Optimization of Spiral Contours for Pulsed Laser Micromachining

In this work, both qualitative and quantitative analytical approaches were used to optimize the spiral contouring technique for complete continuous micromachining of targets. During laser ablation, spiral contours on the target were created by rotational and rastering motions (oscillation) in the x–y plane, while the laser beam position was fixed. Machining quality was characterized using laser to full surface interaction time and surface roughness. The results showed an increased laser–surface interaction time at a reduced raster angle and rastering velocity with high surface roughness at high machining time.

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Micromachining of Biolox Forte Ceramic Utilizing Combined Laser/Ultrasonic Processes

Materials ◽

10.3390/ma13163505 ◽

2020 ◽

Vol 13 (16) ◽

pp. 3505

Author(s):

Basem M. A. Abdo ◽

Syed Hammad Mian ◽

Abdualziz El-Tamimi ◽

Hisham Alkhalefah ◽

Khaja Moiduddin

Keyword(s):

Surface Roughness ◽

Material Removal ◽

Thermal Damage ◽

High Surface ◽

Dimensional Accuracy ◽

Ultrasonic Machining ◽

Rotary Ultrasonic Machining ◽

Machining Time ◽

Laser Beam Machining ◽

Wide Range

Micromachining has gained considerable interest across a wide range of applications. It ensures the production of microfeatures such as microchannels, micropockets, etc. Typically, the manufacturing of microchannels in bioceramics is a demanding task. The ubiquitous technologies, laser beam machining (LBM) and rotary ultrasonic machining (RUM), have tremendous potential. However, again, these machining methods do have inherent problems. LBM has issues concerning thermal damage, high surface roughness, and vulnerable dimensional accuracy. Likewise, RUM is associated with high machining costs and low material-removal rates. To overcome their limits, a synthesis of LBM and RUM processes known as laser rotary ultrasonic machining (LRUM) has been conceived. The bioceramic known as biolox forte was utilized in this investigation. The approach encompasses the exploratory study of the effects of fundamental input process parameters of LBM and RUM on the surface quality, machining time, and dimensional accuracy of the manufactured microchannels. The performance of LRUM was analyzed and the mechanism of LRUM tool wear was also investigated. The results revealed that the surface roughness, depth error, and width error is decreased by 88%, 70%, and 80% respectively in the LRUM process. Moreover, the machining time of LRUM is reduced by 85%.

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Geometric correction for thermographic images of asteroid 162173 Ryugu by TIR (thermal infrared imager) onboard Hayabusa2

Earth Planets and Space ◽

10.1186/s40623-021-01437-w ◽

2021 ◽

Vol 73 (1) ◽

Author(s):

Takehiko Arai ◽

Tatsuaki Okada ◽

Satoshi Tanaka ◽

Tetsuya Fukuhara ◽

Hirohide Demura ◽

...

Keyword(s):

Surface Roughness ◽

High Surface ◽

Thermal Inertia ◽

Thermal Infrared ◽

Shape Model ◽

Infrared Imager ◽

Least Squares Fit ◽

Temperature Maps ◽

Pixel Scale ◽

Thermal Infrared Imager

AbstractThe thermal infrared imager (TIR) onboard the Hayabusa2 spacecraft performed thermographic observations of the asteroid 162173 Ryugu (1999 JU$$_3$$ 3 ) from June 2018 to November 2019. Our previous reports revealed that the surface of Ryugu was globally filled with porous materials and had high surface roughness. These results were derived from making the observed temperature maps of TIR using a projection method onto the shape model of Ryugu as geometric corrections. The pointing directions of TIR were calculated using an interpolation of data from the SPICE kernels (NASA/NAIF) during the periods when the optical navigation camera (ONC) and the light detection and ranging (LIDAR) observations were performed. However, the mapping accuracy of the observed TIR images was degraded when the ONC and LIDAR were not performed with TIR. Also, the orbital and attitudinal fluctuations of Hayabusa2 increased the error of the temperature maps. In this paper, to solve the temperature image mapping problems, we improved the correction method by fitting all of the observed TIR images with the surface coordinate addressed on the high-definition shape model of Ryugu (SFM 800k v20180804). This correction adjusted the pointing direction of TIR by rotating the TIR frame relative to the Hayabusa2 frame using a least squares fit. As a result, the temperature maps spatially spreading areas were converged within high-resolved $$0.5^\circ$$ 0 . 5 ∘ by $$0.5^\circ$$ 0 . 5 ∘ maps. The estimated thermal inertia, for instance, was approximately 300$$\sim$$ ∼ 350 Jm$$^{-2}$$ - 2 s$$^{-0.5}$$ - 0.5 K$$^{-1}$$ - 1 at the hot area of the Ejima Saxum. This estimation was succeeded in case that the surface topographic features were larger than the pixel scale of TIR. However, the thermal inertia estimation of smooth terrains, such as the Urashima crater, was difficult because of surface roughness effects, where roughness was probably much smaller than the pixel scale of TIR.

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Using uniform design and regression methodology of turning parameters study of nickel alloy

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-021-07584-4 ◽

2021 ◽

Author(s):

Shao-Hsien Chen ◽

Chih-Hung Hsu

Keyword(s):

Surface Roughness ◽

Tool Wear ◽

Nickel Alloy ◽

Design Methodology ◽

Cutting Tool ◽

Uniform Design ◽

Machining Time ◽

Variable Parameters ◽

Cutting Test ◽

Set Up

AbstractThe nickel alloy has good mechanical strength and corrosion resistance at high temperature; it is extensively used in aerospace and biomedical and energy industries, as well as alloy designs of different chemical compositions to achieve different mechanical properties. However, for high mechanical strength, low thermal conductivity, and surface hardening property, the nickel alloy has worse cutting tool life and machining efficiency than general materials. Therefore, how to select the optimum machining parameters will influence the workpiece quality, cost, and machining time. This research will be using a new experimental design methodology to the cutting parameter planning for nickel-based alloy cutting test, and used the uniform design methodology to cutting test to reduce the number of experiments. Three independent variable parameters are set up, including cutting speed, feed rate, and cutting depth, and four dependent variable parameters are set up, including cutting tool wear, surface roughness, machining time, and cutting force. A nickel alloy turning parameter model is built by using regression analysis to further predict the I/O relationship among various combinations of variables. The errors between actual values and prediction values are validated. When the cutting tool wear (VB) is 2.72~6.18%, the surface roughness (Ra) is 4.10~7.72%, the machining time (T) is 3.75~8.82%, and the cutting force (N) is 1.54~7.42%; the errors of various dependent variables are approximately less than 10%, so a high precision estimation model is obtained through a few experiments of uniform design method.

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

Materials ◽

10.3390/ma14102601 ◽

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.

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Effect of Optical and Morphological Control of Single-Structured LEC Device

Micromachines ◽

10.3390/mi12070843 ◽

2021 ◽

Vol 12 (7) ◽

pp. 843

Author(s):

Woo Jin Jeong ◽

Jong Ik Lee ◽

Hee Jung Kwak ◽

Jae Min Jeon ◽

Dong Yeol Shin ◽

...

Keyword(s):

Heat Treatment ◽

Surface Roughness ◽

Surface Properties ◽

High Efficiency ◽

High Surface ◽

Reduction Rate ◽

Operating Characteristics ◽

Emission Layer ◽

Light Emitting ◽

Stable Operating

We investigated the performance of single-structured light-emitting electrochemical cell (LEC) devices with Ru(bpy)3(PF6)2 polymer composite as an emission layer by controlling thickness and heat treatment. When the thickness was smaller than 120–150 nm, the device performance decreased because of the low optical properties and non-dense surface properties. On the other hand, when the thickness was over than 150 nm, the device had too high surface roughness, resulting in high-efficiency roll-off and poor device stability. With 150 nm thickness, the absorbance increased, and the surface roughness was low and dense, resulting in increased device characteristics and better stability. The heat treatment effect further improved the surface properties, thus improving the device characteristics. In particular, the external quantum efficiency (EQE) reduction rate was shallow at 100 °C, which indicates that the LEC device has stable operating characteristics. The LEC device exhibited a maximum luminance of 3532 cd/m2 and an EQE of 1.14% under 150 nm thickness and 100 °C heat treatment.

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Post-Processing and Surface Characterization of Additively Manufactured Stainless Steel 316L Lattice: Implications for BioMedical Use

Materials ◽

10.3390/ma14061376 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1376

Author(s):

Alex Quok An Teo ◽

Lina Yan ◽

Akshay Chaudhari ◽

Gavin Kane O’Neill

Keyword(s):

Surface Roughness ◽

Stainless Steel ◽

Surface Characterization ◽

High Surface ◽

Surface Characteristics ◽

Post Processing ◽

Stainless Steel 316L ◽

Processing Methods ◽

Particulate Debris

Additive manufacturing of stainless steel is becoming increasingly accessible, allowing for the customisation of structure and surface characteristics; there is little guidance for the post-processing of these metals. We carried out this study to ascertain the effects of various combinations of post-processing methods on the surface of an additively manufactured stainless steel 316L lattice. We also characterized the nature of residual surface particles found after these processes via energy-dispersive X-ray spectroscopy. Finally, we measured the surface roughness of the post-processing lattices via digital microscopy. The native lattices had a predictably high surface roughness from partially molten particles. Sandblasting effectively removed this but damaged the surface, introducing a peel-off layer, as well as leaving surface residue from the glass beads used. The addition of either abrasive polishing or electropolishing removed the peel-off layer but introduced other surface deficiencies making it more susceptible to corrosion. Finally, when electropolishing was performed after the above processes, there was a significant reduction in residual surface particles. The constitution of the particulate debris as well as the lattice surface roughness following each post-processing method varied, with potential implications for clinical use. The work provides a good base for future development of post-processing methods for additively manufactured stainless steel.

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High-quality net shape geometries from additively manufactured parts using closed-loop controlled ablation with ultrashort laser pulses

Advanced Optical Technologies ◽

10.1515/aot-2019-0065 ◽

2020 ◽

Vol 9 (1-2) ◽

pp. 101-110 ◽

Cited By ~ 1

Author(s):

Daniel Holder ◽

Artur Leis ◽

Matthias Buser ◽

Rudolf Weber ◽

Thomas Graf

Keyword(s):

Surface Roughness ◽

Closed Loop ◽

High Surface ◽

Laser Pulses ◽

Ultrashort Laser Pulses ◽

Minimum Thickness ◽

High Quality ◽

Surface Optical ◽

The Individual ◽

Ultrashort Laser

AbstractAdditively manufactured parts typically deviate to some extent from the targeted net shape and exhibit high surface roughness due to the size of the powder grains that determines the minimum thickness of the individual slices and due to partially molten powder grains adhering on the surface. Optical coherence tomography (OCT)-based measurements and closed-loop controlled ablation with ultrashort laser pulses were utilized for the precise positioning of the LPBF-generated aluminum parts and for post-processing by selective laser ablation of the excessive material. As a result, high-quality net shape geometries were achieved with surface roughness, and deviation from the targeted net shape geometry reduced by 67% and 63%, respectively.

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Investigation on the Surface Quality Obtained during Trochoidal Milling of 6082 Aluminum Alloy

Machines ◽

10.3390/machines9040075 ◽

2021 ◽

Vol 9 (4) ◽

pp. 75

Author(s):

Nikolaos E. Karkalos ◽

Panagiotis Karmiris-Obratański ◽

Szymon Kurpiel ◽

Krzysztof Zagórski ◽

Angelos P. Markopoulos

Keyword(s):

Surface Roughness ◽

Surface Quality ◽

Process Parameters ◽

Manufacturing Industry ◽

High Surface ◽

Cutting Tools ◽

Cutting Speed ◽

Depth Of Cut ◽

High Surface Quality ◽

Trochoidal Milling

Surface quality has always been an important goal in the manufacturing industry, as it is not only related to the achievement of appropriate geometrical tolerances but also plays an important role in the tribological behavior of the surface as well as its resistance to fatigue and corrosion. Usually, in order to achieve sufficiently high surface quality, process parameters, such as cutting speed and feed, are regulated or special types of cutting tools are used. In the present work, an alternative strategy for slot milling is adopted, namely, trochoidal milling, which employs a more complex trajectory for the cutting tool. Two series of experiments were initially conducted with traditional and trochoidal milling under various feed and cutting speed values in order to evaluate the capabilities of trochoidal milling. The findings showed a clear difference between the two milling strategies, and it was shown that the trochoidal milling strategy is able to provide superior surface quality when the appropriate process parameters are also chosen. Finally, the effect of the depth of cut, coolant and trochoidal stepover on surface roughness during trochoidal milling was also investigated, and it was found that lower depths of cut, the use of coolant and low values of trochoidal stepover can lead to a considerable decrease in surface roughness.

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Machining quality of high speed helical milling of carbon fiber reinforced plastics

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406221996736 ◽

2021 ◽

pp. 095440622199673

Author(s):

Adel Abidi ◽

Sahbi Ben Salem ◽

Mohamed Athmane Yallese

Keyword(s):

Surface Roughness ◽

Carbon Fiber ◽

High Speed ◽

Hole Diameter ◽

Feed Speed ◽

Carbon Fiber Reinforced Plastics ◽

Reinforced Plastics ◽

Machining Quality ◽

Fiber Reinforced Plastics

Among advanced cutting methods, High Speed Milling (HSM) is often recommended to improve the productivity and to reduce the costs of machining parts. As every cutting process, HSM is characterized by some defects like surface roughness and delamination are the main defects generated in composite materials. The aim of this experimental work is the studying of the machining quality of woven Carbon fiber reinforced plastics (CFRP) using the HSM technology. Experiments were done using different machining parameters combinations to make opened holes in CFRP laminates. This study investigated the effect of cutting speed, orbital feed speed, hole diameter on the delamination defect and surface roughness responses generated in the drilled holes. The design of experimental tests was generated using the approach of Central Composite Design (CCD). The characterization of these responses was treated with the Analysis of variance (ANOVA) and Response surface methodology (RSM). Results showed that the surface roughness is highly affected by the orbital feed speed (F) with contribution of 22.45%. The delamination factor at entry and exit of holes is strongly influenced by the hole diameter D (25.97% and 57.43%) respectively. The developed model equations gave a good correlation between the empirical and predicted results. The optimization of the milling parameters was treated using desirability function to minimize the surface roughness (Ra) and the delamination factor simultaneously.

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Surface and Sub-Surface Integrity of Ultra- Machined BK7 Using Fine and Coarse Grained Diamond Wheels

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.359-360.234 ◽

2007 ◽

Vol 359-360 ◽

pp. 234-238 ◽

Cited By ~ 4

Author(s):

Qing Liang Zhao ◽

Bo Wang ◽

Ekkard Brinksmeier ◽

Otmann Riemer ◽

Kai Rickens ◽

...

Keyword(s):

Surface Roughness ◽

Surface Integrity ◽

High Surface ◽

Coarse Grained ◽

Nanometer Scale ◽

Grinding Wheels ◽

Fine Grained ◽

Optical Glasses ◽

Diamond Grinding ◽

Surface Damages

This paper aims to evaluate the surface and sub-surface integrity of optical glasses which were correspondingly machined by coarse and fine-grained diamond grinding wheels on Tetraform ‘C’ and Nanotech 500FG. The experimental results show that coarse-grained diamond grinding wheels are capable of ductile grinding of optical glasses with high surface and sub-surface integrity. The surface roughness values are all in nanometer scale and the sub-surface damages are around several micros in depth, which is comparative to those machined by fine-grained diamond wheels.

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