SLS Technology Research Articles

Dimensional Accuracy in 3D Printed Medical Models: A Follow-Up Study on SLA and SLS Technology

Background: With the rise of new 3D printers, assessing accuracy is crucial for obtaining the best results in patient care. Previous studies have shown that the highest accuracy is achieved with SLS printing technology; however, SLA printing technology has made significant improvements in recent years. Methods: In this study, a realistic anatomical model of a mandible and skull, a cutting guide for mandibular osteotomy, and a splint for orthognathic surgery were replicated five times each using two different 3D printing technologies: SLA and SLS. Results: The SLA group had a median trueness RMS value of 0.148 mm and a precision RMS value of 0.117 mm. The SLS group had a median trueness RMS value of 0.144 mm and a precision RMS value of 0.096 mm. There was no statistically significant difference in RMS values between SLS and SLA technologies regarding trueness. Regarding precision, however, the RMS values for SLS technology were significantly lower in the splint and cutting guide applications than those printed with SLA technology. Conclusions: Both 3D printing technologies produce modern models and applications with equally high dimensional accuracy. Considering current cost pressures experienced by hospitals, the lower-cost SLA 3D printer is a reliable choice for point-of-care 3D printing.

Stress-adaptive femur bionic triple periodic minimal heterostructures manufactured by SLS technology with excellent mechanical properties

Inspired by the morphology and material distribution characteristics of femoral trabecular bone, four types of biomimetic triply periodic minimal surface (TPMS) heterogeneous structures were designed. Biomimetic samples were fabricated using selective laser sintering technology for quasi-static compression and impact testing. A comparative study of the planar compression performance and impact resistance of the biomimetic TPMS heterogeneous structures was conducted. The results showed that the heterogeneous component composition improved the strength performance of the original structure by over 25 %, and enhanced the overall energy absorption characteristics by more than 23.5 %. By leveraging the mechanical coupling properties of heterogeneous materials, the strength and energy absorption performance of the original structure were increased by over 20 %. Additionally, combining additive manufacturing technology, a novel stress-adaptive porous component design for practical engineering applications was developed. In conjunction with bicycle helmet design, the stress-adaptive component modeling method demonstrated excellent performance in modeling flexibility and mechanical strength. By reasonably combining different types of materials, the heterogeneity of materials can fully utilize their respective advantages and compensate for deficiencies, thereby creating materials with superior mechanical properties.

Brucine Sulfate, a Novel Bacteriostatic Agent in 3D Printed Bone Scaffold Systems.

Bacterial infection is a common complication in bone defect surgery, in which infection by clinically resistant bacteria has been a challenge for the medical community. Given this emerging problem, the discovery of novel natural-type inhibitors of drug-resistant bacteria has become imperative. Brucine, present in the traditional Chinese herb Strychnine semen, is reported to exert analgesic and anti-inflammatory effects. Brucine's clinical application was limited because of its water solubility. We extracted high-purity BS by employing reflux extraction and crystallization, greatly improved its solubility, and evaluated its antimicrobial activity against E. coli and S. aureus. Importantly, we found that BS inhibited the drug-resistant strains significantly better than standard strains and achieved sterilization by disrupting the bacterial cell wall. Considering the safety concerns associated with the narrow therapeutic window of BS, a 3D BS-PLLA/PGA bone scaffold system was constructed with SLS technology and tested for its performance, bacteriostatic behaviors, and biocompatibility. The results have shown that the drug-loaded bone scaffolds had not only long-term, slow-controlled release with good cytocompatibility but also demonstrated significant antimicrobial activity in antimicrobial testing. The above results indicated that BS may be a potential drug candidate for the treatment of antibiotic-resistant bacterial infections and that scaffolds with enhanced antibacterial activity and mechanical properties may have potential applications in bone tissue engineering.

Research and implementation of large-area sintering technology based on image-shaped laser

PurposeSelective laser sintering (SLS) is an essential technology in the field of additive manufacturing. However, SLS technology is limited by the traditional point-laser sintering method and has reached the bottleneck of efficiency improvement. This study aims to develop an image-shaped laser sintering (ISLS) system based on a digital micromirror device (DMD) to address this problem. The ISLS system uses an image-shaped laser light source with a size of 16 mm × 25.6 mm instead of the traditional SLS point-laser light source.Design/methodology/approachThe ISLS system achieves large-area image-shaped sintering of polymer powder materials by moving the laser light source continuously in the x-direction and updating the sintering pattern synchronously, as well as by overlapping the splicing of adjacent sintering areas in the y-direction. A low-cost composite powder suitable for the ISLS system was prepared using polyether sulfone (PES), pinewood and carbon black (CB) powders as raw materials. Large-sized samples were fabricated using composite powder, and the microstructure, dimensional accuracy, geometric deviation, density, mechanical properties and feasible feature sizes were evaluated.FindingsThe experimental results demonstrate that the ISLS system is feasible and can print large-sized parts with good dimensional accuracy, acceptable geometric deviations, specific small-scale features and certain density and mechanical properties.Originality/valueThis study has achieved the transition from traditional point sintering mode to image-shaped surface sintering mode. It has provided a new approach to enhance the system performance of traditional SLS.

Comparison of Quality of Porous Structure Specimens Produced by Different Additive Technologies and from Different Materials

Lattice and gyroid structures are often subjected to additive technologies to produce various types of products, and the current market has a number of 3D printers that can be used for their production. The quality of the products produced in this way can be assessed on the basis of technical parameters and the filament used. Such an approach, however, is insufficient. In terms of quality, other product parameters need to be assessed, such as the surface texture and the internal structure’s porosity. For such an assessment, we can use the industrial tomography method and the method of roughness measurement via an optical microscope. The paper presents research on the assessment of the surface texture and porosity in lattice and gyroid structures. For the research, two types of test specimens—a specimen with a lattice structure and a specimen with a gyroid structure—were prepared. The obtained results proved that the 3D printing technology directly impacted the surface texture and porosity. For experimental specimens produced by SLS technology, we found that it was very important to carefully remove the excess powder, as unremoved powder can significantly affect the porosity results. For specimens produced by FDM technology, the research confirmed that some “gaps” between the layers were not pores but defects created during specimen production. When analyzing the surface using the Alicon Infinite G5 optical microscope, we found that the measured roughness results were directly impacted by the specimen’s surface color, the structure’s geometry, and the ambient light, which was confirmed by a red lattice experimental specimen, the surface of which could not be scanned. Based on the above, it can be stated that the selection of 3D technology for additive production needs must be given adequate attention regarding the quality of the created structures and textures.

Evaluation of the mechanical properties of polyamide 12 regarding different percentages of reused material in the selective laser sintering process

PurposeAdditive manufacturing (AM) has been one of the most highlighted processes of the last few years. AM prints complex parts and items from 3D files regarding different materials, such as polymers. Moreover, there are different AM techniques available for polymers, such as selective laser sintering. In the SLS technology, polyamides 11 and 12 lead 88% of the market. These materials are high-cost and use an average of 50% of virgin material at each printing. It is possible to use lower rates of virgin material, but at least 30% is recommended. Low rates of virgin material decrease mechanical properties.Design/methodology/approachThis study aims to evaluate the influence on the mechanical properties of the percentage of reused PA12 in parts manufactured by the SLS process. The specimens of PA12 were manufactured with a percentage of virgin/reused polymer of 50/50, 40/60, 30/70, 20/80 and 10/90. We considered three distinct printing directions to compare the mechanical properties of the specimens: horizontal, perpendicular and vertical.FindingsThe results showed that when the percentage of reused material increases, the tensile strength limit (TSL), flexural strength limit and Shore D hardness decrease. Another aspect visualized was the fragile behavior presented in the vertical specimens. In addition, DSC analysis indicated a 2% reduction of crystallinity. Scanning electron microscopy images revealed spherical voids and unfused particles of PA12 at the fracture of tensile test specimens. The material thermal history and unfused particles could decrease the material properties.Originality/valueWe observed that the mechanical properties, such as the TSL, flexural strength limit and hardness, decrease as the percentage of reused material increases. In addition, the process presented a printing-direction dependence, where the vertical direction presented as the more brittle between the ones used.

Development of a Prototype of a Protective UV-C Half-Face Mask with Implementation of Additive Technology

The authors of this manuscript present development of a prototype protective UV-C half-face mask. The first stage of this study focuses on proposing a UV-C half-face mask design and the second phase investigates the quality of printings, 3D/2D roughness and porousness of three different printed samples of PA12. Development of the protective half-face mask used the non-destructive technology of 3D scanning of the human body by the Ein Scan scanner. As a part of the experiment, three samples were prepared with Sinterit Lisa, EOS Formiga and HP jet fusion printers. SLS and MJF technology were used during the experiment. The experimental observation of the structure of the surface was secured using the Alicona Infinite focus G5 device. The conclusions present the study's results and the authors' recommendations for other developers dealing with the development of the protective face masks.

An Nylon lattice structure with improved mechanical property and energy absorption capability

To study the mechanical behavior and energy-absorption capability, different lattices structures were designed and fabricated by using SLS technology with a raw material of Nylon. The quasi-static compression experiment and finite element simulation revealed the mechanical response and deformation mechanism of these structures. Meanwhile, the energy absorption capacity of the lattices structure was assessed by the impact resistance and corresponding calculations of specific energy absorption. The different design schemes were compared and analyzed under the same conditions. The results show that a minimal surface structure (MSS) has the best performance of compression properties. The designed composite scheme composed of the MSS and the BCC structures effectively enhances the impacting-bearing capability and improves the energy absorption performances.

Microstructure control of SiCw/SiC composites based on SLS technology

The preparation of SiCw/SiC materials was realized by SLS technology. The effect of SiC powder size on the number and size of SiC whisker formation was investigated. The tortuosity and diameter of open pores are introduced to modify the classical molecular collision model, and the relationship model between the growth rate of SiC whisker and porosity was established. The influence mechanism of powder size on the number of whisker growth was revealed. According to the model, the number of in-situ whisker growth in powder can be calculated, and the calculated results by using this model agreed with the test results. So it is suitable for in-situ whisker microstructure control under SLS technology, and also suitable for other 3D printed whisker in-situ reinforced ceramic material systems. This is of great significance to expand the application of 3D printing ceramic matrix composites.

Weathering performance and structural characterization of limestone–polyethersulfone composites

Using limestone powder as an aggregate and polyethersulfone (PES) powder as a binder, the limestone: PES composite material, LPES, with a mass fraction ratio of 1:10 was prepared using the SLS technology. The sintered parts were subjected to the xenon lamp aging, thermal analysis, cross-sectional scanning electron microscope (SEM) tests. The results showed that the LPES material sintered parts aged slower, and had a longer service life. Compared with the sintered parts of pure PES material after aging for 10 weeks, the service life of LPES was increased by 38.91%, and with the filling of limestone powder material, the decomposition temperature and heat resistance level of LPES composites were effectively improved. In addition, the heat absorption of LPES composites during decomposition was reduced.

An Innovative Project of a Bionic Robot for Social Applications in Felinotherapy

The paper describes an innovative design of a bionic robot for applications in felinotherapy supporting hospital and home psychotherapeutic treatment of bedridden children and adults. The project was engineered by biomimicrating a biological cat, reaching its robotic model. Particular attention in this process was devoted to capturing the essence of feline motorics behavior and the possibility of mapping them in a mechatronic model. The geometry, kinematics and kinetics of this model were analyzed, creating assumptions for its practical implementation in the real mechanism of cat skeleton movement. The used software used the topology of elements in Autodesk Fusion 360 Simulation workspace by performing the critical elements of the mechatronic model in print using SLS technology. The work was also supported by a graphical simulation in the PyBullet environment.

A Pilot Study on Machining Difficult-to-Cut Materials with the Use of Tools Fabricated by SLS Technology.

The growing use of contemporary materials in various industrial sectors, such as aerospace, automotive, as well as the oil and gas industry, requires appropriate machining methods and tools. Currently, apart from the necessity to obtain high-dimensional and shape accuracy, the efficiency and economic aspects of the selected manufacturing process are equally important, especially when difficult-to-cut materials, such as hard and brittle ceramics, have to be machined. In the research presented in this paper, a prototype tool fabricated from polyamide powder by the SLS method was used in flat-lapping of Al2O3 ceramics, showing the promising potential and efficacy of rapid tooling and manufacturing in the area of abrasive machining. The influence of the selected input process factors, such as machining time, the type of abrasive suspension, kinematic parameters, and unit pressure, on technological effects, was analyzed. The microscopic observations of the active surface of the prototype tool showed its reinforcement with loose diamond abrasive particles (size D107), resulting in the effective material removal and improved surface finish of Al2O3 ceramic samples. The directions for further development of tools fabricated by the SLS method for applications in abrasive machining were also envisaged by the authors.

3D printing technology based on nanometer materials in mechanical automation processing

With the rapid development of various industries, the machinery manufacturing industry has been constantly carrying out reform and innovation, among which the introduction and use of technology is constantly increasing, so as to promote the development level of the machinery manufacturing industry. As the most cutting-edge and most potential technology, 3 D printing technology is an important direction of the development of mechanical automation processing. The purpose of this paper is to study the application of 3 D printing technology based on nanomaterials in automatic machining. This paper first introduces the basic concept and working principle of 3 D printing technology, and analyzes the types of 3 D printing technology. Then the classification and preparation of nanomaterials are introduced. This paper also studies the application of 3 D printing technology based on nanomaterials in mechanical automation. The experimental materials in this paper select gold nanoparticles of nanomaterials, and use SLS technology of 3 D printing to degrease and sintering gold nanoparticles. In this paper, the performance of the embryo was tested through two processes of degreasing and sintering, and the experimental results showed that the application of 3 D printing technology based on nanomaterials in mechanical automatic processing has certain practical significance. In this paper, the degreasing rate of the billet at different degreasing temperature is analyzed. When the degreasing temperature is 500 °C, the degreasing rate of the billet reaches 94%.

Hybrid of multi‐dimensional fillers for thermally enhanced polyamide 12 composites fabricated by selective laser sintering

AbstractSelective laser sintering (SLS) is an additive manufacturing technology that can provide a novel strategy to manufacture complex polymer‐based composites with tailored properties. In this study, polyamide 12 (PA12) composite powders based on Al2O3, boron nitride (BN), and carbon nanotubes (CNTs) were prepared via a two‐step mixing approach. Morphology characterization techniques indicated that the fillers were uniformly dispersed in the PA12 matrix as expected. Under the optimum 3D‐printing parameters, the fabrication of SLS parts with high filler loading could be obtained. With 40 wt% Al2O3, 8 wt% BN, and 2 wt% CNT hybrid fillers, the thermal conductivity of PA12 composites could reach 1.09 W/mK. It could be attributed to the synergistic effect of multi‐dimensional fillers to form dense and continuous thermal conduction paths. The factors influencing the performance of PA12 composites such as melting and crystallization behaviors, dielectric properties, and mechanical properties were also discussed. The results show that these composites have favorable dielectric and mechanical properties. Overall, the PA12 composites fabricated by SLS technology in this study exhibit excellent thermal management ability.

Friction and wear properties of oriented Polyamide 12 objects manufactured by SLS Technology

Friction and wear properties of oriented Polyamide 12 objects manufactured by SLS Technology

The combination of Al2O3 and BN for enhancing the thermal conductivity of PA12 composites prepared by selective laser sintering.

A powder-based 3D printing technology, selective laser sintering (SLS), is a novel strategy of manufacturing complex components with specially tailored properties, including mechanical properties, as well as thermal and electrical conductivity. In this study, the effect of incorporating Al2O3 particles and BN plates on the thermal conductivity of PA12 composites was investigated. PA12 composite powders, which can be well applied to SLS, were prepared via a two-step approach to mixing. Morphology characteristics demonstrated that the fillers dispersed uniformly in the PA12 matrix, as expected. With 35 wt% Al2O3 and 15 wt% BN hybrid fillers, the tensile strength had the potential to reach 25.7 MPa, while the thermal conductivity could reach 1.05 W m−1 K−1, 275% higher than that of pure PA12. In addition, the study investigated the effects of filler content on the thermal stability and mechanical properties whilst analysing the melting and crystallisation behaviours of SLS components. The results demonstrate that these composites have favourable thermal stability and exhibit no severe deterioration in mechanical properties. The PA12 composites prepared in this work therefore illustrated vast potential in thermal management materials.

A new design approach for customised medical devices realized by additive manufacturing

The aim of this work is the design of a new customised elbow orthosis completely realized by Additive Manufacturing and the development of generative algorithms for parametric modelling and creation of 3D patterns to be adapted to the CAD model. This work describes a method to perfect the design of a custom elbow orthosis. A reverse engineering approach has been used to digitalize the patient’s arm and the subsequent CAD modelling of the structure of the custom elbow orthosis has been performed. In particular, two algorithms have been implemented for the creation of 3D patterns and Voronoi tessellations. Subsequently, FEM analyses have been carried out to validate the design. Finally, a prototype of the elbow orthosis with Voronoi tessellation has been realized by means of the SLS technology. The results obtained have demonstrated that the implemented algorithm solved the problems found during CAD modelling with conventional software. Furthermore, the results of FEM analyses have validated the design choices. All this allowed realizing the prototype by AM technologies without problems. Moreover, the new proposed modelling approaches allows creating, in an interactive way, patterns on complex surfaces. The results of this research activity present innovative elements of originality in the CAD modelling sector, which can contribute to solving problems related to the modelling for Additive Manufacturing. Furthermore, another innovative characteristic of the device is the use of torsion springs that simulate the action of physiotherapists during exercises for patient rehabilitation.

Influence of Tumbling Bodies on Surface Roughness and Geometric Deviations by Additive SLS technology

This research focusing on influencing the surface structure and its geometric deviations from the CAD model after various tumbling of bodies at constant parameters of the tumbling machine. The purpose of determining the actual effect on the resulting surface before and after the tumbling pro-cess, which tumbling body causes the selection of a larger grain or compaction of the surface layer. The research outputs are thermographic maps and geometric deviations measured using CAD mod-els. The experimental line was at VĹ B - TU Ostrava, with the help of the PROTOLAB 3D printing center, there was an experimental sample in your game. Measurement of access in the metrology laboratory on CMM Wenzel LH 65 X3Premium and optical heads Shapetracer II.

Rheological Properties of Polyamide PA 2200 in SLS Technology

Rheological Properties of Polyamide PA 2200 in SLS Technology

Evaluation of the Dimensional Accuracy of 3D-Printed Anatomical Mandibular Models Using FFF, SLA, SLS, MJ, and BJ Printing Technology.

With the rapid progression of additive manufacturing and the emergence of new 3D printing technologies, accuracy assessment is mostly being performed on isosymmetric-shaped test bodies. However, the accuracy of anatomic models can vary. The dimensional accuracy of root mean square values in terms of trueness and precision of 50 mandibular replicas, printed with five common printing technologies, were evaluated. The highest trueness was found for the selective laser sintering printer (0.11 ± 0.016 mm), followed by a binder jetting printer (0.14 ± 0.02 mm), and a fused filament fabrication printer (0.16 ± 0.009 mm). However, highest precision was identified for the fused filament fabrication printer (0.05 ± 0.005 mm) whereas other printers had marginally lower values. Despite the statistically significance (p < 0.001), these differences can be considered clinically insignificant. These findings demonstrate that all 3D printing technologies create models with satisfactory dimensional accuracy for surgical use. Since satisfactory results in terms of accuracy can be reached with most technologies, the choice should be more strongly based on the printing materials, the intended use, and the overall budget. The simplest printing technology (fused filament fabrication) always scored high and thus is a reliable choice for most purposes.