Materials

Research

Jump to: Other

20 pages, 12030 KiB

Open AccessArticle

Surface Feature Prediction for Laser Ablated 40Cr13 Stainless Steel Based on Extreme Learning Machine

by Zhenshuo Yin, Qiang Liu, Pengpeng Sun, Yinuo Zhou and Zhiwei Ning

Materials 2023, 16(2), 505; https://doi.org/10.3390/ma16020505 - 4 Jan 2023

Viewed by 1007

Abstract

Determining an optimal combination of laser process parameters can significantly improve the efficiency and quality of 40Cr13 steel surface processing. In this study, two machine learning models (ELMSS and ELMPS) were proposed to predict the processing results of surface features to optimize process [...] Read more.

Determining an optimal combination of laser process parameters can significantly improve the efficiency and quality of 40Cr13 steel surface processing. In this study, two machine learning models (ELMSS and ELMPS) were proposed to predict the processing results of surface features to optimize process parameters. The prediction accuracies of the proposed models were always higher than those of traditional back propagation (BP) and radial basis function (RBF) neural networks, and the calculation time of the proposed models was significantly reduced. In comparison, the prediction accuracy ranking for ablation depth was ELMSS (92.6%), BP (89.8%), and RBF (89.6%), and for the ablation width, it was ELMSS (98.3%), BP (97.4%), and RBF (96.1%). The material removal rate was 92.4%, 91.1%, and 89.1% for ELMSS, BP, and RBF, respectively. Finally, the prediction accuracy ranking for surface roughness was 86.8%, 80.7%, and 79.5% for ELMPS, BP, and RBF, respectively. After optimization by the genetic algorithm, the prediction accuracies of the proposed models for the depth, width, material removal rate, and surface roughness reached 94.0%, 99.0%, 93.2%, and 91.2%, respectively. With the support of ELMSS and ELMPS, the results of the surface features can be predicted before machining and the appropriate process parameters can be selected in advance. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

17 pages, 16758 KiB

Open AccessArticle

Pulse Burst Generation and Diffraction with Spatial Light Modulators for Dynamic Ultrafast Laser Materials Processing

by Zheng Fang, Tong Zhou, Walter Perrie, Matthew Bilton, Jörg Schille, Udo Löschner, Stuart Edwardson and Geoff Dearden

Materials 2022, 15(24), 9059; https://doi.org/10.3390/ma15249059 - 18 Dec 2022

Cited by 4 | Viewed by 1803

Abstract

A pulse burst optical system has been developed, able to alter an energetic, ultrafast 10 ps, 5 kHz output pulse train to 323 MHz intra-burst frequency at the fundamental 5 kHz repetition rate. An optical delay line consisting of a beam-splitting polariser cube, [...] Read more.

A pulse burst optical system has been developed, able to alter an energetic, ultrafast 10 ps, 5 kHz output pulse train to 323 MHz intra-burst frequency at the fundamental 5 kHz repetition rate. An optical delay line consisting of a beam-splitting polariser cube, mirrors, and waveplates transforms a high-energy pulse into a pulse burst, circulating around the delay line. Interestingly, the reflected first pulse and subsequent pulses from the delay line have orthogonal linear polarisations. This fact allows independent modulation of these pulses using two-phase-only Spatial Light Modulators (SLM) when their directors are also aligned orthogonally. With hybrid Computer Generated Holograms (CGH) addressed to the SLMs, we demonstrate simultaneous multi-spot periodic surface micro-structuring on stainless steel with orthogonal linear polarisations and cylindrical vector (CV) beams with Radial and Azimuthal polarisations. Burst processing produces a major change in resulting surface texture due to plasma absorption on the nanosecond time scale; hence the ablation rates on stainless steel with pulse bursts are always lower than 5 kHz processing. By synchronising the scan motion and CGH application, we show simultaneous independent multi-beam real-time processing with pulse bursts having orthogonal linear polarisations. This novel technique extends the flexibility of parallel beam surface micro-structuring with adaptive optics. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

24 pages, 13575 KiB

Open AccessArticle

Experimental Research and Optimization of Ti-6Al-4V Alloy Microgroove Machining Based on Waterjet-Guided High-Power Laser

by Qian Liu, Yugang Zhao, Jianbing Meng, Zhilong Zheng, Chen Cao, Guoyong Zhao, Chuang Zhao, Guangxin Liu, Di Dai and Zhuang Song

Materials 2022, 15(21), 7430; https://doi.org/10.3390/ma15217430 - 23 Oct 2022

Cited by 5 | Viewed by 1038

Abstract

In order to improve the tribological properties of Ti-6Al-4V alloy and further broaden the application scope of titanium alloy materials in the industrial field, a preparation method of a waterjet-guided high-power laser processing surface microgroove was studied. In this paper, a multifocus coupling [...] Read more.

In order to improve the tribological properties of Ti-6Al-4V alloy and further broaden the application scope of titanium alloy materials in the industrial field, a preparation method of a waterjet-guided high-power laser processing surface microgroove was studied. In this paper, a multifocus coupling lens was innovatively designed to replace the spherical lens in the traditional waterjet-guided laser coupling device, which avoids the gas explosion phenomenon in the coupling of the high-power laser and waterjet, and realizes the high-quality coupling of the high-power laser and water beam fiber. Then, with the microgroove morphology as the response target, the single-factor test and response surface test of the water-guided laser processing microgroove were carried out. Based on the experimental results, an approximate mathematical model of the response surface between the process parameters and the microgroove topography target was constructed, and the quantitative relationship between the waterjet-guided laser processing parameters and the target response was studied. At the same time, the optimal combination of process parameters was obtained by multiobjective optimization, so as to effectively improve the microgroove morphology. This technology provides method guidance and a decision-making reference for subsequent waterjet-guided laser processing of titanium alloy surface functional microstructures. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

16 pages, 7116 KiB

Open AccessArticle

The Study on Resolution Factors of LPBF Technology for Manufacturing Superelastic NiTi Endodontic Files

by Stanislav V. Chernyshikhin, Ivan A. Pelevin, Farzad Karimi and Igor V. Shishkovsky

Materials 2022, 15(19), 6556; https://doi.org/10.3390/ma15196556 - 21 Sep 2022

Cited by 9 | Viewed by 2126

Abstract

Laser Powder Bed Fusion (LPBF) technology is a new trend in manufacturing complex geometric structures from metals. This technology allows producing topologically optimized parts for aerospace, medical and industrial sectors where a high performance-to-weight ratio is required. Commonly the feature size for such [...] Read more.

Laser Powder Bed Fusion (LPBF) technology is a new trend in manufacturing complex geometric structures from metals. This technology allows producing topologically optimized parts for aerospace, medical and industrial sectors where a high performance-to-weight ratio is required. Commonly the feature size for such applications is higher than 300–400 microns. However, for several possible applications of LPBF technology, for example, microfluidic devices, stents for coronary vessels, porous filters, dentistry, etc., a significant increase in the resolution is required. This work is aimed to study the resolution factors of LPBF technology for the manufacturing of superelastic instruments for endodontic treatment, namely Self-Adjusting Files (SAF). Samples of thin walls with different incline angles and SAF samples were manufactured from Nickel-Titanium pre-alloyed powder with a 15–45 μm fraction. The printing procedure was done using an LPBF set-up equipped with a conventional ytterbium fiber laser with a nominal laser spot diameter of 55 microns. The results reveal physical, apparatus, and software factors limiting the resolution of the LPBF technology. Additionally, XRD and DSC tests were done to study the effect of single track based scanning mode manufacturing on the phase composition and phase transformation temperatures. Found combination of optimal process parameters including laser power of 100 W, scanning speed of 850 mm/s, and layer thickness of 20 μm was suitable for manufacturing SAF files with the required resolution. The results will be helpful for the production of NiTi micro objects based on periodic structures both by the LPBF and μLPBF methods. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

8 pages, 2432 KiB

Open AccessArticle

Large-Area Fabrication of LIPSS for Wetting Control Using Multi-Parallel Femtosecond Laser Processing

by Simonas Indrišiūnas, Evaldas Svirplys and Mindaugas Gedvilas

Materials 2022, 15(16), 5534; https://doi.org/10.3390/ma15165534 - 11 Aug 2022

Cited by 9 | Viewed by 1451

Abstract

In this research, the wetting property control of a stainless-steel surface, structured using parallel processing via an array of 64-femtosecond laser beams, is presented. The scanning of an 8 × 8-beam array over the sample was used to uniformly cover the large areas [...] Read more.

In this research, the wetting property control of a stainless-steel surface, structured using parallel processing via an array of 64-femtosecond laser beams, is presented. The scanning of an 8 × 8-beam array over the sample was used to uniformly cover the large areas with LIPSS. The static water contact angle and the LIPSS period dependence on processing parameters were investigated. The wettability control of water droplets on laser-patterned stainless steel, ranging from contact angles of ~63°, similar to those of the plain surface, to the superhydrophobic surface with contact angles > 150°, was achieved. The relationship between the static water contact angle and the LIPSS parameters in the Fourier plane was investigated. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

15 pages, 3164 KiB

Open AccessArticle

Experimental Investigation on Process Parameters during Laser-Assisted Turning of SiC Ceramics Based on Orthogonal Method and Response Surface Methodology

by Di Dai, Yugang Zhao, Chen Cao, Ruichun Dong, Haiyun Zhang, Qian Liu, Zhuang Song, Xiajunyu Zhang, Zhilong Zheng and Chuang Zhao

Materials 2022, 15(14), 4889; https://doi.org/10.3390/ma15144889 - 14 Jul 2022

Cited by 10 | Viewed by 1432

Abstract

In this study, laser-assisted machining experiments are carried out on silicon carbide (SiC) ceramic materials by a turning process, and laser power, cutting depth, rotational speed, and feed speed are selected as research factors. In order to improve the surface processing quality of [...] Read more.

In this study, laser-assisted machining experiments are carried out on silicon carbide (SiC) ceramic materials by a turning process, and laser power, cutting depth, rotational speed, and feed speed are selected as research factors. In order to improve the surface processing quality of laser-assisted turning of SiC ceramics and obtain the smallest surface roughness, the orthogonal method and response surface method are used to investigate the effect of various factors on surface roughness. The effect of various factors on surface roughness is evaluated by variance analysis, mean analysis, main effect diagram, 3D response surface, and corresponding contour diagram. The surface roughness prediction model is established based on the response surface method, and the prediction error is 4.1% with high accuracy. The experimental results show that laser power and cutting depth are the most significant factors affecting surface roughness, and rotational speed is a significant factor affecting surface roughness. Under the optimum process conditions, the smallest surface roughness Ra obtained by the response surface method is 0.294 μm, which is lower than 0.315 μm obtained by the orthogonal method, and the surface quality is higher. Therefore, the optimal process parameters of the response surface method can obtain the smallest surface roughness and higher surface quality in laser-assisted turning of SiC ceramics. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

15 pages, 3975 KiB

Open AccessArticle

Fabrication and Optimisation of Ti-6Al-4V Lattice-Structured Total Shoulder Implants Using Laser Additive Manufacturing

by Oliver Bittredge, Hany Hassanin, Mahmoud Ahmed El-Sayed, Hossam Mohamed Eldessouky, Naser A. Alsaleh, Nashmi H. Alrasheedi, Khamis Essa and Mahmoud Ahmadein

Materials 2022, 15(9), 3095; https://doi.org/10.3390/ma15093095 - 25 Apr 2022

Cited by 20 | Viewed by 2512

Abstract

This work aimed to study one of the most important challenges in orthopaedic implantations, known as stress shielding of total shoulder implants. This problem arises from the elastic modulus mismatch between the implant and the surrounding tissue, and can result in bone resorption [...] Read more.

This work aimed to study one of the most important challenges in orthopaedic implantations, known as stress shielding of total shoulder implants. This problem arises from the elastic modulus mismatch between the implant and the surrounding tissue, and can result in bone resorption and implant loosening. This objective was addressed by designing and optimising a cellular-based lattice-structured implant to control the stiffness of a humeral implant stem used in shoulder implant applications. This study used a topology lattice-optimisation tool to create different cellular designs that filled the original design of a shoulder implant, and were further analysed using finite element analysis (FEA). A laser powder bed fusion technique was used to fabricate the Ti-6Al-4V test samples, and the obtained material properties were fed to the FEA model. The optimised cellular design was further fabricated using powder bed fusion, and a compression test was carried out to validate the FEA model. The yield strength, elastic modulus, and surface area/volume ratio of the optimised lattice structure, with a strut diameter of 1 mm, length of 5 mm, and 100% lattice percentage in the design space of the implant model were found to be 200 MPa, 5 GPa, and 3.71 mm⁻¹, respectively. The obtained properties indicated that the proposed cellular structure can be effectively applied in total shoulder-replacement surgeries. Ultimately, this approach should lead to improvements in patient mobility, as well as to reducing the need for revision surgeries due to implant loosening. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

19 pages, 5471 KiB

Open AccessArticle

Selective Laser Sintering of PA 2200 for Hip Implant Applications: Finite Element Analysis, Process Optimization, Morphological and Mechanical Characterization

by Răzvan Păcurar, Petru Berce, Anna Petrilak, Ovidiu Nemeş, Cristina Ştefana Miron Borzan, Marta Harničárová and Ancuţa Păcurar

Materials 2021, 14(15), 4240; https://doi.org/10.3390/ma14154240 - 29 Jul 2021

Cited by 11 | Viewed by 3039 | Correction

Abstract

Polyamide 12 (PA 22000) is a well-known material and one of the most biocompatible materials tested and used to manufacture customized medical implants by selective laser sintering technology. To optimize the implants, several research activities were considered, starting with the design and manufacture [...] Read more.

Polyamide 12 (PA 22000) is a well-known material and one of the most biocompatible materials tested and used to manufacture customized medical implants by selective laser sintering technology. To optimize the implants, several research activities were considered, starting with the design and manufacture of test samples made of PA 2200 by selective laser sintering (SLS) technology, with different processing parameters and part orientations. The obtained samples were subjected to compression tests and later to SEM analyses of the fractured zones, in which we determined the microstructural properties of the analyzed samples. Finally, an evaluation of the surface roughness of the material and the possibility of improving the surface roughness of the realized parts using finite element analysis to determine the optimum contact pressure between the component made of PA 2200 by SLS and the component made of TiAl6V4 by SLM was performed. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

11 pages, 5635 KiB

Open AccessArticle

Laser Powder Bed Fusion of Chromium Bronze Using Recycled Powder

by Ivan A. Pelevin, Maxim A. Burmistrov, Dmitriy Yu. Ozherelkov, Alexander S. Shinkaryov, Stanislav V. Chernyshikhin, Alexander A. Gromov and Anton Yu. Nalivaiko

Materials 2021, 14(13), 3644; https://doi.org/10.3390/ma14133644 - 30 Jun 2021

Cited by 4 | Viewed by 1783

Abstract

Laser powder bed fusion (LPBF) of Cu-0.5Cr was carried out using recycled powder taken out from the LPBF machine after previous printing. Various volumetric defects characterized the powder wherein particle size distribution was the same as virgin powder. Using recycled powder resulted in [...] Read more.

Laser powder bed fusion (LPBF) of Cu-0.5Cr was carried out using recycled powder taken out from the LPBF machine after previous printing. Various volumetric defects characterized the powder wherein particle size distribution was the same as virgin powder. Using recycled powder resulted in extra spherical pore formation after the LPBF process. Despite that, a relative density of 99.2% was achieved by LPBF parameters optimization. Solidified microstructure with a small volume of defects consisted of an oversaturated dendritic Cu matrix and nano-sized Cr precipitations providing strengthening mechanism occurrence. The possibility of a satisfactory level of mechanical properties with σ_0.2 = 136.8 MPa, UTS = 187.4 MPa, along with 15.5% of elongation achieving, was shown. Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

► Show Figures

Figure 1

Other

Jump to: Research

1 pages, 187 KiB

Open AccessCorrection

Correction: Răzvan et al. Selective Laser Sintering of PA 2200 for Hip Implant Applications: Finite Element Analysis, Process Optimization, Morphological and Mechanical Characterization. Materials 2021, 14, 4240

by Răzvan Păcurar, Petru Berce, Anna Petrilak, Ovidiu Nemeş, Cristina Ştefana Miron Borzan, Marta Harničárová and Ancuţa Păcurar

Materials 2022, 15(1), 132; https://doi.org/10.3390/ma15010132 - 24 Dec 2021

Viewed by 1503

Abstract

The authors wish to make the following correction to their paper [...] Full article

(This article belongs to the Special Issue Advanced Laser Microfabrication)

Journal Menu

Journal Browser

Advanced Laser Microfabrication

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (10 papers)

Research

Other

Further Information

Guidelines

MDPI Initiatives

Follow MDPI