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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
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Qi, Huan
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Seenawat, Mongkol
;
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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Effect of micro-particles on rough surface spur gears under TEHL with non-Newtonian lubricant
(2016-01-01)
Mongkol, Mongkolwongrojn
;
Jesda, Panichakorn
This paper presents the performance characteristics of rough surface spur gears under thermo-elastohydrodynamic lubrication (TEHL) with non-Newtonian solid-liquid lubricant based on a Power law viscosity model. The bi-phase lubricant contains oil with Molybdenum disulfide particles. The time dependent modified Reynolds equation, elasticity equation, powder load carrying capacity, and energy equation with initial conditions were formulated and solved numerically using a multigrid multilevel with full approximation technique for an involute spur gear. In this analysis, the normal load and overloads are applied on either two pairs or one pair of gear teeth respectively. The transitions from two pairs to one pair and vice versa are modeled as a step variation of load. The effects of solid particle concentration, diameter of solid particle and surface roughness were examined in the region along the line of action of the meshing gear. The results show that both solid particle concentration and surface roughness affect significantly the film thickness, film temperature and friction coefficient, but the diameters of solid particle are relatively insignificant for rough TEHL.
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Simultaneous optimization of dimensional accuracy and surface roughness for finishing cut of wire-EDMed K460 tool steel
(2013-07-01)
Kanlayasiri, Kannachai
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Jattakul, Prajak
The aim of this research was to determine an optimal cutting condition of dimensional accuracy and surface roughness for finishing cut of wire-EDMed K460 tool steel. The cutting variables investigated in this study encompassed cutting speed, peak current, and offset distance. Box-Behnken design was employed as the experimental strategy, and multiple response optimization on dimensional accuracy and surface roughness was performed using the desirability function. Results showed that both peak current and offset distance have a significant effect on the dimension of the specimen while peak current alone affects the surface roughness. The optimal cutting condition was at 2 A peak current and 772 μm offset distance. Since neither dimension nor surface roughness was affected by cutting speed, the speed was thus set at the highest of 5.5 mm/min to maximize the production rate. Confirmation tests on the optimal cutting condition were executed by which all cut specimens were shown to be within the specifications. © 2013 Elsevier Inc.
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Effect of liquid-solid lubricant on mixed lubrication in line contact
(2012-01-18)
Sountaree, Rattapasakorn
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Jesda, Panichakorn
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Mongkol, Mongkolwongrojn
This paper presents the performance characteristics of two surfaces in line contact under isothermal mixed lubrication with non-Newtonian liquid-solid lubricant base on Power law viscosity model. The time dependent Reynolds equation, elastic equation and viscosity equation were formulated for compressible fluid. Newton-Raphson method and multigrid technique were implemented to obtain film thickness profiles, friction coefficient and load carrying in the contact region at various roughness amplitudes, applied loads, speeds and the concentration of solid lubricant. The simulation results showed that roughness amplitude has a significant effect on the film pressure, film thickness and surface contact pressure in the contact region. The film thickness decrease but friction coefficient and asperities load rapidly increases when surface roughness amplitude increases or surface speed decreases. When the concentration of solid lubricant increased, friction coefficient and asperities load decrease but traction and film thickness increase. © (2012) Trans Tech Publications, Switzerland.
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Stability analysis of rough journal bearings under TEHL with non-Newtonian lubricants
(2010-05-01)
Mongkolwongrojn, Mongkol
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Aiumpronsin, Chatchai
The combined effects of surface roughness and lubricants rheology on stability of a rigid rotor supported on finite journal bearing under thermal elastohydrodynamic lubrication have been investigated using the transient method. The newly derived time dependent modified Reynolds and the adiabatic energy equations were formulated using a non-Newtonian Carreau viscosity model. The simultaneous systems of modified Reynolds equation, elasticity equation, energy equation, and the rotor motion equation with initial conditions were solved numerically using multigrid multi-level method with full approximation technique. From the characteristic equation, the instability threshold is then obtained with various surface roughness parameters and the elastic modulus of the bearing liner materials. The results show that stability of the bearing system deteriorates with decreasing both the power law exponent and the elastic modulus of bearing liner material. The rough surface journal bearing with transverse pattern under TEHL regime exhibits better stability when compared with the rough surface journal bearing with longitudinal pattern. © 2010.
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Effects of wire-EDM machining variables on surface roughness of newly developed DC 53 die steel: Design of experiments and regression model
(2007-10-01)
Kanlayasiri, K.
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Boonmung, S.
DC53 is a newly developed cold die steel from Daido Steel, Japan. It is an improvement over the familiar cold die steel SKD11. Because DC53 is a new die steel, only little information is available in literature for its machining characteristics. This paper presents an investigation of the effects of machining variables on the surface roughness of wire-EDMed DC53 die steel. In this study, the machining variables investigated were pulse-peak current, pulse-on time, pulse-off time, and wire tension. Analysis of variance (ANOVA) technique was used to find out the variables affecting the surface roughness. Assumptions of ANOVA were discussed and carefully examined using analysis of residuals. Quantitative testing methods on residual analysis were used in place of the typical qualitative testing techniques. Results from the analysis show that pulse-on time and pulse-peak current are significant variables to the surface roughness of wire-EDMed DC53 die steel. The surface roughness of the test specimen increases when these two parameters increase. Lastly, a mathematical model was developed using multiple regression method to formulate the pulse-on time and pulse-peak current to the surface roughness. The developed model was validated with a new set of experimental data, and the maximum prediction error of the model was less than 7%. © 2007.
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An investigation on effects of wire-EDM machining parameters on surface roughness of newly developed DC53 die steel
(2007-06-12)
Kanlayasiri, K.
;
Boonmung, S.
DC53 is a newly developed cold die steel from Daido Steel, Japan. It is an improvement over the familiar cold die steel SKD11. Because DC53 is a new die steel, only little information is available in literature for its machining characteristics. This paper investigated the effects of machining parameters on surface roughness of wire EDMed DC53 die steel. The investigated machining parameters were pulse-on time, pulse-off time, pulse-peak current, and wire tension. Analysis of variance (ANOVA) technique was used to find out the parameters affecting the surface roughness. Assumptions of ANOVA were discussed and then examined through residual analysis. Quantitative testing methods on residual analysis were employed in place of the typical qualitative testing techniques. Results from ANOVA show that pulse-on time and pulse-peak current are significant variables to surface roughness of wire-EDMed DC53 die steel. The surface roughness of test specimen increased as these two variables increased. © 2007.
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Convection to rotating disks with rough surfaces in the presence of an axial flow
(2001-08-01)
Axcell, B. P.
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Thianpong, C.
The effect of surface roughness on convective heat transfer from an axial flow to a rotating disk has been measured using the transient heating technique. A hot air flow directed at the disk was set up in a time of less than a second and local heat transfer coefficients were deduced from the temperature response of the disk surface, which was monitored using thermochromic liquid crystals. The surface roughness took the form of small, isolated square studs arranged in a square array on the disk surface; three configurations were investigated and the results were compared with data for a smooth disk. The studs increased heat transfer rates in turbulent boundary layers by about a factor of two and reduced the transitional Reynolds number by an order of magnitude. Nusselt numbers in turbulent boundary layers could be correlated approximately using a Reynolds number, which combined the influences of the axial flow and the rotational flow. © 2001 Published by Elsevier Science Inc.

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