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Laser surface polishing of material extrusion additively manufactured 316L stainless steel
(2026-02-01)
Hemwat, Jirayu
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Saetang, Viboon
;
Qi, Huan
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Seenawat, Mongkol
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Chankitmunkong, Suwaree
Material extrusion additive manufacturing (MEX) provides a cost-effective pathway for fabricating metallic components; however, its industrial use remains limited by surface defects and high roughness. This study evaluates nanosecond laser polishing (LP) as a post-processing method to improve the surface characteristics of 316L stainless steel produced by Bound Metal Deposition (BMD). The objective is to understand how laser beam diameter, scan speed, and processing atmosphere (air vs. argon) influence surface integrity. Polishing experiments were performed using 50 W and 100 W laser power with beam diameters of 200 and 400 μm at scanning speeds of 100–400 mm/s. Areal roughness (S<inf>a</inf>), surface waviness (W<inf>a</inf>), surface chemistry, subsurface microstructure, and electrochemical response were systematically characterized. Laser polishing reduced S<inf>a</inf> from 2.003 μm to 0.371 μm (81 % reduction) and W<inf>a</inf> by up to 43 %. Polishing in argon produced cleaner melt tracks with minimal oxidation, a refined remelted layer, and enhanced passive film formation, leading to improved corrosion resistance (E<inf>corr</inf> improved from −0.466 V to −0.062 V). These findings demonstrate that LP effectively mitigates the surface limitations of BMD-fabricated stainless steel and provide process guidelines for achieving high-quality functional surfaces in MEX metal components.
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Effects of Surface Finishing Techniques on Properties of NiTi Coil Spring Actuators
(2025-01-01)
Premwattananarakul, Natakorn
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Srirussamee, Kasama
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Tunthawiroon, Phacharaphon
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Kumnorkaew, Theerawat
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Phukaoluan, Aphinan
This research aims to investigate the effects of surface finishing techniques on phase transformation, topography, and recovery force of NiTi coil springs designed for actuator applications. The NiTi wire, with a diameter of 1 mm, was fabricated into a helical spring with an index of 9 and 20 active coils. The spring was subsequently annealed at 550 °C for 30 min and then quenched in water. The surface finishing techniques applied to the NiTi springs included chemical etching, mechanical polishing, and sand blasting. It was observed that mechanical polishing had a strong impact on topography than both chemical etching and sand blasting. After mechanical polishing, the topography of NiTi coil springs slightly changed compared to the annealed spring. The examined surface was smooth and glistening, with a surface roughness R<inf>a</inf> of 0.175 ± 0.006 µm, nearly identical to that of the annealed spring R<inf>a</inf> of 0.116 ± 0.021 µm. Chemical etching produced a surface oxide, yet the surface became rough due to an uncontrollable chemical reaction, i.e., the R<inf>a</inf> value obtained from chemical etched surface (1.177 ± 0.156 µm) was higher than that of the mechanically polished spring. Meanwhile, sand blasting provided a blue-shaded surface corresponding to an excessive R<inf>a</inf> of 1.952 ± 0.204 µm. The DSC results revealed two peaks of R-phase and martensite transformation in the cooling curve, with only austenite transformation appearing on the heating curve. According to the DSC curve, all surface finishing techniques can reduce the latent heat and affect the associated phase transformations. Consequently, the recovery force of the spring was increased by 2–5 times the initial length. The maximum stiffness (k) of 0.129 N/mm and recovery force for the surface-finished springs were provided by mechanical polishing, while the minimum values of 0.104 N/mm were yielded by sand blasting. All experimental findings offer a framework for the development of actuator springs enhanced through each surface finishing technique.
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Analysis of effects of surface roughness on sensing performance of surface plasmon resonance detection for refractive index sensing application
(2021-09-01)
Treebupachatsakul, Treesukon
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Shinnakerdchoke, Siratchakrit
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Pechprasarn, Suejit
This paper provides a theoretical framework to analyze and quantify roughness effects on sensing performance parameters of surface plasmon resonance measurements. Rigorous coupled-wave analysis and the Monte Carlo method were applied to compute plasmonic reflectance spectra for different surface roughness profiles. The rough surfaces were generated using the low pass frequency filtering method. Different coating and surface treatments and their reported root‐mean-square roughness in the literature were extracted and investigated in this study to calculate the refractive index sensing performance parameters, including sensitivity, full width at half maximum, plasmonic dip intensity, plasmonic dip position, and figure of merit. Here, we propose a figure‐of-merit equation considering optical intensity contrast and signal‐to‐noise ratio. The proposed figure-of‐merit equation could predict a similar refractive index sensing performance compared to experimental results reported in the literature. The surface roughness height strongly affected all the performance parameters, resulting in a degraded figure of merit for surface plasmon resonance measurement.

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