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Spectroscopic monitoring of laser blown powder directed energy deposition of Alloy 718
摘要： Experimental explorations of a spectrometer system used for in-process monitoring of the laser blown powder directed energy deposition of Alloy 718 is presented. Additive manufacturing of metals using this laser process experiences repeated heating and cooling cycles which will influence the final microstructure and chemical composition at every given point in the built. The spectrometer system disclosed, under certain process conditions, spectral lines that indicate vaporisation of chromium. Post process scanning electron microscope energy dispersive spectroscopy analysis of the deposited beads confirmed a reduction of chromium. Since the chromium concentration in Alloy 718 is correlated to corrosion resistance, this result encourages to further investigations including corrosion tests.
关键词： additive manufacturing,laser blown powder directed energy deposition,spectroscopic system,in-process monitoring
更新于2025-11-21 11:01:37
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Measuring bulk density variations in a moving powder bed via terahertz in-line sensing
摘要： Monitoring the relative density of static or moving powder inside a process line is essential for manufacturing high-quality products. The aim of this study was to predict density variations in a moving powder bed using terahertz reflection technology. We systematically investigated three grades (varying true density and particle size) of two materials: lactose and silicified microcrystalline cellulose (SMCC). These six powders specifically differ in their compressibility, which can be applied to assess the sensitivity and applicability of our method. The powders were filled into a round container, and terahertz reflection measurements were acquired continuously during the container's rotation. The setup allowed to adjust the relative density by compacting the powders into specific powder bed heights. Each powder was compacted to various relative densities (compression pressures up to 100 kPa). We calculated the surface refractive index based on the in-line terahertz measurements acquired during rotation, which has a linear dependence on the relative density of the powder. This was confirmed by correlating the refractive index values with the theoretical relative densities based on the bulk and true densities of the powder. The coefficient of determination (R2) was larger than 0.962 (Lactohale 100) for all six powders, with the highest coefficients for Lactohale 220 (R2 = 0.996) and SMCC 50 LD (R2 = 0.995). The results suggest that the proposed method can resolve relative densities averaged across the powder bed that are as small as 0.3% (Lactohale 100). The high acquisition rate of the terahertz system (15 Hz) made it possible to determine the powder density in 230 positions uniformly distributed throughout the container, facilitating the investigation of the relative density uniformity in the container as a function of the powder bed height. It was observed that SMCC powders undergo a smaller change in the relative density variations upon compaction than the lactose powders. Moreover, the relative density maps clearly indicate local density differences in the powder bed for all powders. The relative density variations that were introduced by packing of the container prevailed throughout the compaction process for all samples with the exception of Lactohale 220. The presented approach allows a precise resolution of the spatial distribution of relative density, which facilitates an in-depth analysis of powder behavior upon compaction.
关键词： Powder density,Process monitoring,Process analyzer,Terahertz in-line sensing,Capsule filling
更新于2025-09-23 15:23:52
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Simultaneous quantitative analysis of indomethacin and benzoic acid in gel using ultra-violet-visible spectrophotometry and chemometrics
摘要： BACKGROUND: In order to manufacture pharmaceutical products, real-time monitoring in the manufacturing process is necessary, but large equipment cost is required to achieve it. OBJECTIVE: The aim of this research is to use ultra-violet-visible spectroscopy along with chemometrics procedure to simultaneously quantitative analysis of indomethacin (IMC) and benzoic acid (BA) in the gel during pharmaceutical manufacturing process. METHODS: The gel preparations were contained of 0.1–1.5% IMC, 0.015–0.225% BA, 2% carbopol? 941 and 95% ethanol solution. The calibration models were constructed using the partial least square regression (PLS). RESULTS: The relationships of the measured and predicted concentrations for both IMC and BA had linear plots. The developed PLS calibration models were used to monitor the IMC and BA concentrations during mixing of the gels by the planetary centrifugal and conventional mixers, respectively. IMC and BA were gradually dispersed, dissolved and completely homogeneous within 30 min by the centrifugal mixer. In contrast, IMC and BA were slowly dispersed, dissolved and completely homogeneous at more than 60 min by the conventional mixer. CONCLUSIONS: The ultra-violet-visible spectrophotometric method couples with multivariate chemometric techniques for quantitative data analysis were successfully applied for the simultaneous determination of major component IMC and trace component BA in the gel.
关键词： benzoic acid,indomethacin,partial least square regression,Ultra-violet-visible spectroscopy,process analysis technology,process monitoring
更新于2025-09-23 15:22:29
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Analysis of Optical Plasma Monitoring in Plasma-Enhanced Atomic Layer Deposition Process of Al <sub/>2</sub> O <sub/>3</sub>
摘要： A noninvasive, optical plasma monitoring method in plasma-enhanced atomic layer deposition (PEALD) process for nanoscale water vapor barrier film is presented. Any equipment malfunction, as well as a deviation in the condition of individual components can easily jeopardize the process result. Al2O3 deposition process was employed in this research as a test vehicle, and high-speed optical plasma monitoring was demonstrated. It is shown that optical plasma monitoring is useful for not only measuring plasma pulses in real time, but also for the detection of any variation in plasma condition which enables inferring plasma dynamics for advanced process control in nanoscale thin film deposition process.
关键词： PEALD,Process Monitoring,Plasma Diagnostics,Fault Detection
更新于2025-09-23 15:22:29
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Correlating in-situ process monitoring data with the reduction in load bearing capacity of selective laser melted Tia??6Ala??4V porous biomaterials
摘要： Selective Laser Melting allows for the creation of intricate porous structures, that possess favourable biological properties. These structures are known as porous biomaterials. The focus of this paper is to evaluate the use of an in-line photodiode based process monitoring system, for the monitoring of the operational behaviour of the laser, and to correlate this with the resultant parts mechanical performance. In this study the production scale Renishaw 500M was used to produce porous structures, using Ti–6Al–4V feedstock powder. During the process, a co-axial process monitoring system was utilised to generate data relating to both the meltpool and the operational behaviour of the laser. An advanced scanning technique was used to produce the structures, whereby the laser parameters determine the strut dimensions. In this study, the laser input energy was reduced by 33%, 66% and 100%, at specific layers within the structures. Computer Tomography and Scanning Electron Microscopy was utilised to characterise the affected struts within the structures, while quasi-static compression testing was used to determine the structure’s mechanical properties. It was demonstrated that as the level of input energy decreased and the number of affected layers increased, a corresponding decrease in the load bearing capacity of the structures occurred. With the structures experiencing a significant loss in strength also exhibiting a change in the failure mode during compression testing. Data generated during the processing of such structures was compared to the data generated during the processing of control structures, with the difference between the two been calculated on a layer-by-layer basis. A clear correlation was demonstrated between the total level of deviation between the two signal sets and a reduction in the load bearing capacity of the structures. This indicates that by comparing build data to a benchmark data set, valuable information relating to the structural integrity of the porous structures can be obtained.
关键词： Porous structures,Selective laser melting,Process monitoring
更新于2025-09-23 15:21:01
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Selective Laser Sintering 3D Printing a?? An Overview of the Technology and Pharmaceutical Applications
摘要： Food and Drug Administration (FDA) has approved a drug product (Spritam?) and many medical devices manufactured by 3-dimensional printing (3DP) processes for human use. There is immense potential to print personalized medicines using 3DP. Many 3DP methods have been reported in the literature for pharmaceutical applications. However, selective laser sintering (SLS) printing has remained least explored for pharmaceutical applications. There are many advantages and challenges in adopting a SLS method for fabrication of personalized medicines. Solvent free nature, availability of FDA approved thermoplastic polymer/excipients (currently used in hot melt-extrusion process), minimal/no post-processing step, etc. are some of the advantages of the SLS printing process. Major challenges of the technology are requirement of at least one thermoplastic component in the formulation and thermal stability of drug and excipients. This review provides an overview of the SLS printing method, excipient requirements, process monitoring, quality defects, regulatory aspects and potential pharmaceutical applications.
关键词： in-process monitoring,selective laser sintering,personalized medication,3D printing,quality defects,pharmaceuticals
更新于2025-09-23 15:21:01
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Research on epoxy resin curing monitoring using laser ultrasonic
摘要： Adhesive bonding is widely used in the structural assembly of aircraft, and assessing the curing state of the adhesive is important to ensure the safe operation of the assembly. In this paper, the curing process of epoxy resin is monitored by laser ultrasonics. The propagation of ultrasonic waves in a composite structure is discussed, and the curing of epoxy resin and its influence on ultrasonic characteristics are studied. In the fast-drying epoxy resin, the molecular cross-linking rate is fast, the difference of acoustic impedance between the epoxy resin and aluminum gradually decreases, so the transmission coefficient becomes larger and the reflection coefficient decreases. The calculation of absorption attenuation and dispersion should take this change into account. The relationship between amplitude and reflection coefficient is established by far-field ultrasound. The difference in molecular mobility causes the relaxation process, which results in absorption and dispersion of the ultrasonic waves. Making use of the broadband characteristic of laser ultrasonics, the transmission waves are analyzed. As the epoxy resin changes from liquid to solid, the relaxation time is gradually shortened, and the center frequency of the transmitted wave is gradually increased, the absorption attenuation is approximately linear with frequency. The results show that the curing process has a significant effect on ultrasonic characteristics, and laser ultrasonics could be used as an online monitoring method.
关键词： Adhesion,Interface,Non-destructive testing,Process monitoring
更新于2025-09-23 15:21:01
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Development and Evaluation of an In-line and On-line Monitoring System for Granule Size Distributions in Continuous Roll Compaction/Dry Granulation Based on Laser Diffraction
摘要： Purpose Roll compaction/dry granulation is established in manufacturing of solid oral dosage forms and, within the context of continuous manufacturing, it has sparked interest as material is fed, processed, and ejected continuously while also providing large possible throughputs. However, this amount of material has to be adequately controlled in real time to assure quality. Methods This research aimed at monitoring the critical quality attribute granule size distribution in continuous roll compaction/dry granulation (QbCon?; L.B. Bohle, Ennigerloh, Germany) using in-line and on-line laser diffraction. The influence of varying process parameters and excipient formulations was studied and evaluated with the prospect of using this technique to develop control loops. For this purpose, residence time parameters were assessed. In- and on-line data was compared with off-line laser diffraction and dynamic image analysis data. Results The system successfully monitored the granule size distribution in a variety of process parameters and throughputs (up to 27.5 kg/h). It was sensitive to changes in process parameters and changes in material blends, which could pose a potential threat to the final drug products’ quality. Average event propagation time from the compaction zone to the laser diffraction system of 17.7 s demonstrates the systems’ fast reaction time. Conclusion Results highlight laser diffraction as a valuable method of in- and on-line size determination and allow for the development of a control strategy using this principle.
关键词： Process analytical technologies,Laser diffraction,Continuous manufacturing,Roll compaction/dry granulation,Process monitoring
更新于2025-09-23 15:19:57
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An alumina rotary kiln monitoring system based on flame image processing
摘要： In order to monitor the combustion condition and improve the product material quality, a digital image acquisition and processing method is adopted in alumina-sintering process. Two digital properties of flame grade and material grade are obtained by image data analyzing and smooth filtering, which provide reliable reference for operational optimization and automatic control of rotary kilns. This image acquisition system improves the operation of kiln effectively and reduces the working intensity and the manufacture cost.
关键词： flame analyzing,Rotary kiln,image processing,sintering process,monitoring system
更新于2025-09-19 17:15:36
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A convolutional neural network for prediction of laser power using melt-pool images in laser powder bed fusion
摘要： In laser powder bed fusion, a convolutional neural network could build a good regression model to predict a laser power value from a melt-pool image. To empirically validate it, we used the acquired image data from a monitoring system inside metal additive manufacturing equipment and optimally configured a convolutional network by the grid search of hyper-parameters. The proposed network showed only 0.12 % of test images were out of the criterion for judging the predicted laser power value to be reliable and showed more accurate results than deep feed-forward neural network in the prediction of laser power states unseen in training steps. We expect that the proposed model could be utilized to discover the problematic position in additive-manufactured layers causing defects during a process.
关键词： convolutional neural network,melt-pool image,process monitoring,metal additive manufacturing,laser powder bed fusion
更新于2025-09-19 17:13:59