Bead Quality Research Articles

Role of STIMULAN in chronic osteomyelitis-A randomised blinded study on 95 patients comparing 3 antibiotic compositions, bead quality, forming & absorption time

IntroductionChronic Osteomyelitis is a well-known clinical entity affecting patients holistically and presents with multiple treatment challenges. Local antibiotic delivery with biodegradable drug carriers has shown promising results. Materials and methodsProspective multicenter study performed at 2 centers from November 2021 to January 2023 on 95 osteomyelitis patients treated with surgical debridement & STIMULAN™ for local antibiotic delivery. Patients were randomized into 3 groups. Authors compared antibiotic combinations, bead quality, bead setting, and resorption time for calcium sulfate beads- STIMULAN™. Additionally, organisms isolated, WBC Turnover time, Hypersensitivity Reactions, Recurrence, and Revision Rates were documented. Results95 patients underwent surgical debridement and STIMULAN™ bead application for chronic osteomyelitis. The proximal 1/3rd tibia was commonly affected. The most common symptoms were sinus and pus discharge in 96.84 % & 86.31 % of patients respectively (p < 0.001). Staphylococcus aureus & MRSA were isolated in 37.8 % & 29.4 % of the patient's wound culture respectively. Bead setting time in Descending order was Group 3 > Group 2 > Group 1 (p < 0.001). Bead setting first in Group 1 followed by Group 3 & 2. On compression, Group-1 beads withstood maximum compression forces & had smooth even bead surfaces. On radiographs, 1/3rd bead volume in ascending order was Group 3 > Group 2 > Group 1 (p < 0.001). 2/3rd reduction in ascending order was Group 3 > Group 2 > Group 1. Complete bead absorption was earliest seen in Group 3 followed by Group 2 & Group 1 (p < 0.001). Recurrence in 2 patients (Group 2) at 6 weeks. Revision rate: 2.10 %. There were no incidences of hypersensitivity. Suture removal was done at 16 ± 2 days. ConclusionSTIMULAN™ combination with tobramycin, vancomycin, and gentamycin is stable, and forms uniform beads with predictable drug elution & bead resorption with negligible side effects. A mixture with higher liquid content sets later, forms softer beads, and resorbs earlier.

Parametric influence and effect of cooling channel on bead geometry profiles of ER70S-6 manufactured using wire arc additive manufacturing

This study investigated the complex relationship between key process parameters and their effects on weld bead geometrical profile in wire arc additive manufacturing (WAAM) of ER70S-6 low-carbon steel for part production. Specifically, the influence of wire feed rate (WFR), traverse speed (TS), and voltage (U) on weld bead height (WBH), weld bead width (WBW), and weld bead penetration (WBP) was meticulously analyzed. Research methodology integrated the Taguchi technique, analysis of variance (ANOVA), regression modeling, and gray relational analysis (GRA) to investigate and optimize process parameters. Results revealed distinct patterns, with increasing WFR leading to proportional increases in WBH, while elevated TS or U results in reduced WBH due to their impact on arc behavior and heat input. Conversely, WFR and U exhibit notable effects on WBW and WBP, underscoring the importance of optimizing process parameters for desired weld bead geometries. To tackle multi-objective optimization, GRA efficiently determines optimal process parameters for WBH, WBW, and WBP: WFR at 6 m/min, TS at 4 mm/sec, and U at 24 V. Furthermore, the inclusion of a cooling channel beneath the substrate plate significantly influences weld bead geometry, enhancing WBH and WBW while impacting WBP. The cooling channel’s ability to dissipate heat promotes faster solidification, ultimately improving weld bead quality and integrity. These findings offer valuable comprehensions for improving WAAM processes and enhancing the efficiency and quality of part fabrication.

Effect of Position of Robotic Gas Metal Arc Welding on Bead Quality and Multi-objective Optimization Through Gray Relational Analysis

Effect of Position of Robotic Gas Metal Arc Welding on Bead Quality and Multi-objective Optimization Through Gray Relational Analysis

Performance optimization and investigation of metal-cored filler wires for high-strength steel during gas metal arc welding

Abstract This study examines the utilization of metal-cored filler wire in conjunction with the gas metal arc welding (GMAW) technique for welding high-strength S690QL steel. Since welding parameters significantly impact the bead quality and weld joint integrity, the main objective was to identify the optimal welding parameters. To achieve this, the input variables including the current (A), voltage (V), and gas flow rate (GFR), and their effects were evaluated for reinforcement (R), width (W), depth of penetration (DOP), and the width of the heat-affected zone (HAZ). For a more efficient and cost-effective investigation, a Box–Behnken design, which is based on response surface methodology, was used for bead-on-plate trials. Mathematical regression models, derived from experimental data, were rigorously validated using the analysis of variance, main effects plots, residual analysis, and the R 2 and Adj. R 2 values. Additionally, the heat transfer search (HTS) algorithm was employed for process optimization. While single-objective optimization provided optimal settings for individual responses, simultaneous optimization aimed to strike a balance between multiple, sometimes conflicting, objectives. This comprehensive approach resulted in specific values, including a reinforcement (R) of 4.285 mm, a width (W) of 9.906 mm, a DOP of 2.039 mm, and an HAZ width of 2.020 mm. These values were achieved with specific input parameters: current (221 A), voltage (24 V), and GFR (21 L·min−1). The Pareto solutions offered a nuanced selection of the most suitable configuration, taking into account the desired values for R, W, DOP, and HAZ. The close alignment between predicted and experimentally measured values for the responses highlights the precision and suitability of the HTS algorithm in estimating critical bead geometries during GMAW of S690QL plates.

Initial experiments to regenerate the surface of plasma-facing components by wire-based laser metal deposition

Plasma-facing components (PFC) in nuclear fusion reactors are exposed to demanding conditions during operation. The combination of thermal loads, plasma exposure as well as neutron induced damage and activation limits the number of materials suitable for this application. Due to its properties, tungsten (W) is foreseen as plasma-facing material (PFM) for the future DEMOnstration power plant. It is considered suitable due to its exceptionally high melting point, excellent thermal conductivity, low tritium retention and low erosion resistance during plasma exposure. But even tungsten armored PFCs have a limited lifetime due to, among other factors, surface erosion and the resulting thickness reduction of the armor material.In-situ local deposition of tungsten by means of additive manufacturing (AM) could counteract surface erosion and thus increase the service life span of PFCs. After evaluation of the potential AM processes qualified for this task, the wire-based laser metal deposition (LMD-w) process was selected as the most suitable process. First trials were conducted to examine if it is possible to reliably deposit tungsten onto tungsten substrate using the LMD-w process. In these first studies, single welding beads were generated, and in later experiments, entire layers were created from several welding beads which are arranged next to each other. To ensure reproducibility of the results, the substrate temperature was kept constant. Further experiments aimed at the elimination or minimization of problems such as oxidation, occurrence of balling defects, porosity, cracking, surface waviness and insufficient connection to the substrate. To increase the welding bead quality, the input parameters like laser power, deposition velocity, wire feed rate, inert gas flow, as well as the wire position were optimized. Furthermore, stacking of several layers, as well as the remelting of an already created layer, were carried out and investigated. This study represents the first steps in testing the feasibility of an in-situ surface regeneration concept for PFCs.

Performance evaluation of sperm concentration, motility, and morphological analysis for GSA-810 series of sperm quality analysis system.

The performance evaluation of each computer-assisted sperm analysis (CASA) system may provide a basis for the interpretation of clinical results and further improvement of the CASA system. The accuracy of the GSA-810 CASA system was evaluated by detecting latex bead quality control products. The precision of sperm concentration, morphology, and percentages of progressively motile sperm (PR) were evaluated by coefficient of variation (CV). Three samples with sperm concentration of about 100 × 106 /mL were diluted to evaluate the linear range. The detection values of latex beads were within the range of target values. The CVs of sperm concentration and PR were significantly and negatively correlated with sperm concentration (r = -0.561, p = 0.001) and PR value (r = -0.621, p < 0.001), respectively. The R2 values of the linear range of sperm concentration were ≥0.99. There was no significant difference in sperm motility and PR within 1-10 min at 36.5°C ± 0.5°C. The coincidence rates of sperm morphology and sperm head morphology for 36 semen samples analyzed by the GSA-810 system and manual method were 99.40% and 99.67%, respectively. The CVs of the percentage of sperm with abnormal morphology and percentage of sperm with abnormal head morphology were less than 5%. The GSA-810 system can accurately analyze normal semen samples, but the repeatability of the results is poor for oligozoospermia and asthenozoospermia samples. The future CASA system for analyzing sperm morphology should focus on recognizing the middle and tail segments of a spermatozoon.

Building ultra-thin Inconel 718 sheet joints using low-frequency PLBW scheme: Weld bead quality, keyhole dynamics, and solidification characteristics

Low-frequency pulsed laser beam welding (PLBW) was employed in building 0.32 mm-thick Inconel 718 superalloy butt joints which are frequently applied in manufacturing high-temperature functional units in the aviation industry. Several process parameter combinations concerning peak laser power, welding speed, and pulse frequency were implemented to explore the macro morphology, microstructure, and mechanical properties of the welded joints. Examinations exhibit that the resulting weld beads possess high continuity at the surface with an overlap factor ranging from 0.58 to 0.73. The cross-sectional profile changes from a V-shape to an H-shape with increasing heat input. Finer grain structures composed of γ matrix and γ/Laves eutectic penetration are observed within the FZ center, as compared to that near the fusion line. Excellent performance is achieved in microhardness and tensile tests. Numerical simulation based on an integrated mathematic model reveals periodic keyhole and weld pool dynamics depending on the pulsing laser power. During a typical pulse interval, keyhole geometry collapses within a fraction of a millisecond, leading to a sharp cooling stage at ∼4 × 106 K/s, and then, the melt cools due to the thermal convection with a normal cooling rate of 105 K/s. The full growth of the adjacent weld spot results in the secondary melting zone (SMZ), wherein the columnar dendrites can be refined mainly due to the heterogeneous nucleation as compared to the primary melting zone (PMZ).

Welding Bead Inspection Using Image and Multi-Sensor Fusion

Welding is a crucial manufacturing technique utilized in various industrial sectors, playing a vital role in production and safety aspects, particularly in shear reinforcement of dual-anchorage (SRD) applications, which are aimed at enhancing the strength of concrete structures, ensuring that their quality is of paramount importance to prevent welding defects. However, achieving only good products at all times is not feasible, necessitating quality inspection. To address this challenge, various inspection methods were studied. Nevertheless, finding an inspection method that combines a fast speed and a high accuracy remains a challenging task. In this paper, we proposed a welding bead quality inspection method that integrates sensor-based inspection using average current, average voltage, and mixed gas sensor data with 2D image inspection. Through this integration, we can overcome the limitations of sensor-based inspection, such as difficulty in identifying welding locations, and the accuracy and speed issues of 2D image inspection. Experimental results indicated that while sensor-based and image-based inspections individually resulted in misclassifications, the integrated approach accurately classified products as ‘good’ or ‘bad’. In comparison to other algorithms, our proposed method demonstrated a superior performance and computational speed.

Development of an Arc Image Classification Algorithm in Tip-Rotating Arc Welding using Camera Image Monitoring and Deep Learning

In this study, we developed a welding system and welding monitoring system for GMA (Gas Metal Arc) aluminum welding using a tip-rotation arc welding torch. Welding was performed under various conditions, including suitable, low-heat, and high-heat input conditions. For welding monitoring, current and voltage were measured, and arc images were obtained. After the experiments, arc images were analyzed and classified based on the bead quality and cross-sectional analysis data. To develop a welding quality prediction model using arc images, a CNN-based model was developed. A total of 5,203 images were trained, and the quality was predicted for 631 images. The prediction accuracy was 99.88% for training data, and the possibility of assessing the quality of welded joints based on arc images during welding was confirmed.

The role of filler wire and scanning strategy in laser welding of difficult-to-weld aluminum alloys

AbstractLaser welding of dissimilar aluminum alloys has gained interest over recent years, especially for the production of lightweight components. Pore and crack formation is one of the most critical factors to be taken into consideration for such applications, in particular when one or more parts are produced by die casting or additive manufacturing (AM). Current laser systems offer several methods for defect reduction and process control, while optimized process strategies must be correlated to key factors influencing welding outcomes. In light of these aspects, the current paper investigates the welding of AA6082 sheets with AlSi10Mg parts produced by AM in a lap-joint configuration typical of battery housings in the e-mobility industry. Both laser welding with and without filler wire are investigated, along with the potential advantages of using a wobbling scanning strategy, in order to understand the impact of process strategies on weld bead quality. The importance of process parameter optimization is highlighted for all of the employed strategies, with special emphasis on defects, weld bead chemical composition, joint morphology, and dilution between the materials involved. The findings demonstrate that by introducing filler wire and employing active wobbling, highly reflective alloys can be welded correctly (porosity below 1%, equivalent ultimate strength up to 204 MPa) with good tolerance to variations in process parameters, while filler wire can be excluded in high-productivity welding where linear scanning is employed and detailed optimization of process parameters is performed (porosity below 2%, equivalent ultimate strength up to 190 MPa).

Effect of Mechanical Stirring on High-Speed GMAW Hump Bead.

High-speed GMAW tends to be accompanied by periodic humping defects, thereby reducing the weld bead quality. A new method was proposed to actively control the weld pool flow for eliminating humping defects. A high-melting point solid pin was designed and inserted into the weld pool to stir the liquid metal during the welding process. The characteristics of the backward molten metal flow were extracted and compared by a high-speed camera. Combined with particle tracing technology, the momentum of the backward metal flow was calculated and analyzed, and the mechanism of hump suppression in high speed GMAW was further revealed. The stirring pin interacted with the liquid molten pool, resulting in a vortex zone behind the stirring pin, which significantly reduced the momentum of the backward molten metal flow, and thus it inhibited the formation of humping beads.

The influence of GMAW correction parameters on stabilizing the deposition characteristics for wire arc additive manufacturing

The present work investigates the effects of correction parameters, viz. Arc Length Correction (ALC), Dynamic Correction (DC), and Pulse Correction (PC) on the deposition of ER70S-6 filler wire on a mild steel plate using two modes of the GMAW process, i.e., Cold Metal Transfer (CMT) and Pulsed mode. Controlling the heat input to improve the bead quality with varying correction parameters is investigated. The changes in welding current (I) and voltage (V) waveforms are explored in synchronization with high-speed arc imaging and the consequent effect on heat input, frequency, and stability of the I-V characteristics. Considering the above changes, an analysis of the influence of correction parameters on bead width, height, penetration, and microhardness is done. The variability in the above-stated weld bead properties along the length of deposition is investigated to establish a set of correction parameters most likely to provide a stable and consistent deposition. Heat input increases with increasing ALC and decreases with increasing DC and PC for a constant wire feed rate and welding speed. Bead width and penetration increase while bead height and microhardness decrease with heat input. The deviations in bead dimensions along the length of deposition directly correlate with the deviations in instantaneous heat input. The above results render the process much-needed flexibility and consistency for advanced welding and Wire Arc Additive Manufacturing (WAAM) applications.

Effect of operating parameters of hybrid TIG-MIG welding on mechanical properties and weld bead quality: A review

Effect of operating parameters of hybrid TIG-MIG welding on mechanical properties and weld bead quality: A review

Deposition quality and efficiency improvement method for additive manufacturing of Ti–6Al–4V using gas metal arc with CMT

In this study, the method to improve the bead quality and increase the wire-feed deposition efficiency propose in the CMT-GMA (cold metal transfer-gas metal arc) process of Ti-6Al-4 V alloy deposition. The proposed method uses He shielding gas to improve the Ti deposition quality by increasing the wettability through the effective arc energy transfer realized by suppressing the adverse effect of cathode spot on the molten pool. The cathode spot is dispersed by the high ionization energy of He shielding gas, which improves the Ti deposition quality owing to the stability, narrow tip, and broad tail of the arc, which enables a bead shape that improves the sound deposition quality. Increasing the detachment current increased the deposition rate, attributed to the electromagnetic force-induced separation in the molten bridge and increase in droplet repetition. Under a detachment current of 290 A and when using the He shielding gas, the deposition rate was 2.69 kg/h, which was 20.5 % higher than that under a detachment current of 50 A and when using Ar shielding gas. Through multilayer deposition, the deposition efficiency in single-bead multilayer deposition (1 ×5) was reduced to 30.1 % under Ar shielding gas and to 12.5 % under He shielding gas. In the case of multi-bead multilayer deposition (5 ×5), the Ar shielding gas induced cavities in the deposition structure. This result confirmed that the application of He shielding gas can help fabricate a high-density multilayer structure without interlayer defects.

Luminescence encoding of polymer microbeads with organic dyes and semiconductor quantum dots during polymerization

Luminescence-encoded microbeads are important tools for many applications in the life and material sciences that utilize luminescence detection as well as multiplexing and barcoding strategies. The preparation of such beads often involves the staining of premanufactured beads with molecular luminophores using simple swelling procedures or surface functionalization with layer-by-layer (LbL) techniques. Alternatively, these luminophores are sterically incorporated during the polymerization reaction yielding the polymer beads. The favorable optical properties of semiconductor quantum dots (QDs), which present broadly excitable, size-tunable, narrow emission bands and low photobleaching sensitivity, triggered the preparation of beads stained with QDs. However, the colloidal nature and the surface chemistry of these QDs, which largely controls their luminescence properties, introduce new challenges to bead encoding that have been barely systematically assessed. To establish a straightforward approach for the bead encoding with QDs with minimized loss in luminescence, we systematically assessed the incorporation of oleic acid/oleylamine-stabilized CdSe/CdS-core/shell-QDs into 0.5–2.5 µm-sized polystyrene (PS) microspheres by a simple dispersion polymerization synthesis that was first optimized with the organic dye Nile Red. Parameters addressed for the preparation of luminophore-encoded beads include the use of a polymer-compatible ligand such as benzyldimethyloctadecylammonium chloride (OBDAC) for the QDs, and crosslinking to prevent luminophore leakage. The physico-chemical and optical properties of the resulting beads were investigated with electron microscopy, dynamic light scattering, optical spectroscopy, and fluorescence microscopy. Particle size distribution, fluorescence quantum yield of the encapsulated QDs, and QD leaking stability were used as measures for bead quality. The derived optimized bead encoding procedure enables the reproducible preparation of bright PS microbeads encoded with organic dyes as well as with CdSe/CdS-QDs. Although these beads show a reduced photoluminescence quantum yield compared to the initially very strongly luminescent QDs, with values of about 35%, their photoluminescence quantum yield is nevertheless still moderate.

Blue laser welding of low thickness Ni-coated copper and mild steel for electric vehicle (EV) battery manufacturing

Modern advancements in blue lasers offer a promising alternative to conventional infrared laser welding of highly-reflective battery materials. In this study, a high-power blue laser system was used to weld the low thickness Ni-coated copper and mild steel used in 18650-type cylindrical cells. The effect of laser power on the penetration depth, interface width, and weld bead quality was studied. The weld microstructure was characterized by employing optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The mechanical performance of the welds was evaluated through peel testing and microhardness measurements. The results show that the penetration depth and weld width increased with laser power. Increasing the laser power to more than 1.3 kW resulted in a damaging effect on weld bead quality creating defects such as crack, under-fill, and distortion due to excessive heat input. Weld samples fractured in the heat-affected zone of Ni-coated copper during peel testing due to grain growth in copper. The maximum peel strength of 158.8 N was achieved for the 1.2 kW sample. The formation of a composite microstructure between Cu and Fe with a higher hardness than parent metals was observed inside the weld nugget. The hardness of this zone increased with the laser power due to an increase in the amount of Fe, reaching 185 HK for the 1.5 kW sample. By exposure to a corrosive environment, the peel strength drastically decreased and the failure occurred at the weld interface. For the 1.2 kW sample, the peel strength was reduced to around 57 N. The process initially developed for coupons of Ni-coated copper and mild steel was further tested on the positive and negative tabs of 18650-type cylindrical cells. The weld microstructure showed a lack of defects. However, due to varying thicknesses and associated heat sinks further process refinement is required for optimum joint quality.

Hierarchical bead materials multi-property design for wire-feed laser additive manufacturing

Wire-feed laser additive manufacturing has gained attention for years with its promises of high-level automation, reducing materials waste, overall costs, and large-scale volume production. However, printing material with multiple desired bead properties is a great challenge due to the high cost of experimental data and trial and error methods and the interdependent correlations among the properties. This study proposes a comprehensive multi-property integrated design framework based on learning from experiments data to enable quality control of part (bead) surface finish, geometry and microstructural properties. The printed bead process – microstructure – geometry relationships and process features' importance scores are investigated. The overall bead quality (smooth, ripple, and failed), geometry (e.g. bead height, width, fusion zone depth, fusion zone area), and microstructures characteristics are simultaneously optimized to obtain the optimal processing window. Specifically, the desirable property thresholds are defined experimentally, and the microstructures and geometries of printed beads under various process combinations have been predicted by machine learning models and visualized in a 3D contour space. With these predictions, the process parameters are optimized by passing through a set of filters to filter out undesired process candidates from a process searching space. The validation results highlight that the process parameterizations optimized by this framework can speed up the manufacturing of materials with the desired bead multi-performance.

Interrelated process-geometry-microstructure relationships for wire-feed laser additive manufacturing

Wire-feed laser additive manufacturing is an emerging fabrication technique capable of highly automated large-scale volume production that can reduce both material waste and overall cost while improving product lead times. Quality assurance is necessary for implementation into critical structural applications. However, the large number of process variables along with the cost associated with traditional trial and error methods makes this difficult. This study investigates interrelated process-geometry-microstructure relations based on learning from experiments that will enable improved quality control along with consistent overall surface, geometric and microstructural features of the part. Specifically, an experimental dataset across multiple process variables and output characteristics in terms of overall bead quality, geometric shape (i.g. bead height, width, fusion zone depth, etc.), and microstructures are collected. The predicted process-geometry-microstructure relations are then captured by virtue of data-driven machine learning models. The properties of printed beads are visualized based on an extensive range of processing space within a 3-dimensional contour map. The insights and impacts of process variables on bead morphology, geometric and microstructural features are comprehensively investigated for quality improvement during manufacturing processes.

Numerical and experimental investigation for the cladding of AISI 304 stainless steel on mild steel substrate using Gas Metal Arc Welding

In the present study, Gas Metal Arc Welding (GMAW) is used to deposit AISI 304 stainless steel layer on the mild steel substrate. The cladding parameters like welding voltage and feed rate have been varied to identify the deposited AISI 304 stainless steel bead profile and factors affecting the bead deposition on the mild steel substrate. Microscopic and EDS analysis confirms the successful deposition of the stainless steel layer on the mild steel substrate. The GMAW parameters like welding voltage and wire feed rate (WFR) govern the AISI 304 clad bead quality like clad profile, heat affected zone (HAZ), and clad penetration. A numerical model has also been developed using a double ellipsoidal heat source to identify the effect of welding parameters on the clad bead. The developed numerical model identifies the temperature distribution along with the clad bead profile and the model is identical with the experimental results. The experimental results showed that a non-uniform weld bead formation has been observed at lower voltage (14 V) and low WFR (3 m/min). The clad bead quality has improved with an increase in the welding voltage (16 V & 18 V) and wire feed rate (5 m/min & 7 m/min). However, cladding at a high wire feed rate (7 m/min) results in low dilution of the clad material with the substrate.

To Investigate the Weld Bead Hardness at Various Current through TIG Welding

In the industrial industry, TIG welding is the most frequent method of putting metals together. The electrode is held at a 10°–15° angle to the vertical by the welder while he initiates the weld by striking an arc and creating a puddle. By moving the electrode and arc in tandem, the welder "pushes" the molten metal forward and toward weld. welder strength of a building is determined by the quality of its weld beads. The weld's mechanical qualities are mostly enhanced by the weld's quality. The writers of this article explain how to weld with high weld bead quality by using the proper welding parameters. In this research, it has been proven that the hardness of welded joints improves with the increase in welding current up to 110 A for 6 mm thick plates, and afterwards declines with the rise in welding current. Splash and damage to the workpiece could occur when the current is raised to an excessively high level. Because the workpiece is so thin, high current might cause the material gap to grow. This practise may result in an increased weld affected area and a longer time to deposit the same amount of filler material, as well as damage from high heat. Inverted microscopic analysis of the weld zone was performed in order to assess the effect of the welding parameters on the weld quality. As part of the TIG weld bead quality improvement process, dye penetration testing is performed.