Search Results (6,825)

This paper introduces an innovative automatic trajectory generation method for the robotic deburring of molded parts, effectively addressing challenges posed by burr defects and workpiece deformation common in casting and injection molding processes. Existing offline trajectory planning methods often struggle with substantial burr sizes and complex surface deformations, resulting in compromised machining quality due to over-adaptation. To overcome these issues, the proposed approach utilizes 3D vision techniques to achieve precise burr localization. A novel burr point cloud segmentation method based on feature analysis, combined with a tolerance-constrained non-rigid registration algorithm, accurately identifies burr regions and optimizes trajectory positioning within defined manufacturing tolerances. Furthermore, the method employs quantitative burr height distribution analysis to dynamically adjust robotic feed rates, significantly enhancing processing efficiency. Experimental validations demonstrated that the proposed method reduces the deburring time by up to 68% compared to conventional techniques, achieving an average trajectory deviation of only 0.79 mm. This study provides a robust, efficient, and precise solution for automating deburring operations in complex molded components, highlighting its substantial potential for industrial applications. Full article

The aim of this study was to evaluate the effect of human blood contamination, before and after hardening of the materials, on microhardness of high-viscosity Fuji IX GP Extra (Fuji IX) and resin-modified Fuji II LC (Fuji II) glass-ionomer cement (GIC) and glass-hybrid material EQUIA Forte HT (EQUIA), with and without protective coating EQUIA Forte Coat (Coat), before and after thermocycling. Four groups (n = 40): 1. Fuji IX; 2. Fuji II; 3. EQUIA and 4. EQUIA + Coat were further subdivided into 3 subgroups: (1) Control; (2) blood contamination before hardening; (3) blood contamination after hardening, resulting in a total of 12 groups of 10 samples each. Samples were prepared using teflon molds (5 mm × 2 mm). Microhardness was measured using a Vickers microhardness tester before and after thermocycling (10,000 cycles), and data were statistically analyzed (Kolmogorov–Smirnov test, ANOVA, Scheffe’s test). In the control groups, the highest microhardness was measured for EQUIA+Coat before thermocycling (70.71 ± 8.79) and after thermocycling (68.6 ± 7.65). Within the groups exposed to blood after hardening, the highest microhardness was recorded in the thermocycled EQUIA+Coat group (73.07 ± 8.85). Blood contamination before hardening negatively affected the microhardness of Fuji II, Fuji IX, and EQUIA+Coat. Exposure to blood after hardening increased the microhardness of Fuji IX and EQUIA, thermocycled Fuji IX and thermocycled EQUIA + Coat samples. Full article

The study focuses on the asymmetric shrinkage typically occurring between the upstream and downstream regions of FRP injection-molded products, a challenge that is particularly difficult to manage and improve. Specifically, two sets of four-cavity systems in one mold were utilized as the experimental platform. One set used a balanced runner (BR) system, and the other used a non-balanced runner (NBR) system. Each cavity in the four-cavity systems contained an ASTM D638 standard specimen with dimensions of 63.5 mm × 9.53 mm × 3.5 mm. Both CAE simulation and experimental methods were applied. The results show that the filling patterns from the simulation analysis closely matched those from the experimental study for both BR and NBR systems. Furthermore, by comparing the geometric shrinkage of the injected parts, significant differences were observed in the dimensional deformation in three directions (x, y, and z) between the NBR and BR systems. Specifically, at the end of the filling region (EFR), there was no noticeable difference in shrinkage along the flow direction, but the shrinkage in the cross-flow and thickness directions was reduced in the NBR system. Additionally, for the same cavity (1C) in both BR and NBR systems, the melt-rotation effect significantly reduced shrinkage in both the cross-flow and thickness directions. These findings strongly suggest that melt rotation can effectively modify the dimensional shrinkage of injection-molded parts. Moreover, fiber orientation analyses of the 1C cavity were also performed using CAE simulation for both BR and NBR systems. The results show that in the NBR system, the melt-rotation effect substantially alters the fiber orientation. Specifically, the fiber orientation tensors in the cross-flow (A₂₂) direction exhibit a decreasing trend. It can be speculated that the melt rotation alters the flow field, which subsequently changes the fiber orientation by reducing the flow-fiber coupling effect, thereby reducing the upstream-to-downstream asymmetry in the cross-flow direction. Through in-depth analysis, it is demonstrated that the correlation between the macroscopic geometric shrinkage and the microscopic fiber orientation changes is highly consistent. Specifically, in the EFR, ΔA₂₂ decreased by 0.0376, improving upstream/downstream shrinkage asymmetry in the cross-flow direction (Ly). Future work will investigate alternative melt-rotation designs and the optimization of model-internal parameters in FOD prediction. Full article

Nozzle blockage has been a critical issue for productivity and product quality since the introduction of continuous casting. Despite numerous studies on the subject, the problem persists, affecting steel production. This detrimental phenomenon causes changes in the internal nozzle geometry and severe wall irregularities that are neither symmetrical nor uniform. A common approach to studying the complex internal shape of clogged nozzles is considering nozzles with symmetrical transversal area reductions. Therefore, this study aims to quantitatively evaluate the effects of using realistic submerged entry nozzle (SEN) clogging geometries on the fluid dynamic behavior of molten steel inside the SEN and the mold and is compared to simplified symmetric reductions. A three-dimensional mathematical simulation based on the Navier–Stokes equations, the standard k − ε turbulence model, and the Volume of Fluid (VOF) method was used. The main findings indicate that symmetric reductions can only provide a qualitative prediction of the results, such as increased velocity and asymmetries at the meniscus bath level, but with errors that can reach up to 25%. Symmetric reductions fail to accurately capture the fluid dynamics inside the nozzle and the mold and should therefore be used with caution in studies that require precise flow characterization near the nozzle walls. Full article

Aluminum and its alloys are widely used in many fields, such as automotive, aerospace, and defense industries, due to their many advantages. Due to such critical applications, the quality demands are also increasing. With the recent development in technologies, studies on casting of aluminum with different alloying element additions are ongoing rapidly. Various elements are added to the alloy to provide the desired properties. In this study, the effects of 0.03, 0.06, and 0.1 wt% Er addition to A356 aluminum alloy were evaluated simply because in the literature, only 0.1 wt% and above additions were studied. Samples were prepared using permanent molds and subjected to mechanical testing and microstructural characterization. Changes in the microstructure (evaluated via SDAS and SDAL) and mechanical properties of the cast specimens were analyzed. The results showed that Er addition improved tensile strength by up to 30%, increased elongation fourfold, and enhanced toughness by a factor of 4.5. Full article

This study analyzes the nutritional quality and mycotoxin contamination of three key feed ingredients—corn, soybean meal (SBM), and sunflower meal (SFM)—imported into Morocco during the years 2019, 2020, and 2021. Samples were collected upon reception at the plant and analyzed in triplicate under standardized laboratory conditions. Chemical composition was evaluated using classical and NIR-based methods, while mycotoxin levels were assessed through ELISA and confirmed by HPLC. Corn samples from Argentina, Brazil, and Ukraine were assessed for their proximate composition and mycotoxin burden. While most nutritional parameters showed no significant differences between origins (p > 0.05), water activity (Aw) and digestible threonine content were significantly affected by origin (p < 0.01). Brazilian corn had the highest Aw (0.716), followed by Argentina (0.680), and Ukraine (0.662), a factor linked to its higher susceptibility to mold and mycotoxin development. Soybean meal from the U.S. and Argentina showed a general positive trend in favor of U.S. imports, with higher average crude protein (the CP content of American soybean meal was 46.912%, compared to 46.610% in Argentine soybean meal), fat, digestible lysine, and metabolizable energy. However, statistical differences were limited to water activity and moisture content (p < 0.05). American soybean meals are generally recognized for their consistent processing quality and superior amino acid digestibility. Sunflower meal, sourced exclusively from Ukraine, showed a steady improvement in crude protein (from 35.97% in 2019 to 36.99% in 2021) and metabolizable energy, alongside reduced crude fiber content, enhancing its nutritional value in poultry diets. The consistent use of Ukrainian SFM in Morocco reflects both supply stability and quality. Regarding mycotoxins, origin had a significant effect on several compounds. Argentine and Brazilian corn showed higher mean levels of fumonisins (1165.26 and 1019.52 ppb), ochratoxin A (2.26 and 3.02 ppb), and zearalenone (36.99 and 21.92 ppb) compared to Ukrainian corn, which consistently had the lowest levels across all major mycotoxins (e.g., fumonisins = 200 ppb; zearalenone = 4.90 ppb). Aflatoxin B1 levels remained constant at 0.2 ppb across all origins. These findings confirm the influence of geographic origin—particularly water activity—on mycotoxin risk in imported maize. Full article

Fungicide treatment is one of the most common methods for controlling fungal plant diseases. However, many phytopathogenic fungi develop resistance to fungicides. Addressing this agriculturally important issue requires comprehensive investigations into fungicide resistance. Our study aims to assess the degree and prevalence of resistance to carbendazim—one of the most widely used fungicides—in populations of Microdochium nivale, the causal agent of the deleterious plant disease pink snow mold; to explore possible relationships between carbendazim resistance and physiological and genetic traits; and to gain insight into the molecular basis of carbendazim resistance in this species. We showed that carbendazim resistance is widespread in the analyzed M. nivale populations, and that the application of carbendazim increases the proportion of resistant strains. Nevertheless, carbendazim-resistant strains are present at high relative abundance in populations that have never been exposed to fungicides. Carbendazim resistance in M. nivale is strongly associated with sequence variations in the β-tubulin gene, resulting in amino acid sequence variability that leads to differential affinity for carbendazim. Additionally, we propose a metabarcoding-based approach employing a genetic marker linked to a specific phenotypic trait to assess the ratio of genotypes with contrasting properties within a particular fungal species in environmental communities. Full article

The lower melt strength of biodegradable materials in comparison to low density polyethylenes raises serious issues regarding their processability via blown film molding. Thus, reliable rheological characterization is a viable option for assessing their efficient flow performance. The blends of poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT) modified with four chain-extending cross-linkers (CECLs) undergo shearing during extrusion and are subjected to extensional deformation during the subsequent film blowing. The shear viscosity data obtained with a capillary rheometer corresponded well to the molecular weights obtained by gel permeation chromatography, while an evaluation of elongational viscosity using a Sentmanat Extensional Rheometer failed due to sample sagging during the process of temperature setting and an unacceptable deviation from the theoretically supposed exponential decrease of sample cross-sections. Therefore, the response of the PBAT/PLA blends to elongation was determined via changes in the duration of time intervals corresponding to the rupture of elongated samples. An increased consistency of the PBAT/PLA blends with CECL, as previously indicated by dynamic mechanical analysis, differential scanning calorimetry, and scanning electron microscopy, was evaluated in this way. Full article

A lunar landing pad (LLP) represents essential initial infrastructure for establishing sustainable lunar settlements. This study investigates the feasibility of constructing LLPs through in situ resource utilization (ISRU), focusing on an innovative composite material comprising lunar regolith and the high-performance thermoplastic Polyether Ether Ketone (PEEK). The proposed manufacturing approach involves mechanically blending regolith with PEEK granules, compacting the mixture in a mold, and thermally processing it to induce polymer melting and binding. Experimental analysis indicates that a modest binder fraction (15 wt. % PEEK) yields a robust composite with a flexural strength of 14.6 MPa, although exhibiting inherently brittle characteristics. Compaction pressure emerges as a crucial factor influencing material performance. Utilizing these findings, hexagonal modular tiles were designed as the fundamental LLP elements, specifically engineered to optimize manufacturing simplicity, mechanical robustness, stackability for redundancy, and ease of replacement or repair. The tile geometry strategically mitigates brittleness-induced vulnerabilities by avoiding stress concentrations. Explicit finite element analyses validated tile performance under simulated lunar landing conditions corresponding to the European Large Logistic Lander specifications. Results demonstrated safe landing velocities between 0.1 and 0.7 m/s, governed by the binder content and compaction pressure. A clearly identified linear correlation between the binder fraction and permissible impact velocity enables predictive tailoring of the material composition, confirming the suitability and scalability of thermoplastic–regolith composites for future lunar infrastructure development. Full article

Fiber-reinforced composites (FRCs) have emerged as transformative alternatives to traditional marine construction materials, owing to their superior corrosion resistance, design flexibility, and strength-to-weight ratio. This review comprehensively examines the current state of FRC technologies in marine deck and underwater applications, with a focus on manufacturing methods, durability challenges, and future innovations. Thermoset polymer composites, particularly those with epoxy and vinyl ester matrices, continue to dominate marine applications due to their mechanical robustness and processing maturity. In contrast, thermoplastic composites such as Polyether Ether Ketone (PEEK) and Polyether Ketone Ketone (PEKK) offer advantages in recyclability and hydrothermal performance but are hindered by higher processing costs. The review evaluates the performance of various fiber types, including glass, carbon, basalt, and aramid, highlighting the trade-offs between cost, mechanical properties, and environmental resistance. Manufacturing processes such as vacuum-assisted resin transfer molding (VARTM) and automated fiber placement (AFP) enable efficient production but face limitations in scalability and in-field repair. Key durability concerns include seawater-induced degradation, moisture absorption, interfacial debonding, galvanic corrosion in FRP–metal hybrids, and biofouling. The paper also explores emerging strategies such as self-healing polymers, nano-enhanced coatings, and hybrid fiber architectures that aim to improve long-term reliability. Finally, it outlines future research directions, including the development of smart composites with embedded structural health monitoring (SHM), bio-based resin systems, and standardized certification protocols to support broader industry adoption. This review aims to guide ongoing research and development efforts toward more sustainable, high-performance marine composite systems. Full article

Wood–plastic composites (WPCs) are polymeric materials, usually thermoplastic, filled with wood flour or fibers. They are relatively durable and stiff and resistant to water. They are also, importantly, relatively cheap compared to materials with similar properties. The WPCs market has grown significantly in recent years, mainly thanks to the increasing construction and automotive markets. Currently, the global WPCs market is forecasted to reach about USD 15 billion by 2030, increasing at an impressive compound annual increase rate of about 12% until 2030. There are some review articles on WPCs written from many different points of view, e.g., the type of materials used (polymers, fillers, auxiliaries), the method of manufacturing and processing, processing properties (thermal and rheological) and functional properties, methods of designing composite products and designing (modeling) forming processes. In this article, we will summarize these different points of view and will present a thorough literature review of rheology and material processing, and more specifically, the modeling of WPCs processing. This work will be presented in relation to state-of-the-art research in the field of modeling the processing of other polymeric materials, i.e., standard (neat) polymers and polymer blends. The WPCs’ processing is significantly different from that of standard plastics due to the differences in thermo-rheological properties, diverse structures, etc. So far, the global WPCs processing models have only been developed for both gravity-fed and starve-fed single-screw extrusion. The models for twin-screw extrusion, both co-rotating and counter-rotating, as well as for injection molding, have still not been developed. WPCs show a yield stress and wall slip when extruding, which must be considered when modeling the process. As the slippage on the screw and barrel grows, the process throughput and pressure diminish, but as the slippage on the die grows, the throughput grows and the pressure diminish. As the yield stress in the screw grows, the process throughput and pressure grow, whereas as the yield stress in the die grows, the throughput diminishes and the pressure grows. Full article

Background: Children affected by unilateral cleft lip and palate (UCLP) represent a therapeutic challenge requiring the development of novel therapies, such as the implant of a bioengineered tissue—BIOCLEFT—or the use of nasoalveolar molding (NAM). The objective of this work was to evaluate the effects of NAM on the surgical and aesthetic outcomes of children with UCLP. Methods: A total of 36 children with UCLP treated at a craniofacial malformations management unit were evaluated, including 23 patients treated with presurgical NAM followed by palate surgical correction (NAM group) and 13 patients treated surgically without previous NAM (non-NAM group). Measurements were obtained from each patient immediately before palate surgery, including four linear measurements: nasal ala projection length (NAPL), nasal dome height (NDH), superoinferior alar groove position (S-I AGP), and nasal dome position (M-L NDP), and two angular measurements: columellar deviation (CD) and nasal bridge deviation (NBD). Results: When NAM was used, a significant improvement of the basilar view linear measurements of the patient’s nose was found, including the NAPL and NDH, and the frontal view linear measurement M-L NDP, but not S-I AGP. Significant improvements were also observed in the angular measurements of nasal symmetry CD and NBD. All these variables, except the S-I AGP, significantly correlated with the treatment group, and two variables—NAPL and CD—significantly contributed to generate a predictive model developed using binary logistic regression. Conclusions: These findings support the use of NAM to efficiently improve the nasal symmetry and the presurgical outcomes of patients with UCLP. Full article

To address the issue of cracking damage under extreme high-temperature rutting, which is not sufficiently considered in the selection of preventive maintenance programs, the objective of this study was to investigate the preventive maintenance-oriented minor internal damage changes in asphalt concrete with a normal maximum aggregate size of 16 mm (AC-16) under extreme high temperature (70 °C) and load (1.4 MPa) conditions. The changes in void structure within the 0–10 mm rutting depth were tracked through the rutting test and Computer Tomography (CT) image analysis. It was observed that there were notable discrepancies in the three-dimensional (3D) space distribution of void, void volume development, and void morphology between the rut impact zones and the rutted part. The impact zone exhibited a greater prevalence of voids and an earlier onset of cracking. At a rutting depth of only 5 mm, multiple top-down developed cracks (TDCs) of over 6 mm length were observed in the impact zone. At a rutting depth of 10 mm, the TDCs in the impact zone were more numerous, larger, and wider, indicating the necessity for a tailored repair program that includes milling. TDC damage caused by high-temperature rutting is predominantly observed in the upper and middle positions of the height direction, with the bottom position data exhibiting greater inconsistency due to the influence of molding. Furthermore, the combination of void morphology indicators with void volume can effectively track the occurrence and development of microcracks. However, the fine-scale assessment of compaction degree and deformation process using the equivalent void diameter indicator is not sufficiently differentiated. Full article

The final phase of the manufacturing process for any artefact involves their surface finishing operations. This phase entails the precise removal of small volumes of material to achieve a specific surface roughness, which is essential for ensuring the artefact’s post-production performance and endurance. For certain tooling, such as molds and dies, the finishing operation can be particularly significant, often equating to fifty percent of the total production time and a fifth of the overall manufacturing cost. In recent years, collaborative robotics has come to the fore. These advanced systems allow manufacturers to harness the positive attributes of robots, such as their repeatability, endurance, and strength, while simultaneously leveraging the unique benefits of human workers, including their process knowledge, problem-solving abilities, and adaptability. This co-operation between human and robotic capabilities has opened new avenues for efficiency and precision in the finishing process. This paper investigates the current advancements in collaborative robotic finishing, providing a comprehensive overview of the latest technologies and methodologies. It also highlights existing research gaps that need to be addressed to further enhance the effectiveness of these systems. Additionally, the paper suggests potential areas for future investigation, aiming to drive continued innovation and improvement in the field of collaborative robotic finishing operations. Full article

The article presents a study of the possibilities for restoring the working surfaces of molds for high-pressure casting of non-ferrous metals by laser surfacing using a filler material. Test specimens with parameters of real forming elements were manufactured. The influence of nitriding on welded layers and basic material was studied in comparison with one without nitriding. The X-ray diffraction method was used to obtain the phase composition of the surface of the samples in areas submitted to nitriding. Scanning electron microscopy (SEM) was used to determine the microstructure of the nitriding layers, welded layers and bulk material. Energy-dispersive X-ray spectrometry (EDX) was applied to investigate the chemical composition in the welded and nitrided zone. Mechanical property means of microhardness measurements were studied. Four zones were identified after nitriding in the weld area. The first zone closest to the surface with a thickness of 0.025 mm is characterized by a higher microhardness, which reaches 700 HV. The second zone, which is part of the diffusion zone, is 0.1 mm thick, and it is characterized by the same size grains with a similar shape and microhardness, which reaches 600 HV. The microhardness measured in the welded zone after nitriding is 50% greater than that without nitriding. The thickness of the diffusion zone in 1.2343 steel reaches about 0.15 mm, and the microhardness is about 900 HV near the edge, but quickly decreases to 400 HV. Full article