Printing Layer Thickness Research Articles

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.

Additive manufacturing of high-performance SiO2-Al2O3-K2O (Na2O) ceramic components via binder jetting technology

To resolve issues such as high sintering temperatures and relatively low relative densities and bending strengths of sintered bodies during the preparation of ceramic parts using binder jetting (BJ) additive manufacturing (AM) technology. In this study, high-performance SiO2-Al2O3-K2O (Na2O) ceramics were fabricated using quartz, kaolin, potassium feldspar, and sodium feldspar as raw materials through BJ technology. Initially, the sintering process of the BJ ceramics was studied by adjusting the ratio of potassium feldspar to sodium feldspar and the sintering temperature, which enhanced the relative density and bending strength of the silicate ceramics. Subsequently, using response surface methodology (RSM), the effects of print layer thickness (A), scraper speed (B), and ink volume per unit area (C) on the performance of the ceramics after sintering were investigated. Results indicated that the optimal parameters of the BJ printing process were determined using RSM: A was 250 μm, B was 3.44 mg cm−3, and C was 35 mm s−1. Under these conditions, the sintered ceramics achieved optimal relative densities, closed porosities, and flexural strengths of 89.05 %, 10.85 %, and 69.19 MPa for relative density, closed porosity, and flexural strength, respectively.

Optimization of Production Parameters for Impact Strength of 3D-Printed Carbon/Glass Fiber-Reinforced Nylon Composite in Critical ZX Printing Orientation.

Additive manufacturing (AM) methods are increasingly being adopted as an alternative for mass production. In particular, Fused Deposition Modeling (FDM) technology is leading the way in this field. However, the adhesion of the layers in products produced using FDM technology is an important issue. These products are particularly vulnerable to forces acting parallel to the layers and especially to impact strength. Most products used in the industry have complex geometries and thin walls. Therefore, solid infill is often required in production, and this production must take place in the ZX orientation. This study aims to optimize the impact strength against loads acting parallel to the layers (ZX orientation) of PA6, one of the most widely used materials in the industry. This orientation is critical in terms of mechanical properties, and the mechanical characteristics are significantly lower compared to other orientations. In this study, filaments containing pure PA6 with 15% short carbon fiber and 30% glass fiber were utilized. Additionally, the printing temperature, layer thickness and heat treatment duration were used as independent variables. An L9 orthogonal array was employed for experimental design and then each experiment was repeated three times to conduct impact strength tests. Characterization, Taguchi optimization, and factor analyses were performed, followed by fracture surface characterization by SEM. As a result, the highest impact strength was achieved with pure PA6 at 8.9 kJ/m2, followed by PA6 GF30 at 8.1 kJ/m2, and the lowest impact strength was obtained with PA6 CF15 at 6.258 kJ/m2. Compared to the literature and manufacturer datasheets, it was concluded that the impact strength values had significantly increased and the chosen experimental factors and their levels, particularly nozzle temperature, were effective.

Study of thermal stress deformation in hybrid 3D printing and milling process of PEEK material

Hybrid manufacturing can enable rapid production of personalized artificial bones that are made of Polyether-ether-ketone (PEEK) by integrating 3D printing and milling. A main challenge, however, is the thermal stress deformation that arises from the fused deposition process, leading to warping and shrinkage. As a result, the fabrication accuracy is significantly diminished. This work aims to address this challenge by investigating the thermal stress deformation behavior of PEEK in hybrid manufacturing. The main contributions of this work, therefore, include the development of a model for this thermal deformation behavior, and the identification of key parameters such as cross-section length ( Ls), printed layer thickness ( Lh), and current workpiece height ( He). Further, experiments are conducted based on response surface methodology (RSM) to explore the relationships between temperature variation rate (Δ T), end surface height difference (Δ S), and length shrinkage rate (Δ L) with critical hybrid processing parameters. Optimal parameter combinations are then identified. Our experiments demonstrate that the proposed methods effectively reduce the effects of warping and shrinkage.

Effect of Implant Analog Design and Additively Manufactured Casts' Printing Layer Thickness on the Linear and Angular Accuracy of Analogs for Direct Digital Workflow: An In Vitro Study.

To evaluate how implant analog design and printing layer thickness affect the linear and angular accuracy of implant analogs in additively manufactured casts, comparing with conventional implant analogs in stone casts. A reference cobalt chromium mandibular model with a single implant was digitized with an industrial optical scanner and scan bodies compatible with a pressure/friction fit (S) or a screw-retained (N) implant analog for direct digital workflow. These scans were used to fabricate casts with 50 μm (S-50 and N-50) and 100 μm (S-100 and N-100) layer thickness (n=10). Ten stone casts were made after single-step closed-tray polyvinylsiloxane impressions of the model (CNV). All casts were digitized with the same metal scan body and scanner used to digitize the master model, and these scans were superimposed over the scan of the master model to measure the linear (x, y, and z-axes) and angular (XY and YZ planes) deviations (Geomagic Control X). The precision of measured deviations was defined with the average deviation values. Generalized linear model analysis was used to compare the deviations within implant analogs for direct digital workflow, while 1-way analysis of variance and Dunnett's test were used to compare these analogs and conventional analogs (α = .05) Results. The analog design affected the linear deviations (y-axis), while the interaction between the analog design and the layer thickness, and the analog design affected the angular deviations (XY plane, P ≤ .030). S analogs had lower linear and angular deviations than N analogs, and S-50 led to lower angular deviations than N-50 (P ≤ .030). CNV led to higher linear accuracy (y-axis) than N-50, N-100, and S-100 and led to lower angular deviations than all test groups (XY plane) (P ≤ .025). The analogs in S-50 casts had positional trueness similar to or higher than those in other test groups and their accuracy was mostly similar to those in CNV casts. Implant analogs for direct digital workflow deviated more towards lingual and gingival, and conventional analogs deviated more towards buccal, occlusal, and distal. All analogs had a tendency to tilt towards lingual and distal.

The Effect of 3D Printing Layer Thickness and Post-Polymerization Time on the Flexural Strength and Hardness of Denture Base Resins

Purpose: This study evaluates and compares the effect of printing layer thickness (LT) and post-polymerization time (PPT) on the flexural strength and hardness of three 3D-printed resins after thermal aging. Methods: A bar shape (64 × 10 × 3.3 mm) and a disc shape (15 × 2 mm) were designed for flexural strength and hardness testing, respectively. ASIGA, NextDent, and FormLabs 3D-printed resins were used to print specimens with different LTs (25 µm, 50 µm, and 100 µm). Each thickness group was post-polymerized (PP) for different times (15, 30, 60, and 90 min). All printed specimens were thermally cycled (5000 cycles) and then tested, measuring the flexural strength and hardness using a universal testing machine and Vickers hardness tester, respectively. The data were analyzed using ANOVA and a post hoc Tukey’s test (α = 0.05). Results: A PPT of 90 min showed the highest flexural strength. In comparisons of the LTs, 25 µm and 50 µm significantly increased flexural strength compared with 100 µm, which showed the lowest value for each PPT. The hardness increased as the PPT increased for all materials. In our LT comparison, 25 µm and 50 µm significantly increased the hardness for NextDent and FormLabs resins, while only 25 µm showed high hardness compared with 50 µm and 100 µm for ASIGA. Conclusion: Both parameters (LT and PPT) impact flexural strength and hardness. Increased PPT with the minimum LT is recommended.

Enhancing mechanical properties and density of WC-Co with pressureless sintering via shell structure binder jetting additive manufacturing

The binder jetting (BJT) additive manufacturing (AM) process is suitable for producing complex WC-Co cemented carbide parts. To achieve near-full-density in the final parts, the hot isostatic pressing (HIP) sintering process is typically employed to enhance densification. However, HIP sintering requires high equipment specifications and is relatively more costly compared to conventional pressureless sintering. To improve the density of WC-Co parts printed by BJT AM under the pressureless sintering environment, the shell structure printing method was used in this study. The shell structure printing only jets binder to the model's outer profile, creating a shell that encapsulates the central powder, mitigates binder pyrolysis and residual effects on particle densification, and enhances post-sintering density. In this work, the effect of shell thickness, binder type, and printing layer thickness on the density and mechanical properties of the WC-12Co parts under pressureless sintering conditions were investigated. The results show that the density and mechanical properties of the WC-12Co parts significantly improved with the decreasing shell thickness. Specifically, the WC-12Co printed using shell structure achieves a relative density of over 98% and a transverse rupture strength (TRS) of 1954 MPa after pressureless sintering, a result comparable to BJT printed samples treated with HIP sintering. Moreover, the results indicate using a binder with lower residual carbon content and smaller printing layer thickness has a more positive effect on improving density and mechanical strength when employing the shell structure printing method. Microstructure morphology and phase analysis results indicate that the shell structure printing method does not affect the growth of WC grains in the shell and center regions, nor does it influence its phase composition. The shell structure printing method offers a new approach to the manufacturing of near-full-dense WC-Co materials using the BJT process.

Quantification of the effects of print parameters on the mechanical performance of low force stereolithography parts

The objectives of this work are threefold: (1) quantify the effects that certain print parameters have on the mechanical performance of parts produced by Low Force Stereolithography (LFS), (2) demonstrate the relative impact that certain print parameters have on the mechanical performance of LFS parts and (3) propose theoretical parameter schemas to optimize LFS prints. This work presents the mechanical properties of LFS parts with respect to distinct LFS print parameters, namely print orientation (PO), print layer thickness (LT), post-print cure time (CM) and post-print cure temperature (CT) at three (3) levels apiece. To date, LFS has been largely unstudied; however, as a novel approach with unique engineering material availability, it is important to quantify its overall performance. Using D638-22 to analyze this additive method, it was found that the Segment Modulus (SE), Ultimate Strength (US), percent elongation (%e), Poisson's ratio (ν) and Toughness (T) all varied greatly across the nine (9) distinct sample types designed for the study. Specifically, SE, US, %e, ν and T achieved a minimum/maximum of 331/463 ksi, 4.39/9.07 ksi, 1.20/3.55%, 0.377/.450 and 0.033/.200 ksi, respectively, depending on the parameters chosen. This wide range of property data must be coupled to LFS print parameters if the technology is to be implemented as a viable approach to manufacture end-use or provisional tooling. Furthermore, it is essential to understand the relationship between a given property and a specific parameter. S/N plots were used to quantify both of these relationships. The results indicate that all print parameters influence the mechanical performance of LFS parts.

The effect of printing parameters on the properties of 17-4 PH stainless steel fabricated by material extrusion additive manufacturing

The 17-4PH stainless steel filament was characterised and utilised to study the effect of printing parameters, i.e. printing temperature, layer thickness, infill pattern and extrusion multiplier on the physical properties. The as-printed and as-sintered internal structures were analysed. The results showed that the as-printed density increases with increasing printing temperature and extrusion multiplier and decreasing layer thickness. The use of the line infill pattern also provided slightly higher as-printed density than the concentric infill pattern due to the low fraction of void between deposited paths. After sintering, the trace of these voids can be observed together with smaller-size residual pores from the spaces between powders, which is the nature of the pressureless sintering process. The microstructure of the as-sintered specimens was similar to the typical microstructure of the 17-4PH alloy fabricated by metal injection moulding process, which contains delta ferrite, martensite and Si-rich phases. In additions, the internal void generated during debinding and sintering results in unexpectedly low tensile properties and results in the difference in tensile properties between the concentric and line infill patterns.

Microstructure and properties of tungsten‐40 wt.–% copper composites fabricated by binder jet 3D printing

AbstractIn this work, the tungsten‐copper composites were fabricated by binder jet 3D printing technology. The effects of different printing layer thicknesses (50 μm to 100 μm) on the green density and green strength were investigated. Then, under the optimal layer thickness, the effects of different sintering temperatures (1300 °C to 1600 °C) on the microstructure and densification of tungsten‐40 wt.–% copper composites were studied. The experimental results showed that when the printing layer thickness was set as a lower value (50 μm), the tungsten‐40 wt.–% copper green part had the best strength and its density reached a maximum value of 60.73 %. After sintering for green parts printed with 50 μm layer thickness, the relative density, thermal conductivity and electrical conductivity of sintered parts first increased and then decreased with increasing sintering temperature. In our experiments, the tungsten‐40 wt.–% copper sample fabricated by binder jet 3D printing with a printing layer thickness of 50 μm under a sintering temperature of 1500 °C displayed the best properties, in which the relative density, thermal conductivity and electrical conductivity were 97.04 %, 228 W⋅m−1⋅K−1 and 46.5 % IACS, respectively.

Effects of internal configurations and its processing quality on compressive performance for 3D printed continuous fiber reinforced composites honeycomb sandwich

Continuous fiber reinforced composites (CFRCs) 3D printing technology has the advantage of integrated fabricating for honeycomb sandwich structures, the load-bearing capacity of the fabricated honeycomb sandwich structures still needs to be investigated and improved. This study aims to reveal compression failure modes of 3D printed CFRCs honeycomb sandwich structures with various internal configurations by conducting flatwise compression tests. The deviations of single-layer CFRCs honeycomb cores with different core sizes and core heights and their impacts on the compression failure process were analyzed. A 3D printing method with multilayer cores and core/panel variable printing thickness was proposed, and the effects of multilayer core structure and different core printing parameters on the compressive properties of honeycomb sandwich structures were investigated. The results showed that interlayer cracking caused by core buckling deformation was the leading cause of failure of 3D printed CFRCs honeycomb sandwich structures when subjected to compression. The core buckling deformation could be suppressed by printing multilayer cores and using low core printing thickness, and the compression strength and specific energy absorption of the sandwich structures reached 38.1 MPa and 25.4 kJ/kg, respectively. This study provides guidance for the customization of the 3D printing process of CFRCs honeycomb sandwich structures.

Powder-bed 3D printing by selective activation of magnesium phosphate cement: Determining significant processing parameters and their effect on mechanical strength

The present work addresses powder bed binder jetting additive manufacturing by selective magnesium phosphate cement activation. Despite the potential of this technology to aid the digitalization of the construction industry, the effect of processing parameters on the mechanical performance of printed materials has not yet been studied to generate a guideline for the further development of the technology. Statistical methodologies were used to screen the effect of four printing process parameters (printing speed, layer thickness, raster angle, and build direction on flexural and compressive strength). As the exploited technology works with constant fluid pressure, the physical interpretation of the effect of each factor can be considered taking into account the interactions between the binder materials in the powder bed. Analysis of variance (ANOVA) indicated that printing speed and layer thickness significantly affect mechanical performances. Furthermore, the layout of samples for the printing process is preferable to be parallel the printhead movement. An anisotropic behavior was observed, and the samples subjected to compressive forces parallel to the layer plane possessed lower strength values. This effect can be interpreted as a result of a weak area of low density in between layers, leading to a pronounced delamination under compression.Even though the strength of the printed material is not suitable for a structural concrete, it can be marginally improved by design of experiment and optimized for non-structural applications, such as for porous artificial stone. Design of experiment coupled with ANOVA methods can be used in the future to support the development of novel material mixtures, thus expanding the fields of application of this novel additive manufacturing technology.

Equipment design and parameters recommendation of rubber modified 3D printed asphalt in pavement maintenance

As an advanced technology for pavement crack maintenance with high automation level, high precision and high efficiency, 3D asphalt printing technology can effectively improve worker safety and ensure the stability of maintenance quality. In order to optimize the printing parameters of rubber modified 3D printed asphalt (R-3DPA), a three-axis asphalt 3D printer was developed in this study through the design and selection of each component, and it was used for the 3D printing of R-3DPA strips, layers, and structures. Based on the comparison of continuity, uniformity, and width of R-3DPA strips, the recommended extrusion nozzle diameter, printing temperature, and printing speed parameter combinations were superiorly selected. According to the analysis of filling degree, width error and thickness of R-3DPA layers, the optimal printing strip width was recommended. Through the evaluation of integrity, surface characteristics and accuracy of R-3DPA structures, the suitable printing layer thickness was determined. The test results showed that the three-axis asphalt 3D printer can be used to measure the parameters of R-3DPA, and the printing accuracy and scale meet the requirements. The recommended parameters for R-3DPA are an extrusion nozzle diameter of 2 mm, a printing temperature of 180 °C, a printing speed of 20 mm/s, a printing strip width of 2.25 mm and a printing layer thickness of 0.4 mm, resulting in structures with good integrity and precision.

Silicon carbide ceramics formed by binder jetting: A study focusing on the printing layer thickness and the PIP densification process

Binder jetting (BJ) additive manufacturing has the advantages of high precision, fast forming speed, and no need for supporting structure, which is especially suitable for the forming of metallic and ceramic components with complex structures. In this paper, SiC ceramic parts were obtained by BJ additive manufacturing and precursor impregnation pyrolysis (PIP) cycles. It has been observed that the thickness of the printing layer significantly affects the strength of the SiC green body. The SiC green body exhibited the highest bending strength (3.1 ± 0.2 MPa) and lower dimensional deviation (0.47–1.64 %) when printed with a layer thickness of 50 μm. However, the bending strength of the SiC ceramics (after densification) had little variations when different printing layer thicknesses were utilized. In the subsequent densification process, the density, hardness, and bending strength of SiC ceramics increase as the number of PIP cycles increases obviously, and the flexural strength reached 228.7 ± 14.2 MPa after 9 PIP cycles, while the shrinkage rates in the X, Y, and Z direction were 1.9 %, 2.8 %, and 1.2 %, respectively. In addition, the influence mechanism of printing parameters on the strengths of the green bodies and SiC ceramics was also discussed. Specifically, it was found that with the layer thickness increase, the strengths of SiC ceramics also increase.

Selection strategy of curing depth for vat photopolymerization 3D printing of Al2O3 ceramics

Vat photopolymerization (VPP) 3D printing technology allows the fabrication of complex ceramic structure components through the layer-by-layer stacking strategy. The curing depth is a crucial parameter for the stacking process, as it directly impacts the printing quality. Furthermore, this parameter exerts a profound effect on the final quality of the printed part. However, there is currently a lack of comprehensive research on how the curing depth affects VPP ceramic 3D printing. This study aims to thoroughly evaluate the impact of curing depth parameters on critical aspects of the 3D printing process, including the forming accuracy, surface quality, monomer conversion, resin pyrolysis, interlayer defects, and mechanical properties. The results of our investigation clearly demonstrate the significant influence of curing depth on the precision and performance of VPP 3D printed ceramic parts. Ceramic samples produced with higher curing depth exhibited superior surface quality (Ra<1.6 μm) but lower forming accuracy. Increasing the curing depth improved interlayer adhesion but excessive depth led to a decreased monomer conversion content from 5.2 % to 2.0 % and an internal stress in the green body. Moreover, increasing the curing depth intensified the pyrolysis process and increased the propensity for cracks forming, as confirmed by simultaneous thermal analysis and microstructure observations. The flexural strength of the sintered samples reached its maximum value of 630 MPa at three times the printing layer thickness. This study provides valuable insights for selecting appropriate curing depth parameters in VPP ceramic 3D printing.

Monoliths for gas storage manufactured with precision pore engineering using 3D-printed templates

A fast, customizable, and systematic route for producing activated carbon monoliths for gas storage with low interparticle porosity (9 % to 24 %) containing tailored macro channels is disclosed. The production uses a three-dimensional (3D)-printed polymeric lattice, rich in oxygen, as a sacrificial template. Its interstitial voids are filled with a phenolic resin that is carbonized and activated at 1173 K under carbon dioxide (CO2). Sequential pyrolysis occurs via thermal treatment with the 3D-printed lattice removed first, rendering macro channels with the same shape as the template in accurately placed positions. Resulting in adsorbents with interparticle porosities ranging from 10 % to 23 %, calculated from X-ray micro-computed tomography (micro-CT) images. The axial resolution of these macro channels was similar to the SLA printing layer thickness used of 100 µm. Making it the best resolution attained to date in fabricating monoliths via a 3D-printed sacrificial templating method. Breakthrough experiments indicated healthy macro channel connectivity due to the reduced mass transfer zone. Moreover, excellent mechanical integrity was displayed, with a monolith withstanding 900 N before excessive fracturing occurred despite the presence of macro channels. Therefore, this method emphasizes its use for gas storage applications by enabling the adsorbent material to efficiently utilize the volumetric space while allowing a fast rate of adsorption over the entire structure.

Surface Roughness of Polyetheretherketone Printed by Fused Deposition Modeling: A Pilot Study Investigating the Impact of Print Layer Thickness and Polishing Method

Polyetheretherketone is a high-performance thermoplastic polymer that can be used in 3D printing by fused deposition modeling, and is a promising material for dental applications. Some printing parameters are sensitive and can influence the properties of the printed object. Thus, this work aims to evaluate the influence of the print layer thickness on the surface roughness of polyetheretherketone before and after polishing and to verify the effectiveness of the polishing method used, as well as to compare it with the results obtained using polymethyl methacrylate as the control group. Specimens with different impression layer thicknesses were printed with polyetheretherketone (Group A—0.1 mm and Group B—0.3 mm). Additionally, a control group with polymethyl methacrylate specimens was milled. Roughness evaluation was conducted using a contact profilometer after the specimens had been printed (before polishing). Then, silicon carbide sandpaper was used to polish the surface, and the roughness was reassessed. Differences were observed between specimens regarding the print layer thickness and the roughness, with the 0.3 mm layer thickness showing the lowest roughness values. The results of this pilot study suggest that the surface roughness of fused deposition modeling printed polyetheretherketone is influenced by print layer thickness, with the lowest roughness seen at a thickness of 0.3 mm.

Assessment of the trueness of additively manufactured mol3% zirconia crowns at different printing orientations with an industrial and desktop 3D printer compared to subtractive manufacturing

ObjectivesThis study endeavours to investigate the effect of printing orientation on the trueness of additively manufactured molar zirconia crowns. The areal surface roughness and the characteristics of the marginal regions of the crowns were also considered. MethodsTwelve molar crowns were manufactured at 0°, 45°, and, 90° printing orientations in a Lithoz and AON zirconia printer, respectively. Twelve milled crowns were used as a comparison. Samples were scanned and analysed in metrology software to determine the trueness of the groups. Regions of interest were defined as the margins, intaglio surface and contact points. Areal surface roughness and print layer thickness were further analysed using a confocal laser scanning microscope. ResultsThe results indicate that there are clear differences between the investigated desktop (AON) and industrial (Lithoz) 3D printer. The 45° Lithoz group is the only sample group showing no significantly different results in trueness for all regions analysed compared to the milled group. Areal surface roughness analysis indicates that the print layers in the marginal regions are within clinically tolerable limits and surface characteristics. ConclusionsThe printing orientation for zirconia crowns is critical to trueness, and differences are evident between different AM apparatuses. Considerations for design and orientation between different apparatuses should therefore be considered when utilising direct additive manufacturing processes. The areal surface roughness of the marginal regions is within acceptable clinical limits for all manufacturing processes and print orientations considered. Clinical significanceThe materials and apparatuses for additive manufacturing of zirconia crowns are now clinically acceptable from the perspective of the trueness of a final crown for critical functional surfaces and areal surface roughness of the marginal regions.

Morphology analysis and process optimization of μ-SLA 3D manufactured micro-nano conic structure

PurposeThis paper is devoted to prepare micro-cone structure with variable cross-section size by Stereo Lithography Appearance (SLA)-based 3D additive manufacturing technology. It is mainly focused on analyzing the forming mechanism of equipment and factors affecting the forming quality and accuracy, investigating the influence of forming process parameters on the printing quality and optimization of the printing quality. This study is expected to provide a µ-SLA surface preparation technology and process parameters selection with low cost, high precision and short preparation period for microstructure forming.Design/methodology/approachThe µ-SLA process is optimized based on the variable cross-section micro-cone structure printing. Multi-index analysis method was used to analyze the influence of process parameters. The process parameter influencing order is determined and validated with flawless micro array structure.FindingsAfter the optimization analysis of the top diameter size, the bottom diameter size and the overall height, the influence order of the printing process parameters on the quality of the micro-cone forming is: exposure time (B), print layer thickness (A) and number of vibrations (C). The optimal scheme is A1B3C1, that is, the layer thickness of 5 µm, the exposure time of 3000 ms and the vibration of 64x. At this time, the cone structure with the bottom diameter of 50 µm and the cone angle of 5° could obtain a better surface structure.Originality/valueThis study is expected to provide a µ-SLA surface preparation technology and process parameters selection with low cost, high precision and short preparation period for microstructure forming.

Design and fabrication of bioinspired pattern driven magnetic actuators

Additive manufacturing (AM) has drawn significant attention in the fabrication of soft actuators due to its unique capability of printing geometrically complex parts. This research presents the design and development of an AM process for bioinspired, deformable, and magnetic stimuli-responsive actuator arms. The actuator arms were fabricated via the material extrusion-based AM process with magnetic particle-polymer composite filaments. Inspired by the rhombus cellular structure found in nature, different design parameters, such as the line width of the interior rhombus sides, and 3D printing parameters were studied and optimized to fabricate actuator arms that exhibit enhanced flexibility while being magnetically actuated. The trigger distance and deformation experiments revealed that the width of the rhomboids’ sides played a critical role in magnetic and bending properties. It was found that the sample with a line width of 550 µm and printing layer thickness of 0.05 mm had the maximum deflection with a measured bending angle of 34 degrees. The magnetic property measurement exhibited that the sample with a line width of 550 µm showed the maximum magnetic flux density of 3.2 mT. The trigger distance results also supported this result. A maximum trigger distance of 8.25 mm was measured for the arm with a line width of 550 µm. Additionally, tensile tests showed that the sample exhibited a 17.7 MPa tensile strength, 1.8 GPa elastic modulus, and 1.3% elongation. Based on these results, we successfully fabricated a 3D printed magnetic gripper with two rhombus cellular structured arms which showed grasping and extensive load lifting capability (up to ∼140 times its weight).