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Coupled Electromagnetic-Thermal Multiphysics Analysis and Design Optimization of a Microwave Kiln
(2026-05-01)
Samakkarn, Chawit
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Poopanya, Piyawong
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Thongsri, Jatuporn
This study presents a multiphysics investigation of a microwave kiln for the glass-casting process, focusing on the coupled interaction between electromagnetic heating and thermal responses. The kiln (SiC-based) was experimentally tested in a household 800 W, 2450 MHz microwave oven without rotation for 5 min, with temperatures recorded at key positions using thermocouples and verified by thermal imaging. The computational framework integrates ANSYS (2021R1) High-Frequency Structure Simulator (HFSS) for electromagnetic-field and heat-generation prediction with Transient Thermal Analysis (TTA) for time-dependent temperature distribution. Validation showed agreement between simulation and experiment of the final temperature, with most errors below 4%, confirming the model’s reliability. A parametric study revealed that a thin SiC susceptor layer (1.5–2.0 mm) improves heat generation and temperature uniformity, while excessive thickness reduces heating efficiency. The optimized design improved the temperature by 2.58% compared with the original configuration at 800 W and achieved up to 38.44% improvement under specific operating conditions. These findings demonstrate that the proposed multiphysics method can support future development of small-scale glass-casting systems and sustainable recycled-glass production. Consequently, the work paves the way to Sustainable Development Goals (SDGs).
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Predictive Three-Dimensional CFD Modeling of Evaporation-Coupled PVDF/DMF Spin-Coating on Finite Square Substrates
(2026-01-01)
Vichachai, Ratiwat
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Thongsri, Jatuporn
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Wasapinyokul, Kamol
Predictive thickness control remains challenging for spin-coated polymer films on finite, noncircular substrates, particularly with solvent evaporation. This study presents a three-dimensional computational fluid dynamics framework to simulate poly(vinylidene fluoride) dissolved in dimethylformamide during spin-coating on a finite square substrate. The model resolved free-surface hydrodynamics, interfacial solvent evaporation, species transport, and concentration-dependent viscosity to capture evaporation-coupled thinning dynamics. The simulation results were corrected with a dry-film equation based on mass conservation to obtain the film profiles. Two simulated cases—nonevaporating and evaporating—were investigated for three parameters—spin-coating time, rotational speed, and solution concentration. The nonevaporating model was validated against the one-dimensional analytical solution, while the evaporating model was validated against experimental values. Both the simulated and experimental thicknesses exhibited good quantitative agreement, confirming that the model accurately captured the film formation mechanisms. Remaining discrepancies were attributed to liquid retention at the substrate edge, uncertainty in initial dispensed volume, and numerical resolution effects near the interfacial regions. The model revealed that evaporation-induced viscosity evolution significantly modified thinning behavior, particularly at low speeds and high concentrations, and amplified edge accumulation on finite substrates. This work establishes a predictive framework for thickness and profile control in spin-coated polymer films.
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Effect of Detergent, Temperature, and Solution Flow Rate on Ultrasonic Cleaning: A Case Study in the Jewelry Manufacturing Process
(2025-12-01)
Juangjai, Natthakarn
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Chaiaiad, Chatchapat
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Thongsri, Jatuporn
This research investigated how detergent type and concentration, solution temperature, and flow rate affect ultrasonic cleaning efficiency in jewelry manufacturing. A silver bracelet without gemstones served as the test sample, and the study combined harmonic response analysis to assess acoustic pressure distribution with computational fluid dynamics to examine fluid flow patterns inside an ultrasonic cleaning machine. Cleaning tests were performed under real factory conditions to verify the simulations. Results showed that cleaning efficiency depends on the combined chemical and ultrasonic effects. Adding detergent lowered surface tension, encouraging cavitation bubble formation; higher temperatures (up to 60 °C) softened dirt, making removal easier; and moderate solution flow improved the cleaning, helping to carry dirt away from jewelry surfaces. Too much flow, however, decreased cavitation activity. The highest cleaning efficiency (93.890%) was achieved with 3% U-type detergent at 60 °C and a flow rate of 5 L/min, while pure water at room temperature (30 °C) without flow had the lowest efficiency (0.815%), confirmed by weighing and scanning electron microscope measurements. Interestingly, maximum ultrasonic power concentration did not always match the highest cleaning efficiency. The study supports sustainable practices by limiting detergent use to 3%, in line with Sustainable Development Goal (SDG) 9 (Industry, Innovation, and Infrastructure).
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Airborne Dental Material Particulates and Occupational Exposure: Computational and Field Insights into Airflow Dynamics and Control Strategies
(2025-11-01)
Chanbandit, Chanapat
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Kanchanatawewat, Kanchana
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Oo, Ghaim Man
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Thongsri, Jatuporn
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Tuntiwong, Kuson
Occupational exposure to airborne polymethacrylate (PMMA) particles during dental laboratory procedures poses an underexplored health risk. This study presents the first integrated Computational Fluid Dynamics (CFD) and real-time particle monitoring investigation of 0.5 µm PMMA particle dispersion during mechanical polishing in an actual clinic. We quantitatively assessed particle behavior in 30 s exposure scenarios by examining the effects of dental professional work orientations and comparing two mitigation strategies, rear-inlet portable air cleaners (PACs) and a Box Dust Collector (BC), with an emphasis on the safety of both personnel and patients. The findings establish that operatory airflow is a primary safety determinant: aligning the workflow with the main airflow (0°). Furthermore, the combined use of PACs and BC demonstrated synergistic superiority, achieving the optimal reduction in peak concentrations and airborne residence time. PACs alone reduced working zone concentrations by up to 80%, while BC provided a crucial 40–60 s delay in initial plume dispersion. We conclude that effective exposure control requires a proactive, two-stage engineering defense: source confinement augmented by continuous ambient filtration. This research provides a robust, evidence-based foundation for defining airflow-aware ergonomic and combined engineering standards in the evolving digital era of dentistry.
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A Modern Ultrasonic Cleaning Tank Developed for the Jewelry Manufacturing Process and Its Cleaning Efficiency
(2025-10-01)
Chaiaiad, Chatchapat
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Borthai, Pawantree
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Thongsri, Jatuporn
This research details the development and evaluation of a Modern Ultrasonic Cleaning Tank (MUCT) designed to enhance cleaning efficiency in jewelry manufacturing, particularly for silver jewelry, replacing the traditional method, which was less efficient and had higher operating costs. The MUCT offers capabilities of single- or dual-frequency ultrasonic operation (28 kHz and 40 kHz) and adjustable transducer positioning. An advanced method involving computer simulations, utilizing harmonic response analysis and transient dynamic analysis, was employed to determine the acoustic pressure inside the MUCT, thereby indicating the cavitation intensity required to achieve high cleaning efficiency. Simulation results confirm that this design can distribute acoustic pressure throughout the MUCT, as intended. A prototype MUCT was assembled, and its operation was validated through foil corrosion tests, ultrasonic power concentration (UPC) measurements, and jewelry cleaning tests. The results revealed that the MUCT’s center provided the maximum UPC of 28 W/L and an acoustic pressure of 30.43 MPa, effectively operating at single and dual frequencies, and achieving superior dirt removal. The highest cleaning efficiency of 100% was achieved using dual frequency with a 97% water and 3% dishwashing liquid mixture at 60 °C, exceeding the 23.52% obtained with water at 27 °C without ultrasonic treatment. The MUCT, successfully integrated into the manufacturing process, offers customizable features to meet various cleaning needs, providing flexibility, improved performance, and cost savings.
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A Feasibility Study for the Hot-Air-Assisted Reflow Soldering Process Based on Computational Fluid Dynamics
(2024-10-01)
Kanjad, Natcha
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Chanbandit, Chanapat
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Thongsri, Jatuporn
In hard disk drive (HDD) manufacturing, a reflow soldering process (RSP) employs heat generated at the welding tip (WT) to bond tiny electrical components for assembling an HDD. Generally, the heat was generated by an electric current applied to the WT. This article reports a feasibility study of using hot air based on computational fluid dynamics (CFD), a choice to assist heat generation. First, the WT and hot air tube (HAT) prototypes were designed and created. The HAT is a device that helps to supply hot air directly to generate heat at the WT. Then, the experiment was established to measure the temperature (T) supplied by the hot air. The measure results were employed to validate the CFD results. Next, the prototype HAT was used to investigate the T generated at the WT by CFD. The comparison revealed that the T measured by the experiment was in the 106.2 °C–133.5 °C range and that the CFD was in the 107.3 °C–136.6 °C range. The maximum error of the CFD results is 2.3% compared to the experimental results, confirming the credibility of the CFD results and methodology. The CFD results revealed that the operating conditions, such as WT, HAT designs, hot air inlet velocity, and inlet temperature, influence the T. Last, examples of suitable operating conditions for using hot air were presented, which confirmed that hot air is a proper choice for a low-temperature RPS.
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The Development of a High-Efficiency Small Induction Furnace for a Glass Souvenir Production Process Using Multiphysics
(2024-09-01)
Thongsri, Jatuporn
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Poopanya, Piyawong
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Sriphalang, Sanguansak
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Pattanapichai, Sorathorn
A small induction furnace (SIF), which has the important components of copper coils, a ceramic jig, and a graphite crucible, employed for a glass souvenir production process, has been developed as a form of clean technology for multiphysics, consisting of electromagnetics analysis (EA) and thermal analysis (TA). First, two experiments were established to measure parameters for multiphysics results validation and boundary condition settings. Then, the parameters were applied to multiphysics, in which the EA revealed magnetic flux density (B) and ohmic losses, and the TA reported a temperature consistent with the experimental results, confirming the multiphysics credibility. Next, a ferrite flux concentrator was added to the SIF during development. Multiphysics revealed that PC40 ferrite, as a flux concentrator with a suitable design, could increase B by about 159% compared to the conventional SIF at the power of 1000 W. As expected, the B increases alongside the increase in power applied to the coils, and is more densely concentrated in the flux concentrator than in other regions, enhancing the production process efficacy. Lastly, the developed SIF was employed in the actual process and received good feedback from users. The novel research findings are the developed SIF and methodology, exclusively designed for this research and practically employed for a glass souvenir production process.
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Multiphysics to Investigate the Thermal and Mechanical Responses in Hard Disk Drive Components Due to the Reflow Soldering Process
(2024-09-01)
Kimaporn, Napatsorn
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Samakkarn, Chawit
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Thongsri, Jatuporn
In hard disk drive (HDD) manufacturing, a reflow soldering process (RSP) implements heat generated by the welding tip to melt a solder ball for bonding the following essential HDD components: a flexible printed circuit (FPC) and a printed circuit cable (PCC). Since the mentioned components are tiny and comprise many thin material layers, an experiment to study thermal and mechanical responses is complex and not worth it. Therefore, a static state multiphysics consisting of thermal analysis (TA) and structural analysis (SA) was employed to investigate both responses. First, the experiment was established to mimic the RSP, measuring the temperature generated by the actual welding tip. Then, the measured temperature was defined as the boundary conditions with the pressing force (F) for the TA and SA based on the actual operating conditions. As expected, the TA results revealed the temperature distribution in the HDD components, which was consistent with the theory and results from previous work and confirmed this work’s credibility. Significantly, the SA reported severe total deformation (δ) in FPC’s top and bottom ends. The maximum δ was 0.72–0.88 mm for the F of 0–1 N. The stronger the F, the greater the δ. This research highlights that multiphysics can investigate both responses in HDD components as slight as 0.1–100 microns thick, which can be used to develop a high-efficacy RSP.
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CFD—Assisted Expert System for N2-Controlled Atmosphere Process of Rice Storage Silos
(2024-03-01)
Angsrisuraporn, Phakkawat
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Samakkarn, Chawit
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Lekawat, Lertsak
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Singkhornart, Sasathorn
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Thongsri, Jatuporn
Since organic rice storage silos were faced with an insect problem, an owner solved this problem using the expert system (ES) in the controlled atmosphere process (CAP) under the required standard, fumigating insects with an N<inf>2</inf>, reducing O<inf>2</inf> concentration to less than 2% for 21 days. This article presents the computational fluid dynamics (CFD) assisted ES successfully solved this problem. First, CFD was employed to determine the gas flow pattern, O<inf>2</inf> concentration, proper operating conditions, and a correction factor (K) of silos. As expected, CFD results were consistent with the experimental results and theory, assuring the CFD’s credibility. Significantly, CFD results revealed that the ES controlled N<inf>2</inf> distribution throughout the silos and effectively reduced O<inf>2</inf> concentration to meet the requirement. Next, the ES was developed based on the inference engine assisted by CFD results and the sweep-through purging principle, and it was implemented in the CAP. Last, the experiments evaluated CAP’s efficacy in controlling O<inf>2</inf> concentration and insect extermination in the actual silos. The experimental results and owner’s feedback confirmed the excellent efficacy of ES implementation; therefore, the CAP is effective and practical. The novel aspect of this research is a CFD methodology to create the inference engine and the ES.
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Development of a Small Ultrasonic Cleaning Bath based on Harmonic Response Analysis
(2024-01-01)
Worradechaudom, Warakorn
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Chaiaiad, Chatchapat
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Thongsri, Jatuporn
This article reports the development of a 0.27 L small ultrasonic cleaning bath (SUCB) with a 45 kHz single transducer to enhance cleaning efficacy based on harmonic response analysis (HRA). First, the HRA results revealed the uneven acoustic pressure inside the SUCB emerged from the transducer, depending on the applied voltage. As expected, the higher the applied voltage, the greater the acoustic pressure, and away from the transducer, the acoustic pressure decreased, consistent with the foil corrosion test, confirming the research methodology's credibility. Then, the transducer has been redesigned to develop the SUCB. Last, using the HRA, the simulation results indicated that the redesigned transduce, adding front and back masses like a horn shape, enhanced the acoustic pressure and helped to increase cleaning efficacy compared to the conventional SUCB. The findings were applied to develop a new generation of the SUCB. This article presents a step-by-step HRA technique that can be practically used in manufacturing design.

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