Analysis of Surface Roughness according to a Variable Path Condition in Laser Polishing

2018 ◽  
Vol 35 (1) ◽  
pp. 61-69
Author(s):  
Bin Li ◽  
Hyun-Woo Choi ◽  
Cheol-Soo Lee ◽  
Jong-Uk Lee ◽  
Jae-Uk Lee
Keyword(s):  
Surface Roughness ◽  
Laser Polishing ◽  
Path Condition

scholarly journals Mechanical Characterization and Thermodynamic Analysis of Laser-Polished Landscape Design Products Using 3D Printing

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2601
Author(s):  
Yue Ba ◽  
Yu Wen ◽  
Shibin Wu
Keyword(s):  
Surface Roughness ◽  
3D Printing ◽  
Fused Deposition Modeling ◽  
High Surface ◽  
Landscape Design ◽  
Laser Polishing ◽  
Fused Deposition ◽  
Design Structure ◽  
3D Printed ◽  
Stability And Accuracy

Recent innovations in 3D printing technologies and processes have influenced how landscape products are designed, built, and developed. In landscape architecture, reduced-size models are 3D-printed to replicate full-size structures. However, high surface roughness usually occurs on the surfaces of such 3D-printed components, which requires additional post-treatment. In this work, we develop a new type of landscape design structure based on the fused deposition modeling (FDM) technique and present a laser polishing method for FDM-fabricated polylactic acid (PLA) mechanical components, whereby the surface roughness of the laser-polished surfaces is reduced from over Ra 15 µm to less than 0.25 µm. The detailed results of thermodynamics and microstructure evolution are further analyzed during laser polishing. The stability and accuracy of the results are evaluated based on the standard deviation. Additionally, the superior tensile and flexural properties are examined in the laser-polished layer, in which the ultimate tensile strength (UTS) is increased by up to 46.6% and the flexural strength is increased by up to 74.5% compared with the as-fabricated components. Finally, a real polished landscape model is simulated and optimized using a series of scales.

Fundamental Study on Laser Interactions With Nanoparticles-Reinforced Metals—Part II: Effect of Nanoparticles on Surface Tension, Viscosity, and Laser Melting

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Chao Ma ◽  
Jingzhou Zhao ◽  
Chezheng Cao ◽  
Ting-Chiang Lin ◽  
Xiaochun Li
Keyword(s):  
Surface Tension ◽  
Surface Roughness ◽  
Thermophysical Properties ◽  
Melting Process ◽  
Laser Melting ◽  
Fundamental Study ◽  
Laser Polishing ◽  
Laser Manufacturing ◽  
Manufacturing Technologies ◽  
Laser Interactions

It is of great scientific and technical interests to conduct fundamental studies on the laser interactions with nanoparticles-reinforced metals. This part of the study presents the effects of nanoparticles on surface tension and viscosity, thus the heat transfer and fluid flow, and eventually the laser melting process. In order to determine the surface tension and viscosity of nanoparticles-reinforced metals, an innovative measurement system was developed based on the characteristics of oscillating metal melt drops after laser melting. The surface tensions of Ni/Al2O3 (4.4 vol. %) and Ni/SiC (3.6 vol. %) at ∼1500 °C were 1.39 ± 0.03 N/m and 1.57 ± 0.06 N/m, respectively, slightly lower than that of pure Ni, 1.68 ± 0.04 N/m. The viscosities of these Ni/Al2O3 and Ni/SiC MMNCs at ∼1500 °C were 13.3 ± 0.8 mPa·s and 17.3 ± 3.1 mPa·s, respectively, significantly higher than that of pure Ni, 4.8 ± 0.3 mPa·s. To understand the influences of the nanoparticles-modified thermophysical properties on laser melting, an analytical model was used to theoretically predict the melt pool flows using the newly measured material properties from both Part I and Part II. The theoretical analysis indicated that the thermocapillary flows were tremendously suppressed due to the significantly increased viscosity after the addition of nanoparticles. To test the hypothesis that laser polishing could significantly benefit from this new phenomenon, systematic laser polishing experiments at various laser pulse energies were conducted on Ni/Al2O3 (4.4 vol. %) and pure Ni for comparison. The surface roughness of the Ni/Al2O3 was reduced from 323 nm to 72 nm with optimized laser polishing parameters while that of pure Ni only from 254 nm to 107 nm. The normalized surface roughness reduced by nearly a factor of two with the help of nanoparticles, validating the feasibility to tune thermophysical properties and thus control laser-processing outcomes by nanoparticles. It is expected that the nanoparticle approach can be applied to many laser manufacturing technologies to improve the process capability and broaden the application space.

Surface Roughness Improvement Using Laser-Polishing Techniques

2006 ◽  
pp. 217-222
Author(s):  
Aitzol Lamikiz ◽  
J.A. Sánchez ◽  
L.N. López de Lacalle ◽  
D. del Pozo ◽  
J.M. Etayo
Keyword(s):  
Surface Roughness ◽  
Laser Polishing

scholarly journals Laser Polishing of Additive Manufactured Aluminium Parts by Modulated Laser Power

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1332
Author(s):  
Markus Hofele ◽  
André Roth ◽  
Jochen Schanz ◽  
Johannes Neuer ◽  
David K. Harrison ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Laser Power ◽  
Modulation Frequency ◽  
Reduction Rate ◽  
Initial Surface ◽  
Process Stability ◽  
Laser Polishing ◽  
Melt Pool ◽  
Power Curves

In this study a new approach to laser polishing with periodic modulated laser power in the kilohertz regime is introduced. By varying the modulation frequency and modulation time, different periodic laser power curves with varying minimum, peak and average laser power can be created. The feasibility of the method is shown by polishing of vertical built AlSi10Mg L-PBF parts with an initial roughness of Ra = 12.22 µm. One polishing pass revealed a decreasing surface roughness with increasing energy density on the surface up to Ra = 0.145 µm. An increasing energy density results in a rising remelting depth between 50 and 255 µm and a rising relative porosity of 0.3% to 4.6%. Furthermore, the thermal process stability, analysed by the melt pool length in scanning direction, reveals a steadily increasing melt pool dimension due to component heating. Multiple laser polishing passes offers a further reduced surface roughness, especially at higher modulation frequencies and provides an improved orientation independent roughness homogeneity. The process stability regarding varying initial surface roughness revealed an almost constant relative roughness reduction rate with an achievable roughness variation after two polishing passes between Ra = 0.13–0.26 µm from an initial state of Ra = 8.0−19.2 µm.

Effect of Scanning Interval on Polishing Effect of S136D Die Steel

2021 ◽  
Vol 1020 ◽  
pp. 55-59
Author(s):  
Hao Zhou ◽  
Zhen Yu Zhao ◽  
Hou Ming Zhou ◽  
Kai Li ◽  
Jing Cheng Jin
Keyword(s):  
Material Processing ◽  
Surface Roughness ◽  
Laser Scanning ◽  
Reduction Rate ◽  
Single Factor ◽  
Continuous Fiber ◽  
Laser Polishing ◽  
Die Steel ◽  
Experiment Method ◽  
Single Factor Experiment

Laser polishing technology plays an increasingly important role in the material processing technology.In order to study the influence of scanning interval on the polishing effect of S136D die steel, the single factor experiment method is used in this paper. The continuous fiber laser is used to carry out many laser polishing experiments and the influence of laser scanning interval on the surface morphology of S136D die steel is analyzed.The results show that the surface roughness of polished samples decreases first and then increases with the of scanning interval. When the scanning interval is in the range of 0.03-0.1mm, the surface roughness of samples is relatively flat, and the lowest surface roughness can be reduced to 0.781μm, and the reduction rate of surface roughness can reach 90.2%.

scholarly journals Investigation of Laser Polishing of Four Selective Laser Melting Alloy Samples

2020 ◽  
Vol 10 (3) ◽  
pp. 760
Author(s):  
Dongqi Zhang ◽  
Jie Yu ◽  
Hui Li ◽  
Xin Zhou ◽  
Changhui Song ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Layer By Layer ◽  
Metal Powders ◽  
Laser Melting ◽  
Laser Polishing

Selective laser melting (SLM) is a layer by layer process of melting and solidifying of metal powders. The surface quality of the previous layer directly affects the uniformity of the next layer. If the surface roughness value of the previous layer is large, there is the possibility of not being able to complete the layering process such that the entire process has to be abandoned. At least, it may result in long term durability problem and the inhomogeneity, may even make the processed structure not be able to be predicted. In the present study, the ability of a fiber laser to in-situ polish the rough surfaces of four typical additive-manufactured alloys, namely, Ti6Al4V, AlSi10Mg, 316L and IN718 was demonstrated. The results revealed that the surface roughness of the as-received alloys could be reduced to about 3 μm through the application of the laser-polishing process, and the initial surfaces had roughness values of 8.80–16.64 μm. Meanwhile, for a given energy density, a higher laser power produced a laser-polishing effect that was often more obvious, with the surface roughness decreasing with an increase in the laser power. Further, the polishing strategy will be optimized by simulation in our following study.

Micromelting for Laser Micro Polishing of Meso/Micro Metallic Components

2007 ◽  
Author(s):  
Tyler L. Perry ◽  
Dirk Werschmoeller ◽  
Xiaochun Li ◽  
Frank E. Pfefferkorn ◽  
Neil A. Duffie
Keyword(s):  
Surface Roughness ◽  
Spatial Frequency ◽  
Surface Profile ◽  
Laser Pulses ◽  
Sample Surface ◽  
Laser Polishing ◽  
Complex Shapes ◽  
Micro Parts ◽  
Silicon Based ◽  
Underlying Processes

The relative surface accuracy (surface roughness/feature size) of meso/micro parts fabricated by emerging meso/micro manufacturing processes is generally worse than that of macro parts fabricated by conventional processes. Meso/micro parts have unique tribology issues and surface roughness strongly impacts their performance, hence there is a demand for effective polishing of their complex shapes. A laser micro polishing method based on rapid surface micromelting is described. To develop a fundamental understanding of the underlying processes, a nickel sample was fabricated using silicon-based microfabrication and electroplating techniques. Results demonstrating the effectiveness of laser polishing using a pulsed 1064 nm Nd:YAG laser are presented. These results show that brief (200–300 ns) laser pulses can significantly improve the sample surface roughness (Ra). Additionally, by examining surface profile data in the spatial frequency domain it is clear that using pulses (up to 300 ns), laser polishing can effectively remove surface roughness features greater than 200 mm−1 in spatial frequency.

scholarly journals Laser polishing of titanium surfaces obtained by additive manufacturing process

2020 ◽  
Vol 321 ◽  
pp. 03034
Author(s):  
Benoit Rosa ◽  
Jean-Yves Hascoët
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Physical Phenomenon ◽  
Metal Deposition ◽  
Polished Surface ◽  
Laser Metal Deposition ◽  
Polishing Process ◽  
Laser Polishing ◽  
Titanium Surfaces ◽  
Five Axes

Additive Manufacturing (AM) surfaces are composed by different textures and high roughness values which tend to limit its functionalities. Laser polishing process is enabling to smooth surfaces by material melting, change surface texture and decrease surface roughness (Sa). Based on a five axes machine, which consist of milling and Laser Metal Deposition (LMD) processes, the machine is additionally integrating laser polishing process on the same architecture. This paper aims at study laser polishing of laser metal deposition of titanium surfaces. LMD of titanium surfaces are composed by chaotic texture directly induced by the physical phenomenon of the process in use. Laser polishing process (LP) has an impact on the final surface regarding a multi-scale approach. The determined operating parameters and path strategy of laser polishing process decreases surface roughness by 78% and allow smoothing the initial chaotic texture. A polished surface roughness of 6.01 μm was obtained from an initial of 27.6μm.

scholarly journals A comparative study on surface topography and micro hardness of laser polished hardened AISI D2 tool steel

2021 ◽  
Author(s):  
Zuofa Liu ◽  
Jie Zhou ◽  
Hang Wang ◽  
Qiuyun Wang ◽  
Qiang Liang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Treatment ◽  
Surface Topography ◽  
Tool Steel ◽  
Laser Surface ◽  
Laser Surface Treatment ◽  
Laser Polishing ◽  
Aisi D2 ◽  
Aisi D2 Tool Steel ◽  
Polishing Efficiency

Abstract In this work, a laser polishing-hardening (LPH) method with integration and high efficiency for the treatment of AISI D2 tool steel was proposed, and the effects of laser hardening (LH), laser polishing (LP) and LPH treatments on the surface topography and microhardness were examined. The results show that LH method had a negligible effect on the surface roughness of the treated sample, while the surface roughness Ra of LP and LPH specimens was reduced by 74.6% and 80.9% respectively, indicating that the milled surface topography had been significantly improved, especially LPH was more effective in reducing the roughness. Besides, the polishing efficiency of LPH was 10 times that of LP approach. In terms of hardness improvement, the near-surface microhardness of LH and LPH samples increased by 1.5 times and 1.3 times respectively, and the effective hardened zone (EHZ) depth was 0.42 mm and 0.24 mm respectively, demonstrating that these two laser processing methods had a beneficial effect on the cross-section microhardness of D2 tool steel, while the increase of LP on the microhardness was insignificant. The comprehensive analysis of the surface morphology and microhardness of LPH specimen indicates that LPH was a feasible laser surface treatment method for D2 tool steel. On the premise of ensuring a high surface finish, the polishing efficiency can be remarkably improved, the subsurface microhardness and EHZ depth of processed specimen can be also significantly enhanced, which provided a feasible idea for the application of laser surface treatment technology in industrial mold production.

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