrasonic-assisted enhanced fused filament fabrication technology was proposed. The mechanism of ultrasonic vibration on the strengthening of FFF samples was explored. The influence mechanisms of bonding time and ultrasonic strengthening times, ultrasonic strengthening and static load compression on the strengthening of mechanical properties of the sample were investigated. The effects of the thickness and printing angle of the FFF samples on the ultrasonic-enhanced mechanical properties were explored. The tensile strength of the one-time ultrasonic-strengthened sample is up to 43.43 MPa, which is 16.12% higher than that of the original. The maximum bending strength of the four-time ultrasonic-strengthened sample is 73.38 MPa, which is 78.98% higher than that of the original. Ultrasonic strengthening not only re-fused the pores inside the sample, but also improved the bond strength between the rasters. With the increase in the thickness of the sample, the increase rate of ultrasonic to the strength of the sample decreased significantly. The effects of ultrasound on the interlayer adhesion of samples with various printing angles were different. Based on the systematic research on the influence mechanism of ultrasonic process parameters and molding process parameters on the strengthening of FFF, a molding method for additively manufacturing heterogeneous material parts while strengthening the mechanical properties of FFF samples was proposed, and the influence mechanisms of the molding process on the mechanical properties and shape memory properties of the sample were explored, which can broaden the application of FFF technology in the engineering field.

Influence of printing direction on the dynamic response of additively-manufactured polymeric materials and lattices

Additive manufacturing techniques facilitate fabrication of polymeric lattice structures comprising complex cell architectures, via the ability to fabricate component struts at specified angles. However, the inherent layer-wise fabrication process, especially for Fused Deposition Modelling (FDM), introduces angle-dependent properties depending on the orientation with respect to the printing bed. This results in lattices displaying different mechanical responses, depending on the direction of loading. The present study examines how the static and dynamic tensile material properties of cell strut material are influenced by the angle of printing. Specimens printed at various angles were subjected to quasi-static tensile loading, as well as dynamic extension using a tensile split Hopkinson bar device. It was found that the degree of rate-sensitivity depends on the printing angle. Octet and Hybrid Structure (HS) lattices were also fabricated and subjected to quasi-static and impact compression along the printing direction and transverse to it. The results show that the load-deformation responses and lattice crushing patterns differ significantly. Finite element models, incorporating both printing angle and rate dependent strut material and failure properties, were established, to analyse the deformation with respect to loading direction, at both lattice sample and cell-component levels.

Mathematical modelling of flow field in 3-dimensional additive printing

The distribution of flow field caused by squeegee movement exercises a crucial influence over the transfer of aqueous polyurethane dispersion (PUD) in the 3-dimensional (3D) additive printing for warp knitted vamp. So, the current study's goal is to develop a mathematical model for flow field related to printing parameters, where analytical solution of squeegee deformation is crucial. This paper presents an analytical procedure to deduce the deformation equation of wedge squeegee with variable section based on the semi-inverse method from elastic mechanic. Then a mathematical model of 3D additive printing is obtained using lubrication theory, leading to non-dimensional velocity as well as the integral expression of hydrodynamic pressure that is solved by the Romberg integration algorithm. Further analysis reveals the similarities and differences between flow field studied in this paper and Couette flow. More importantly, the hydrodynamic pressure near the squeegee tip plays a crucial role in PUD transfer. Then, the sensitivity analysis is carried out to quantify the impacts of process parameters on hydrodynamic pressure. Among printing parameters, the printing angle has the greatest influence on hydrodynamic pressure, which is often neglected in traditional engineering studies. The theoretical calculations are compared against the simulations of finite volume method, showing good agreement for the distribution of velocity and pressure. This work paves the way for adjustment of process parameters and mechanism study of PUD transfer.

Facile microfabrication of three dimensional-patterned micromixers using additive manufacturing technology

This study investigates the manufacturing method of oblique patterns in microchannels and the effect of these patterns on mixing performance in microchannels. To fabricate three-dimensional (3D) and oblique patterns in microchannels, 3D printing and replica methods were utilized to mold patterns and microchannels, respectively. The angle and size of the patterns were controlled by the printing angle and resolution, respectively. The mixing efficiency was experimentally characterized, and the mixing principle was analyzed using computational fluid dynamics simulation. The analysis showed that the mixing channel cast from the mold printed with a printing angle of 30° and resolution of 300 μm exhibited the best mixing efficiency with a segregation index of approximately 0.05 at a Reynolds number of 5.4. This was because, as the patterns inside the microchannel were more oblique, “split” and “recombine” behaviors between two fluids were enhanced owing to the geometrical effect. This study supports the use of the 3D printing method to create unique patterns inside microchannels and improve the mixing performance of two laminar flows for various applications such as point-of-care diagnostics, lab-on-a-chip, and chemical synthesis.

The digital printing of chromatic pattern with a single cellulose nanocrystal ink

Cellulose nanocrystals (CNCs), a type of natural photonic crystal, have been used to develop various optical materials owing to their chiral nematic organization, renewability, sustainability, and abundance. However, scaling up the production of CNC-based photonic materials remains challenging because of their long self-assembly time, inevitable assembly defects, static optical properties, and brittle nature. To address these drawbacks, the current study introduces flexible photonic hydrogels with chromatic patterns that are 3D printed using CNC-based inks. These viscoelastic inks were composed of photopolymerizable monomers and CNCs that harbored high aspect ratios. The luminance and color difference of the patterns in the photonic hydrogels were digitally controlled by varying the printing angles and the number of layers. Furthermore, our technique was validated by printing recognizable QR codes, Tai-chi, and hydrogel color cards. The current study provides a facile, fast, reproducible, accurate, and scalable strategy for fabricating photonic hydrogels from sustainable materials with chromatic patterns visible only in polarized light, thereby demonstrating their potential use in optical devices, anti-counterfeiting applications, and information concealment and dissemination.

Mechanical characterization of 3D printed samples under vibration: Effect of printing orientation and comparison with subtractive manufacturing

This paper describes dynamical characterization of mechanical structures manufactured by Selective Laser Melting (SLM) process at various orientations. The samples are also compared to subtractive component. The additive metal samples were manufactured by a 3D printer (Renishaw AM 250, Renishaw) and were tested using vibration analysis of embedded-free beam installation. Experimental setup was replicated using the same geometry of samples printed at various orientations and submitted to low velocity impact. Accelerometers allowed recording mechanical responses of all the specimens, allowing characterizing the dynamic behavior of each component and the effect of the printing orientation and printing angles.

Comparison of flexural strength of parts fabricated by vacuum casting with different fillers and fused deposition modeling with different printing angles

Comparison of flexural strength of parts fabricated by vacuum casting with different fillers and fused deposition modeling with different printing angles

Evaluation of wear behaviour of various occlusal splint materials and manufacturing processes

ObjectivesTo investigate the volumetric and vertical loss of occlusal splints manufactured by conventional (heat-cure), subtractive (CAD/CAM) and additive (3D-printing) methods. MethodsSix occlusal splint materials were investigated (n = 126), using three manufacturing methods: heat-cured, CAD/CAM and 3D-printed built-in three different printing angles (0°,45°and 90°). Block-on-ring wear testing was performed with extracted human molars as the antagonist. All samples were tested with an applied force of 49N at 1 Hz and 60RPM in artificial saliva at 37 °C for six and 12 months. Scanning electron microscopy images were analysed to evaluate the wear on the tooth enamel and in the splint material. Volumetric and vertical wear loss were statistically analysed. ResultsThe lowest volumetric and vertical loss was observed in CAD-CAM materials (6.44 ± 1.77 mm3 and 48.3 ± 7.14 μm) with no statistical significance to the heat-cured material (17.22 ± 9.23 mm3 and 148 ± 121.1 μm) after 12 months (p < 0.172). The mean volumetric loss of 3D printed materials ranged from 0.25 ± 0.15 mm3 to 0.29 ± 0.1 4mm3 with no statistical difference, whereas, the differences in vertical loss from 131.63 ± 44.1 μm to 493 ± 79.19 μm were statistically significant (p < 0.001). The highest vertical loss was observed in the KeySplint Soft 3D printed at 90° (385.35 ± 82.37 μm), whereas FreePrint Splint 2.0 with a build angle of 0° had the highest volumetric loss (204.59 ± 25.67 mm3). ConclusionCAD-CAM material had the highest wear resistance followed by heat-cured material.KeySplint Soft and FreePrint Splint 2.0 3D printed materials would be preferred for patients that do not have severe bruxing episodes. No significant wear of human enamel after six and 12 months was observed under SEM for any tested materials.

Fracture mechanics performance of 3D printed amorphous thermoplastic polymers at impact and quasi-static loading

Rapid manufacturing of individualized products made from plastics using 3D printing technologies will now become a highly growing market. However, the influence of morphology and processing parameters (such as speed of printing and screen angle) on the fracture mechanics performance of such additively produced materials is still inadequately investigated. Therefore, the effect of processing parameters, loading rate (impact and quasi-static loading) on the crack-growth behaviour (unstable and stable crack growth) of thermoplastic polymers (acrylonitrile–butadiene–styrene copolymer (ABS) and polycarbonate (PC)) has been analyzed using instrumented Charpy impact test, essential-work-of-fracture approach and crack-resistance-curve concept combined with non-destructive methods. Whereas the printing speed doesn't affect the fracture mechanics parameters the building orientation is clearly affecting the fracture performance. Here the orientation 45°/45° reveals higher toughness than the orientation 0°/90° due to mode II portions during the fracture process.

Optimization of Printing Parameters for Digital Light Processing 3D Printing of Hollow Microneedle Arrays.

3D printing is an emerging technology aiming towards personalized drug delivery, among many other applications. Microneedles (MN) are a viable method for transdermal drug delivery that is becoming more popular for delivery through the skin. However, there is a need for a faster fabrication process with potential for easily exploring different geometries of MNs. In the current study, a digital light processing (DLP) method of 3D printing for fabrication of hollow MN arrays using commercial UV curable resin was proposed. Print quality was optimised by assessing the effect of print angle on needle geometries. Mechanical testing of MN arrays was conducted using a texture analyser. Angled prints were found to produce prints with geometries closer to the CAD designs. Curing times were found to affect the mechanical strength of MNs, with arrays not breaking when subjected to 300 N of force but were bent. Overall, DLP process produced hollow MNs with good mechanical strength and depicts a viable, quick, and efficient method for the fabrication of hollow MN arrays.

Effect of print orientation on the dimensional accuracy of orthodontic aligners printed 3-dimensionally

Fabrication of orthodontic aligners directly via 3-dimensional (3D) printing presents the potential to increase the efficiency of aligner production relative to traditional workflows; however tunable aspects of the 3D-printing process might affect the dimensional fidelity of the fabricated appliances. This study aimed to investigate the effect of print orientation on the dimensional accuracy of orthodontic aligners printed directly with a 3D printer. A digitally designed aligner of 500μm thickness was printed in 3D in Grey V4 (Formlabs, Somerville, Mass) resin at 8 angulations at 45° intervals (n=10 per angulation) using a stereolithography 3D printer. Each aligner was scanned with an optical scanner, and all but the intaglio surface of each scan was digitally removed. Each resultant scan file was superimposed onto the isolated intaglio of the designed master aligner file. The dimensional deviation was quantified with Geomagic Control software (3D Systems, Rock Hill, SC), and data were analyzed using R statistical software (version 2018; R Core Team, Vienna, Austria) (P<0.05). Print angle showed a statistically significant effect on standard deviation, average positive deviation, absolute average negative deviation, and percentage of points out of bounds (tolerance bounds defined as ±250μm)(P<0.05). Qualitative analysis of the 3D surface deviation maps indicated that the 0° and 90° groups showed less deviation and appeared to be the most accurate in the anterior regions. Overall, the majority of the print angle groups studied were not printed within clinically acceptable tolerance ranges, with the major exception being the 90° group, which printed nominally within clinically acceptable tolerance ranges. With the workflow applied, print orientation significantly affects the dimensional accuracy of directly 3D-printed orthodontic aligners. Within the limitations of this study, printing at the 90° angulation would be advised as it is the group with the most accurate prints relative to the 7 other orientations investigated, although not all differences were statistically significant.

Effect of Printing Parameters on Mechanical Behaviour of PLA-Flax Printed Structures by Fused Deposition Modelling.

Few studies have reported the performance of Polylactic acid (PLA) flax feedstock composite for additive manufacturing. In this work, we report a set of experiments conducted by fused filament technology on PLA and PLA-flax with the aim of drawing a clear picture of the potential of PLA-flax as a feedstock material. Nozzle and bed temperatures are both combined with the printing angle to investigate their influence on structural and mechanical properties. The study shows a low sensitivity of PLA-flax to process parameters compared to PLA. A varied balance between shearing and uniaxial deformation is found consistent with tensile results where filament crossing at −45/+45° provides the optimal load-bearing capabilities. However, Scanning Electron Microscopy (SEM) and high-speed camera recording shows a limiting reinforcing effect of flax fibre due to the presence of intra-filament porosity and a significant amount of fibre pull-out resulting from the tensile loading. These results suggest that the quality of the bond between PLA matrix and flax fibre, intra-filament porosity, and surface roughness should receive more attention as well as the need for more continuous fibre reinforcement in PLA filaments to optimise the performance of PLA-flax printed materials.

Effect of Build Orientation on Mechanical Behaviour and Build Time of FDM 3D-Printed PLA Parts: An Experimental Investigation

One of the important process parameters affecting the tensile strength and build time of the part is the build orientation. Therefore, in this study, FDM 3D-printed PLA parts were fabricated at different build orientations to examine the effects of build orientation on the tensile properties and build time of material. In this regard, three build orientations and three print angles were examined. According to results, tensile strength decreased when the build orientation of the parts was aligned from flat to upright direction and 0° to 90° printing angle. For upright build orientation, 36% less tensile strength obtained than the flat ones because of the fracture mode and the loading direction. In terms of build time, build time increased as the build orientation changed from flat to upright. Therefore, the build orientation had a big impact on the tensile properties and build time of the parts produced using FDM. The findings of this study will contribute to the literature on proper build orientations and print angles.

Simulated and Experimental Investigation of the Mechanical Properties and Solubility of 3D-Printed Capsules for Self-Healing Cement Composites.

In the concrete industry, various R&D efforts have been devoted to self-healing technology, which can maintain the long-term performance of concrete structures, which is important in terms of sustainable development. Cracks in cement composites occur and propagate because of various internal and external factors, reducing the composite’s stability. Interest in “self-healing” materials that can repair cracks has led researchers to embed self-healing capsules in cement composites. Overcoming the limitations of polymer capsules produced by chemical manufacturing methods, three-dimensional (3D) printing can produce capsules quickly and accurately and offers advantages such as high material strength, low cost, and the ability to fabricate capsules with complex geometries. We performed structural analysis simulations, experimentally evaluated the mechanical properties and solubility of poly(lactic acid) (PLA) capsules, and examined the effect of the capsule wall thickness and printing direction on cement composites embedded with these capsules. Thicker capsules withstood larger bursting loads, and the capsule rupture characteristics varied with the printing angle. Thus, the capsule design parameters must be optimized for different environments. Although the embedded capsules slightly reduced the compressive strength of the cement composites, the benefit of the encapsulated self-healing agent is expected to overcome this disadvantage.