Laser Sintering Research Articles

3D and 4D Technology for Pharmaceutical Drug Delivery: A Detailed Insight

3D Printing, sometimes referred to as additive manufacturing, has made the concept of personalized medicine a reality. The primary objective of 3D and 4D printing is to produce intricate, customized pharmaceuticals at a reasonable cost. With improvements in materials, resolution, and speed, 3D printing technology is quickly developing. It includes faster construction, cost efficiency through reduced waste, design flexibility for complex structures, and sustainability through optimized material usage. An extensive literature survey was done on 3D and 4D printing of pharmaceuticals using PubMed, Elsevier, ScienceDirect, and Springer. The results were then filtered based on the titles, abstracts, and accessibility of the complete texts. The search engine Google Scholar was accessed for literature data mining. From the data mining, it was found that from the year 2009 to 2024 the number of research publications surged more than 200 times on the current topic. Even though 3-D and 4-D printing technologies have advanced significantly in a short amount of time, the most often used ones are still stereolithography, nozzle-based deposition, inkjet, and selective laser sintering. Their use has been modified for the production of nanoparticles, polypills, tablets, and implants, etc. Pharma's aspirations for tailored medications are being revolutionized by 3D printing, but cost, flexibility, and bioequivalence still need to be investigated. The present review offers a thorough analysis of various 3D and 4D printing methods and emphasizes the major advantages and disadvantages and major key challenges of 3D and 4D printing related to pharmaceuticals. Compared to 3D Printing, 4D printing offers better quality, efficacy, and functionality.

A study on the machinability of DMLS In718 alloy using an electro-spark machining process

ABSTRACT The direct metal laser sintering process is used to develop the nickel base superalloy DMLS In718 for the experimentation. The DMLS In718 alloy is evaluated to ensure the metallurgical qualities and mechanical properties. Microstructure of the DMLS In718 alloy is anisotropic in nature and the hatch bands are clear to infer. The hardness of the DMLS In718 is 275 Hv which equivalent to the commercially available inconel718 material. the mechanical strength and density of the DMLS In718 alloy is justifiable to the commercial material. The machining studies are performed with electro spark erosion process to report on surface quality, kerf taper and material removal rate. the minimum pulse on time has produced a fine surface quality compared to the maximum process condition. The surface topography in terms of oxide scale and recast layers are identified during to inefficient process conditions. This paper was an opportunity to deliberate the machining quality of the wire electro spark process.

3D-Printed Shape Memory and Piezoelectric Bifunctional Thermoplastic Polyurethane/Polyvinylidene Fluoride Porous Composite Scaffold for Bone Regeneration.

Physical stimulations such as mechanical and electric stimulation can continuously work on bone defect locations to maintain and enhance cell activity, and it has become a hotspot for research in the field of bone repair. Herein, bifunctional porous composite scaffolds with shape memory and piezoelectric functions were fabricated using thermoplastic polyurethane (TPU) and poly(vinylidene fluoride) through triply periodic minimal surfaces design and selective laser sintering technology. Thereinto, the shape fixity ratio and recovery ratio of the composite scaffold reached 98.6% and 81.2%, respectively, showing excellent shape memory functions. More importantly, its piezoelectric coefficient (d33 = 2.47 pC/N) is close to the piezoelectric constant of bone tissue (d33 = 0.7-2.3 pC/N), and the voltage released during the compression process can reach 0.5 V. Furthermore, cyclic compression experiments showed that the strength of composite scaffold was up to 8.3 times compared with the TPU scaffold. Besides, the composite scaffold showed excellent cytocompatibility. In conclusion, the composite scaffold is expected to continuously generate mechanical and electric stimulation due to shape memory and piezoelectric function, respectively, which provide an effective strategy for bone repair.

Laser Sintering by Spot and Linear Optics for Inkjet-Printed Thin-Film Conductive Silver Patterns with the Focus on Ink-Sets and Process Parameters

The implementation of the laser sintering for inkjet-printed nanoparticles and metal organic decomposition (MOD) inks on a flexible polymeric film has been analyzed in detail. A novel approach by implementing, next to a commonly 3.2 mm diameter spot laser optic, a line laser optic with a laser beam area of 2 mm × 80 mm, demonstrates the high potential of selective laser sintering to proceed towards a fast and efficient sintering methodology in printed electronics. In this work, a multiplicity of laser parameters, primary the laser speed and the laser power, have been altered systematically to identify an optimal process window for each ink and to convert the dried and non-conductive patterns into conductive and functional silver structures. For each ink, as well as for the two laser optics, a suitable laser parameter set has been found, where a conductivity without any damage to the substrate or silver layer could be achieved. In doing so, the margin of the laser speed for both optics is ranging in between 50 mm/s and 100 mm/s, which is compatible with common inkjet printing speeds and facilitates an in-line laser sintering approach. Considering the laser power, the typical parameter range for the spot laser lays in between 10 W and 50 W, whereas for the line optics the full laser power of 200 W had to be applied. One of the nanoparticle silver inks exhibits, especially for the line laser optic, a conductivity of up to 2.22 × 107 S‧m−1, corresponding to 36% of bulk silver within a few seconds of sintering duration. Both laser sintering approaches together present a remarkable facility to use the laser either as a digital tool for sintering of defined areas by means of a spot beam or to efficiently sinter larger areas by means of a line beam. With this, the utilization of a laser sintering methodology was successfully validated as a promising approach for converting a variety of inkjet-printed silver patterns on a flexible polymeric substrate into functionalized conductive silver layers for` applications in the field of printed electronics.

Advancing self‐lubricating technology: Selective laser sintering molding assisted development of copper‐based polytetrafluoroethylene /graphite composites

AbstractThis study introduces an innovative technique for the fabrication of copper‐based polytetrafluoroethylene (PTFE)/graphite self‐lubricating composites. By harnessing the exceptional capabilities of selective laser sintering (SLS), we efficiently create three‐dimensional, continuous, and porous graphite preforms. Following this, the composite is formed through a combination of electroplating and vacuum extrusion methods. Subsequently, PTFE was vacuum impregnated into the microporous structure of the graphite preforms, and the composites were obtained through freeze‐drying, plasticizing, and machining processes. The resulting copper‐based PTFE/graphite self‐lubricating composites exhibit an exceptional blend of properties. Notably, there is a significant reduction in the average coefficient of friction, dropping from 0.14 to 0.02, and a marked decrease in the wear rate, from 1.358 × 10−5 to 1.109 × 10−5 mm3/N·m, as compared to graphite as a standalone lubricant. This represents a substantial improvement in performance, underscoring the effectiveness of the proposed fabrication method.Highlights The porous graphite with controllable shape distribution was prepared. Surface copper plating improves surface bonding. Controllable copper matrix composites with double lubricant were prepared. The average friction coefficient is as low as 0.02.

Study on the laser sintering process of veined red snail/polylactic acid composite powder

Drawing on the composition of shells and the microstructure of cross-laminated sheets, laser sintering technology was used to prepare laser-sintered fabrications of veined red snail powder as an inorganic material and polylactic acid (PLA) as an organic material. The process was optimized using the response surface method based on one-way experiments by adding veined red snail powder. At a 13.27 W laser power, 1.2 m/s scanning rate, 0.17 mm scanning spacing, and 0.23 mm delamination thickness, the bending strength of the veined red conch powder/PLA composite powder parts reached 8.53 ± 0.15 MPa, with an error of only 1.7% from the model’s predicted value. Under these process conditions, the characterization of laser-sintered parts with 0, 5, 10, 15, 20, and 25 wt% veined red snail powder revealed that parts with 15 wt% exhibited optimal mechanical properties, showing a 155.9% improvement over pure PLA parts.

Optimizing hydraulic systems through connection reduction: Mitigating leakage risks

The article discusses the application of the additive manufacturing method DMLS (Direct Metal Laser Sintering), using AlSi10Mg powder for consolidating components used in hydraulic systems to enhance their reliability and reduce the risks associated with potential leaks. Strength tests were conducted, and the difference between a traditional joint and a printed filter connection head was presented. The dimensions and weight of both components are shown in a table. The strength parameters of the printed components are comparable to those manufactured using traditional methods. The results of these tests demonstrate that the produced elements fulfill their function while simultaneously reducing the number of parts in the system and minimizing the areas that require precise sealing preparations. The obtained results provide a solid foundation for further research on the application of this technology in hydraulic systems.

Crashworthiness study of polyamide bi-tubular thin-walled tubes using hybrid lattice filling

Thin-Walled Tubes (TWT) are widely used as crashworthiness elements to absorb and dissipate kinetic energy during collision through plastic deformation. Various design strategies, including nested tubes, triggers, and filling with lattices, are commonly used to enhance the crashworthiness of TWT. Additive Manufacturing (AM) offers unique opportunities to produce complex lattice-filled TWT with higher precision, but challenges persist in the design and fabrication of bi-tubular TWT to enhance crashworthiness. The aim of this study is to propose an approach for hybrid lattice filling in bi-tubular structures. In the preliminary phase, the parametric study was conducted to understand the influence of tube cross-section geometry, thickness, and trigger hole diameter on the crashworthiness of empty TWT using Taguchi’s L9 orthogonal array. Empty TWTs were fabricated using Selective Laser Sintering (SLS) with PA12 material and compressed uni-axially at 8 mm/min speed. In the second phase, bi-tubular TWT was filled with three different unit cells such as Cube, Kelvin, and Octet Truss (OT) having 30% relative density. In the lattice filling approach, two different strategies were followed such as uniform and hybrid lattice filling. Designed TWTs were fabricated and tested under uni-axial compression at two different speeds such as 8 mm/min and 8 mm/sec. Based on the results of the preliminary study, it has been observed that cross-section geometry and tube thickness significantly enhance SEA through an increase in the stiffness and number of folding. With the help of the Signal to Noise (S/N) ratio graph, appropriate levels were selected as input for the hybrid lattice-filling approach. The results of the second phase revealed that hybrid lattice filling significantly enhances the deformation modes, energy absorption, and crashworthiness properties of TWTs. Hybrid lattice-filled TWT offers better Specific Energy Absorption (SEA) as 18.32 kJ/kg at 8 mm/sec compression speed, which is 113.9% higher than empty and 42.8% higher than uniform lattice-filled TWT. This work demonstrated that adopting the hybrid lattice-filling approach is one of the potential ways to enhance the crashworthiness of protective equipment such as crash boxes and frames.

Analytical and numerical analysis of heat transfer and temperature distribution in laser sintering method

Analytical and numerical analysis of heat transfer and temperature distribution in laser sintering method

A critical assessment of the onset strain of densification in the evaluation of energy absorption for additively manufactured cellular materials

Densification strain is an essential parameter in the characterization of energy absorption of additively manufactured cellular structures. In addition to its own merits as a metric that indicates usable stroke length for energy absorbers, it is central to the computation of energy absorbed by the structure. However, at least four different approaches have been used in the literature, each with its own limitations. In this work, a critical review of these approaches is first presented. While the maximum efficiency approach has been demonstrated to be optimal for cellular foams, this work shows how, for some additively manufactured cellular materials, it can fail to estimate densification strain accurately due to its sensitivity to instantaneous stress values in the plateau region. An alternative method is proposed in this work that leverages peak stress instead to determine the onset strain of densification and is shown to be consistently accurate across a range of cellular materials. The method is validated with the results from an experimental study of energy absorption in six different types of cellular structures across three relative densities, with identical geometries fabricated in two different base materials and processes: AlSi10Mg with Laser Powder Bed Fusion, and Nylon-12 with Selective Laser Sintering.

Structural integrity of polymers processed by additive manufacturing techniques using residual strength diagrams

Motivated by the increasingly important role that polymers have in structural applications, this study aims to analyse the structural integrity of polymers through residual strength diagrams. The polymers analysed have been thermoplastics, Polylactic acid (PLA), Polyethylene terephthalate glycol-modified (PET-G) and Polyamide 12 (PA-12), as well as a thermosetting resin, processed through different additive manufacturing techniques: Fused Deposition Modelling (FDM) in the case of PLA, PET-G, Selective Laser Sintering (SLS) for PA-12 and Digital Light Processing (DLP) for the thermosetting resin. In addition, PA-12 manufactured by injection moulding was also included in this study. To obtain the residual strength diagrams, mechanical tests have been carried out on smooth specimens and on specimens with cracks of different lengths. From the analysis of the results, a prediction has been obtained by fitting a semi-empirical model that describes the structural integrity in the areas of microstructurally short cracks, long cracks and physically short cracks.

Illumination Correction and Enhancement Algorithm for Defective Powder Spreading Images in Selective Laser Sintering

Abstract Based on the uneven illumination distribution and low defect contrast in the powder spreading images acquired during the selective laser sintering manufacturing process, which affects subsequent defect detection, an adaptive nonlinear illumination correction and enhancement algorithm is proposed. Local illumination correction is performed using gray valueitting curves and is combined with global gamma correction to improve correction capability in overly dark areas. A nonlinear enhancement function is constructed to boost the contrast of the image’s illumination component. Finally, a gradient-based L0 norm minimization algorithm is used to smooth non-defect areas. Experimental results show that the proposed algorithm signi icantly improves correction and enhancement, outperforming comparison algorithms overall. Compared to the original images, the coef icient of variation decreases by an average of 0.179, and the standard deviation increases by an average of 26.7%, demonstrating the effectiveness of the proposed algorithm.

The effect of laser beam shaping on the structural and XEOL properties of laser-sintered LiBaPO4:Eu ceramics

In this work, we investigated the impact of laser beam shaping during laser sintering on the structural and XEOL properties of Eu-doped LiBaPO4 ceramic phosphors synthesized via the sol-gel method with PVA. Structural and optical properties were characterized using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Absorption Near Edge Structure (XANES), X-ray fluorescence (XRF), and X-ray Excited Optical Luminescence (XEOL). XRD analysis revealed a primary trigonal phase (LiBaPO4, space group P31c) alongside a minor Ba3(PO4)2 phase. SEM images indicated a uniform grain size distribution, while XEOL spectra showed emission peaks corresponding to Eu3+ and Eu2+ ions, as well as defects from laser ablation. The Eu2+/Eu3ratio varied from the center to the edge of the ceramic body. Additionally, the laser beam shape contributed to a more homogeneous distribution of Eu ions in the center compared to the edge of the ceramic body.

Assessment, analysis and optimization for high temperature sliding wear process parameter with additive built nickel base superalloy

Abstract Superalloys are highly demanding alloy for high temperature application. The conventional production process and metallurgical sustainability of the superalloy against the applications is the preamble of the existing research. Based on the review it is clear to say that the development of nickel base superalloy with advanced technique without compensating the quality is open for research. The nickel base superalloy is developed through additive manufacturing process following a metal laser sintering technique. The developed alloy is used to perform high temperature sliding wear analysis with the different input process conditions. Applied load, sliding duration and the working temperature are the defined process environment for the investigation. The process conditions are designed with twenty-seven set of experimental trials for statistical analysis and process assessment. The responses on surface roughness and the material loss with respect to the input process parameters are technically assessed and justifications made with the electron microscopic images. The surface topography has influenced due to applied load and the sliding duration. Applied load has influenced the contact area prone with severe wear and the ridges are notice from the microscopic analysis. The statistical analysis has proved that the influence of temperature is less and negotiable compared to the load and time factor. From the optimization process, the optimal parameter for the experimental design is 10 N, 100 °C and 30 min is the ultimate condition to produce best results from the high temperature sliding wear analysis.

INNOVATIVE APPROACH TO ENSURING THE QUALITY OF GAS TURBINE ENGINE PARTS PRODUCED BY SELECTIVE LASER SINTERING FOR UAV

The research objects are gas turbine engines parts, manufactured using an innovative method of additive manufacturing – selective laser sintering. The main problem solved in this work is the low quality of the surface layer and the residual porosity of the parts obtained by this method, which significantly limits their operational characteristics and durability. As a result of the experimental studies, rational operating parameters of diamond smoothing were established. This allowed to significantly improve the surface quality and increase the operational characteristics of parts made of heat-resistant alloys INCONEL 718 and an intermetallic alloy based on titanium aluminide OX45-3ODS. The effectiveness of diamond smoothing is explained by local plastic deformation and compaction of the surface layer of parts under the influence of high contact pressures and temperatures. This leads to a significant reduction in surface roughness, an increase in the surface hardness due to strain hardening and a significant reduction in the size and number of residual pores. A characteristic feature of the obtained results is the ability to control the quality parameters of the surface layer by varying the diamond smoothing operating parameters – smoothing force, feed, radius, and geometry of the smoother's working part. The established regularities of the smoothing operating parameters have an impact on the quality characteristics of the surface. This information can be utilized in the development of highly efficient technological processes for the production and restoration of gas turbine engines, critical components of unmanned aerial vehicles, obtained through selective laser sintering. Implementing the elaborated technological recommendations will permit broadening the range of goods produced by additive manufacturing and enhancing their capacity and dependability during operation under conditions of cyclical loads and extreme temperatures.

Dimensional reliability in CAD/CAM production of complete denture bases: A comparative study of milling and various 3D printing technologies.

This study aims to assess the dimensional accuracy of complete denture bases fabricated from different CAD/CAM technologies and a conventional method, including milling (CNC), PolyJet (PJ), laser sintering (SLS), digital light processing (DLP), and injection molding (IM). It also examines the influence of the removal of technology-specific connectors or support structures when present. Denture base surfaces were digitized using a laboratory scanner, and virtual measurement points were calculated with tetrahedral reference geometries. Defined distances were measured in all spatial directions and compared to design data (p<0.05), revealing significant differences in sagittal (p=0.004), transversal (p<0.001), and vertical (p<0.001) dimensions. Connector removal had no significant impact for CNC but significantly affected DLP. All technologies yielded clinically acceptable results, with CNC milling demonstrating the best overall outcome.

Enhancing experiential learning through virtual reality: System design and a case study in additive manufacturing

AbstractThe recent advancement in additive manufacturing (AM) leads to an extensive need for an industrial workforce in the near future. Workforce training in AM requires expensive capital investment for installing and maintaining this technology and proper knowledge about potential safety hazards. Traditional classroom settings often fail to bridge the critical gap between textbook learning and practical applications. Virtual reality (VR) training can simulate real‐world scenarios in a safe and controlled environment and improve student involvement to foster practical learning. In this paper, a virtual training platform for 3D printing has been developed and studied to improve AM education. The developed environment contains a selective laser sintering printer, a preparation station with necessary supplies, a control panel for process planning, and a post‐processing station. This platform provides students with excellent learning opportunities to gain hands‐on experiences and critical engineering skills on operating process parameters and safety measures. Undergraduate students majoring in industrial engineering were exposed to this learning approach to enhance their engagement and cognitive processing skills. Students' attentions were measured using eye metrics (fixation duration and preference index), and their exposure experiences were collected through the simulation sickness questionnaire, presence questionnaire, and system usability scale. Pre‐ and post‐VR training questionnaires and performance metrics (task completion time and accuracy) evaluated students' learning outcomes. Results provide valuable insights into students' attention, performance, and satisfaction with virtual training environments. Users' gaze behavior and subjective responses revealed many challenges that will help future researchers develop assistive instructions within this virtual educational platform.

Thermomechanical Assessment of Recovered PA12 Powders with Basalt Filler for Automotive Components

Additive manufacturing processes allow for precise and efficient production, but it is estimated that one-third of the materials used results in waste. Further improvement in a sustainable perspective could come from the ability to manage these scraps and from the exploration of different routes for recovery and reuse. The Selective Laser Sintering process is particularly sensitive to this issue due to the waste ratio which can reach a very high quantity of not-sintered virgin powders. In this research study, recovered PA12 powders, preliminarily characterized through thermal and mechanical analysis, were mixed with 15% basalt powder to improve their aspect and thermomechanical resistance. The influence of basalt powder (BP) on mechanical properties as well as on the thermal stability of polyamide12 (PA12) powder composites was investigated. A study conducted on mechanical properties showed that polymeric composites’ stiffness and hardness were influenced by adding filler, thus improving mechanical parameters. On the other hand, the application of thermogravimetric analysis allowed us to determine the composite’s thermal stability. The objective is to obtain a recovered fully biobased material that could be used to substitute the petroleum-derived polymeric ones currently employed in the production of interiors and shells in the automotive sector.

Laser Metal Printing from Nanoparticles Prepared by a Gas Aggregation Source.

This study demonstrates the use of nanoparticles prepared by a gas aggregation source for fabricating structures by combining laser sintering and ablation. At first, the morphology and optical properties of prepared nanoparticle coatings were characterized. Then, the response of coatings to laser irradiation at different powers or exposure times was studied by in situ time-of-flight mass spectrometry, followed by scanning electron microscopy measurements of the resulting structures. By comparing the numbers of detected Ag ions, that were ablated and desorbed, with changes in morphology after irradiation, the optimum conditions for laser sintering and ablation of Ag nanoparticle coatings were found. As a proof of concept we fabricated micromirrors from sintered metal, microwires from both sintered metal and interconnected nanoparticles, and arbitrary metallic bulky or nanoparticle patterns. Vacuum compatibility and the possibility of fabrication of both metallic and nanoparticle structures in one step predetermines applications of developed method in electronics or sensing.

Impact of Glow-Discharge Nitriding Technology on the Properties of 3D-Printed Grade 2 Titanium Alloy.

This study presents a comparative analysis of the corrosion resistance of nitrided layers on conventional Grade 2 titanium alloy and those produced by direct metal laser sintering (DMLS). Low-temperature glow-discharge nitriding of the tested materials was carried out using conventional glow-discharge nitriding (so-called nitriding at the cathode potential-TiN/CP) and with the use of an "active screen" (nitriding at the plasma potential-TiN/PP). The TiN + Ti2N + Ti(N) layers were characterized by their microstructure, nanohardness profile distribution, surface topography, and corrosion resistance. The reduction in the cathodic sputtering phenomenon in the process using the active screen allowed the creation of surface layers that retained the topography of the base material. The parameters of the glow-discharge treatment led to grain growth in the printed substrates. This did not adversely affect corrosion resistance. The corrosion resistance of nitrided layers on the printed titanium alloy is only slightly lower than that of layers on the conventional Grade 2 alloy. Iron precipitates at grain boundaries facilitate increased nitrogen diffusion, resulting in reduced nitrogen concentration in the surface layer, slight changes in corrosion potential values, and increased nitrogen concentration in the Ti(N) diffusion layer.