Selective Laser Sintering Method Research Articles

Method for profile reconstruction of the workpiece surface during groove micromilling

A leading trend in modern industry is hybrid manufacturing methods. The intention is to integrate additive and subtractive methods into a single machine. In such a process, it is difficult to evaluate the quality of the manufactured component between successive processes. A solution that would make it possible to determine the quality of a component produced by incremental technologies on the basis of forces recorded in a machining process is not yet available. In the present study, an attempt was made to reconstruct the surface of the machined workpiece solely on the basis of recorded forces during the groove micromilling process. A workpiece with a known surface geometry in the form of a sinuous wave was machined. The geometry of the workpiece corresponded to a structure typical of the selective laser sintering method for metallic powders. A process conducted with two different axial cutting depths was considered. The reconstructed surface profiles were evaluated by comparative analysis with the real machined surface.

Study on Resin-based 3D Printed Product for Spin Casting Mold Making

Spin casting (centrifugal rubber mold casting) is well known process to produce castings by utilizing inertia. A vulcanized rubber mold is typically used by spinning it at an optimum speed along its central axis. There are many factors influence the quality of casting product, including the quality of mold, the temperature of molten material, the speed and duration of rotation, as well as the pressure upon the mold. This research aims to investigate the quality of casting product when a resin-based 3D printing is utilized to make a model for vulcanized rubber mold. The model is designed by using CAD software and printed layer by layer by using Selective Laser Sintering (SLS) method. Curing process is employed in order to harden the model before placed in the disc-shape silicone rubber. The rubber is then vulcanized so that the mold is formed. Standard edge gate and straight runner are then made to let the molten material flow during casting process. Zinc alloy is used as raw material in the casting process with five variations of rotation speed. Based on the experiment results it is observed that the resin-based 3D printed product can be used as a master model in rubber mold making with some limitations. The resin could not maintain its shape due to the high temperature and pressure during vulcanization process. However, for simple design without any need of very small and detail features, the resin-based 3D printed product still can be used as an alternative.

3D Printing of a Tidal Turbine Blade Using Two Methods of SLS and FFF of a Reinforced PA12 Composite: A Comparative Study

This study scrutinizes the thermomechanical dynamics of 3D-printed hydrofoil blades utilizing a carbon and glass bead-reinforced thermoplastic polymer. Comparative analyses underscore the pivotal role of polymer reinforcement in augmenting mechanical strength and mitigating deformation and residual stress. The investigation elucidates the expeditious and cost-efficient manufacturing potential of low-cost Fused Filament Fabrication (FFF) printers for small-scale blades, revealing exemplary mechanical performance with nominal deflection and warping in the PA12-CB/GB printed blade. A comprehensive juxtaposition between Selective Laser Sintering (SLS) and FFF printing methods favors SLS due to its isotropic properties, notwithstanding remediable warping. Emphasizing the rigorous marine environment, the study cautions against the anisotropic properties of FFF-printed blades, despite their low mechanical warping. These discernments contribute to hydrofoil design optimization through numerical analysis, shedding light on additive manufacturing’s potential for small blades in renewable energy, while underscoring the imperative for further research to advance these techniques.

An innovative three-dimensional printed titanium implant with a biomimetic structure design for promoting osseointegration potential

The present study aimed to investigate the surface characteristic, biocompatibility, and bone regeneration behavior of an innovative three-dimensional (3D) printed titanium (Ti) implant with a biomimetic cancellous bone-like spherical particle porous structure (3DBCP-Ti) through scanning electron microscopy, X-ray diffractometry, static contact angle goniometry, cytotoxicity assay, and rabbit model. The analytical results showed that the 3DBCP-Ti implant with an average pore size of 400 ± 10.5 μm can be fabricated using a selective laser sintering method. The 3DBCP-Ti implant not only possessed excellent wettability (13.5 ± 1.7°) but also presented superior cell viability (97 ± 1.5 %) in vitro. After implantation for 4 weeks, the bone mineral density of the 3DBCP-Ti implant (0.14 ± 0.02 mg/cm3) exhibited a slightly higher value than the control implant (0.13 ± 0.03 mg/cm3). Moreover, histological results also indicated that the new bone formation area of the 3DBCP-Ti implant (43.9 ± 7.0 %, *p < 0 0.05) significantly enhanced as compared with the control (23.5 ± 4.6 %) and blank (18.2 ± 1.4 %) groups at week 12 post-implantation. Accordingly, these findings demonstrate that the innovative 3DBCP-Ti implant has the potential to promote osseointegration at early-stage implantation for dental, orthopedic, and neurosurgical applications.

Influence of post-processing treatment on the surface roughness of polyamide PA12 samples manufactured using additive methods in the context of the production of orthoses

Additive techniques are gaining popularity, primarily due to the emergence of new 3D printing methods, advancements in 3D printers, and the availability of innovative materials. Models produced using additive processes can undergo additional post-processing and dyeing to modify their functional and visual properties. This article presents the results of surface roughness tests conducted on samples made of polyamide PA12, using the Selective Laser Sintering (SLS) and HP MultiJet Fusion (MJF) methods. Regarding the processing methods, chemical surface treatment contributed to reducing Ra and Rz parameters by about 80% for both analyzed printing methods, while mechanical surface treatment resulted in a reduction of approximately 40% for SLS samples and 30% for MJF samples. On the other hand, dyeing and applying an antibacterial coating did not significantly affect the Ra and Rz parameter values. Considering the obtained results, the recommended manufacturing method for orthosis is the MJF method, and the finishing process should include mechanical treatment followed by dyeing.

Design and Behavior of Lightweight Flexible Structure with Spatial Pattern Reducing Contact Surface Fraction.

Flexible structures are increasingly important in biomedical applications, where they can be used to achieve adaptable designs. This paper presents a study of the design and behavior of 3D-printed lightweight flexible structures. In this work, we focus on the design principles and numerical modelling of spatial patterns, as well as their mechanical properties and behavior under various loads. Contact surface fraction was determined as the ratio of the surface area of the printed pattern to the surface area of the entire curved surface. The objective of this work is to design a spatial pattern reducing contact surface fraction and develop a non-linear numerical model evaluating the structure's stiffness; in addition, we aimed to identify the best design pattern with respect to its stiffness:mass ratio. The experimental verification of the numerical model is performed on 3D-printed prototypes prepared using the Selective Laser Sintering (SLS) method and made of Nylon-Polyamide 12. The obtained results provide insights into designing and optimizing lightweight external biomedical applications such as prostheses, orthoses, helmets, or adaptive cushions.

Application of a Pantographic Design Obtained by the Method of SLM Printing and Study of the Influence of Postprocessing with Application of Damping Coatings

To deal with residual stresses that arise after the application of the selective laser sintering method, in this article the heat treatment method according to the State Standard and vibration tumbling in a drum with ceramic “chips” are chosen. During operation, various vibrations occur, which lead to the destruction of the structure. To deal with vibrations of this kind, it is proposed to apply coatings to the structure. Such coatings increase the resistance to oxidation, corrosion, etc. In addition, they absorb vibrations (damping), thus removing resonance. At the same time, the service life of a coated product relative to an uncoated part is guaranteed to be 5–20% higher.

Farklı Katkılı Üretim Yöntemlerinin Dayanım, Yüzey Kalitesi Ve Maliyetlerinin Karşılaştırılması

Additive manufacturing is a manufacturing method that includes systems that produce using many different methods. The most widely used and accessible methods of additive manufacturing can be listed as Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS) and UV light assisted Stereolithography (SLA). Today, it is quite easy to produce thermoplastic products suitable for direct use in low quantities with these three methods. In addition, the production success of the parts produced in geometric difficulties also increases this demand. The most important problem is the lack of sufficient studies and information about the strength limits, surface quality and costs of the parts produced for additive manufacturing methods with such advantages. In this study, the comparison of three different production methods in terms of surface roughness, strength and cost is discussed in order to eliminate this deficiency in the literature. For this purpose, the tensile strength and surface roughness values of the samples produced using FDM, SLS and SLA methods were determined. In addition, cost analyzes were made depending on the production time of the produced samples. In the study, the lowest cost was obtained in the SLA material with a value of $ 0.19. Again, the lowest values were obtained for the samples produced from SLA material, with a production time of 17 minutes and a surface roughness of 1.96µm compared to other methods. However, when evaluated in terms of strength, the highest strength value was obtained as 57.67 N/mm2 in the FDM method.

Powders of rGO-coated polyamide with special electrical properties for SLS 3D printing

Developing new polymer composites with special properties for 3D printing is one of the most attractive tasks. In our study, we have developed new polymer powders based on rGO-coated polyamide suitable for Selective Laser Sintering (SLS) printing. The obtained materials were characterized using optical microscopy, UV-Vis spectroscopy, scanning electron microscopy and dielectric spectroscopy. The size distribution of the powder particles, the angle of rest after an avalanche, the compactibility (Hausner ratio), the optical properties (absorption and transmission) of the powder monolayer, and the electrical conductivity of the obtained materials have been studied. It has been shown that the developed powders are suitable for the use in the framework of the SLS method, and can be applied to remove static electricity, as well as in reflective screens for electromagnetic radiation.

Dry sliding wear behavior of energy density dependent PA 12/Cu composites produced by selective laser sintering

Abstract The selective laser sintering process is widely used to fabricate polyamide matrix composites. Although various reinforcements are used to produce polyamide matrix composites, metallic-based reinforcements are used to improve the mechanical properties of the structure. Also, selective laser sintering process parameters significantly affect the microstructural and mechanical properties of the composite products. In this study, polyamide 12 (PA 12) matrix composites were produced with Cu particulates by selective laser sintering methods using various energy density values. Moreover, dry sliding wear of the energy density dependent PA 12/Cu composites was investigated. Worn samples were characterized by scanning electron microscopy and 2D profile analysis. The examinations revealed that the lower energy density values improve the microstructural properties and wear behavior of the PA 12/Cu composites. It was obtained that the lowest energy value provides the highest wear resistance for the PA 12/Cu composites.

Analysis of the possibility of using additive technologies in basic parts manufacturing

The purpose of the article is to choose a selective laser sintering method suitable for basic parts manufacturing, as well as to analyze mechanical characteristics of parts obtained using selective laser sintering, depending on the technology of their production. Basic parts manufacturing is a complex and expensive process which includes casting or welding, milling of base surfaces, and boring of holes. As a rule, body is the largest part of the structure, and accuracy of its base surfaces manufacturing directly affects performance of the entire mechanism. Method of producing blank parts is of paramount importance in body manufacturing. Parts of this type must ensure precision of the relative position of individual elements, both at rest and in the dynamic mode of machine operation. At the same time, it is known that all methods of blank parts production are characterized by the presence of residual stresses in the blank part. Gradually relaxing, these stresses “come out” in the form of deformations, which leads to displacement of parts and units of the entire mechanism, and a change in their interaction. This directly affects performance and resource of the entire machine.

Study of manufacturing defects on compressive deformation of 3D-printed polymeric lattices

This paper studies theoretical, numerical, and experimental studies on static compression behaviour of polyamide 12 body-centred cube (BCC) lattices manufactured using the selective laser sintering (SLS) method. In the analytical formulation, the influence of imperfections that happened during 3D printing such as material overlapping in the vicinity of filament joints is considered to provide predictions of mechanical properties of a macro lattice structure. Finite element (FE) models of the BCC lattices are performed to predict the compressive behaviour and deformation localisation of filaments. In order to determine a material model and input parameters for FE simulation of the lattice cubes, an individual 3D-printed filament is subjected to transverse compressive loading utilising a custom-made filament compression rig. Then, true experimental stress and strain data are generated that are imported into an inverse calibration technique using MCalibration software to determine the material parameters for the FE simulation. A series of BCC lattice cubes were printed using the SLS method. Compression experiments were conducted utilising digital image correlation (DIC) techniques in order to determine localisation of deformations and strains and validate the material properties obtained by the analytical modelling and numerical simulations. Good agreements are observed among the analytical, numerical, and experimental results. The results show that effect of filament defects should be taken into account to find the accurate responses in analytical model and FE simulation.

Radar-stealth and load-bearing corrugated sandwich structures with superior environmental adaptability

The engineering design of lightweight multifunctional composite structures is an attractive research subject with enormous potential in the aerospace and marine fields. Nevertheless, the mechanical and electromagnetic performance of variable-curvature structures has been seldom investigated. Herein, a novel multifunctional sinusoidal corrugated sandwich structure with impedance-type frequency selective surface (FSS) is proposed to provide superior out-of-plane load-bearing capacity and broadband microwave stealth performance. A precise theoretical model is proposed to predict the out-of-plane compressive strength of sinusoidal corrugated structures. The model is based on the Timoshenko beam theory and a modified plastic hinge theory, considering the actual stress distribution on the cross-section. The selective laser sintering (SLS) method is employed to fabricate a series of specimens with different structural parameters. The simulation analysis and experimental results suggest that the proposed mechanical model possesses high precision and wide applicability. The proposed multifunctional sandwich structure has an average ultimate compressive strength of 1.106 MPa and broadband microwave stealth (maximum reflectivity of −8.8 dB in 2–18 GHz). Environmental factors are found to have little effect on microwave reflectivity, including out-of-plane compressing (2 dB), frosting (0.5 dB) and holing (0.5 dB). The present study provides an example of broadband microwave stealth and load-bearing structure with superior environmental adaptability.

Systematic Literature Review on Methodology and Manufacturing Process of Personalized Tablet using Selective Laser Sintering Technology

3-dimensional printing (3DP) technology has garnered interests as a novel candidate for future pharmaceutical manufacturing. Since the first drug product (Spritam®) has been approved for commercialization by the Food and Drug Administration (FDA), there has been an enormous opportunity for printing custom drugs using 3DP. Many 3DP methods have been documented for pharmaceutical applications in the literature. However, selective laser sintering (SLS) printing remains the least studied for pharmaceutical applications. There are many advantages and challenges in adopting an SLS method to fabricate personalized medicines, such as accurate, cheaper, and simpler ways to configure dosing for certain patient groups. In this study, we systematically reviewed all available literature investigating the technique of personalized printlets using SLS printing, and further discussed the method used in its process. A systematic searching strategy was performed in Scopus, PubMed, and Google Scholar databases using predetermined search strings. Of the 122 articles, only eight articles completely met the inclusion criteria, and they were subsequently used for data synthesis. The results showed that the printing process, spectrophotometry analysis, thermal analysis, X-ray powder diffraction and characterization of the printlet were the vital parameters in the printing method, leading to potential pharmaceutical applications in personalized medicine.

Structural and optical analysis of film Sn6.3Pb93.7 prepared from coarse Sn63Pb37

Refining the coarse Sn63Pb37 soldering alloy paste reduces environmental pollution with reusable lead (Pb) content and the cost of raw material of Sn–Pb composite used in industrial, solar, optoelectronic applications. Better solvent suitable for the Refinement process(RP) of coarse Sn63Pb37 with analysis of multi/single phase of XRD (X-ray diffraction pattern) pattern for increased lead(Pb) weight has investigated in this work based on value of χ2 (Chi square). Average crystalline size(Davg) of coarse Sn63Pb37refined with ethanol solution is 0.151 μm.Film Sn6.3Pb93.7 is prepared from the Sn19.6Pb80.4 (i.e. RP − SnxPby(ethanol)) alloy powder using FCAM (Fused-coating based additive manufacturing) method followed by laser beam layering method of SLS(selective laser sintering). Prepared film has porosity of 46.48% and it is observed that decreased porosity decreased the Sn content and increased the Pb.Sn19.6Pb80.4sample, film Sn6.3Pb93.7 optical parameters in the UV–vis region of 400 nm–800nm are evaluated from the optical absorbance measurements. Using GPVDM(general purpose photovoltaic device model), the film Sn6.3Pb93.7 photon density, absorbed photon density, and generation rate are decreased from surface to bottom of film thickness with AM 1.5G optical simulation.

Boosted Mechanical Piezoelectric Energy Harvesting of Polyvinylidene Fluoride/Barium Titanate Composite Porous Foam Based on Three-Dimensional Printing and Foaming Technology.

The popularity of intelligent and green electronic devices means that the use of renewable mechanical energy has gradually become an inevitable choice for social development. However, it is difficult for the existing energy harvesters to meet the requirement for efficient collection of discrete mechanical energy due to the limitation of traditional two-dimensional (2D) film deformation. In this research, a green and convenient supercritical carbon dioxide foaming (Sc-CO2)-assisted selective laser sintering method was developed, and piezoelectric energy harvesters with a 3D porous structure of polyvinylidene fluoride (PVDF)/barium titanate (BaTiO3) were successfully constructed. The 3D structure combined with the porous structure made full use of the normal space, amplified the stress–strain effect, and improved the piezoelectric output capability. Under the synergistic effect of BaTiO3, the foams exhibited high output with an output voltage of 20.9 V and a current density of 0.371 nA/mm2, which exceeded most of the known PVDF/BaTiO3 energy harvesters, and the prepared piezoelectric energy harvester could directly light up 11 green light-emitting diodes and charge a 1 μF commercial capacitor to 4.98 V within 180 s. This work emphasizes the key role of 3D printing and Sc-CO2 foaming in fabricating 3D piezoelectric energy harvesters.

Effects of copper fillers on mechanical and electrical properties of selective laser sintered PA 12-Cu composites

ABSTRACT Selective Laser Sintering (SLS) is a widely used additive manufacturing (AM) technique for creating 3D geometries by adding materials in layers. Although neat polymer is mainly used in powder forms for production, organic or inorganic fillers can be added to produce polymer composites by SLS method. In this study, Polyamide 12 (PA 12) matrix composite parts filled with two different copper particles, dendritic and spherical shaped, were produced, and their mechanical, structural and electrical properties were investigated. The present study outlined that by increasing incident energy densities during sample fabrication, changes in mechanical and electrical characteristics were examined. The findings were analysed in terms of filler type and energy input, which were discovered to have a slight change in the bending behaviour of SLS components. Furthermore, the impact strength was shown to increase constantly with increasing energy density. Furthermore, whereas the electrical conductivity of spherical Cu-filled parts rose considerably, no significant change was seen in dendritic-shaped Cu-filled parts.

Rapid casting technology based on selective laser sintering

Selective laser sintering (SLS), as a kind of additive manufacturing technology, which uses a laser beam to scan and heat powder material layer by layer to form parts (models), is widely used in the field of casting, mainly for preparing casting coated sand cores, investment casting patterns, etc. The SLS technique facilitates rapid casting and shortens the casting production periods by eliminating mold preparation. In this study, we reached conclusions for the basic principles and characteristics of SLS methods, and focused on the research status, key technology and development trend of SLS in the fields of forming coated sand-casting molds and investment casting patterns.

ПЕРСПЕКТИВЫ ИЗГОТОВЛЕНИЯ КАРКАСОВ МЕТАЛЛОКЕРАМИЧЕСКИХ КОНСТРУКЦИЙ ЗУБНЫХ ПРОТЕЗОВ МЕТОДОМ СЕЛЕКТИВНОГО ЛАЗЕРНОГО СПЕКАНИЯ

The article presents the results of evaluating the prototyping of metal-ceramic structures made by casting and selective laser sintering. To achieve this goal, 27 patients with fabricated metal-ceramic crowns and bridgeworks were examined. Two study groups were created. The first group included 14 patients for whom dental prosthesis frameworks were made by casting. The second group consisted of 13 people, for whom the frames of dentures were made by the method of selective laser sintering. The analysis of clinical effectiveness was carried out according to the following criteria: 1- precision of the felling of prosthesis frame to solid tissues of abutment teeth; 2- the condition of the marginal periodontium; 3- the integrity of the ceramic cladding. The results of the study showed that the precision to solid tooth tissues of metal-ceramic dental prostheses made by laser selective sintering is higher than of frames made by casting. In accordance to the second criteria the best results were also shown by the participants of the second group. No chipping of the ceramic veneer from the metal-ceramic denture frameworks made by laser selective sintering was found. Thus, dentures which frameworks are made by the method of selective laser sintering are characterized by a higher objective assessment of their precision to the solid tissues of the abutment teeth. Lesions of the marginal periodontium both inflammatory and dystrophic were less in the participants of the second group. The frequency of defects in the coating of metal-ceramic dentures was significantly lower in the case of fabrication frameworks by laser selective sintering.

Energy absorption properties of macro triclinic lattice structures with twin boundaries inspired by microstructure of feldspar twinning crystals

Inspired by the microstructure of the triclinic crystal material, in this work we designed triclinic lattice structures (TC) with twin boundaries for energy absorption application. The deformation mode and energy absorption capacity of TCs under the quasi-static compression are investigated by finite element method, which is validated by the experiments on the TC specimen additively manufactured by the selective laser sintering (SLS) method. The TC design is further extended to the triclinic body-centered cubic lattice structures (TBCC). The results indicate that introducing twin boundaries into the lattice structure can control the deformation mode and thus improve the energy absorption performance. The energy absorption increases with the number of twin boundaries in both TCs and TBCCs. In addition, the plateau stress and the equivalent grain size of the proposed structures are found to also obey the Hall-Petch relationship that is prevalent in the polycrystal materials. This work verifies the feasibility of the approach of designing novel lattice structures by mimicking the material microstructures.