start-ver=1.4 cd-journal=joma no-vol=68 cd-vols= no-issue=1 article-no= start-page=197 end-page=200 dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20191231 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=High surface quality micro machining of monocrystalline diamond by picosecond pulsed laser en-subtitle= kn-subtitle= en-abstract= kn-abstract=In micro machining of monocrystalline diamond by pulsed laser, unique processing characteristics appeared only under a few ten picosecond pulse duration and a certain overlap rate of laser shot. Cracks mostly propagate in parallel direction to top surface of workpiece, although the laser beam axis is perpendicular to the surface. This processed area can keep diamond structure, and its surface roughness is smaller than R-a = 0.2 mu M. New laser micro machining method to keep diamond structure and small surface roughness is proposed. This method can contribute to reduce the polishing process in micro machining of diamond. (C) 2019 Published by Elsevier Ltd on behalf of CIRP. en-copyright= kn-copyright= en-aut-name=OkamotoY. en-aut-sei=Okamoto en-aut-mei=Y. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OkadaA. en-aut-sei=Okada en-aut-mei=A. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KajitaniA. en-aut-sei=Kajitani en-aut-mei=A. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=ShinonagaT. en-aut-sei=Shinonaga en-aut-mei=T. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Natural Science & Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science & Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science & Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Natural Science & Technology, Okayama University kn-affil= en-keyword=Laser beam machining (LBM) kn-keyword=Laser beam machining (LBM) en-keyword=Laser micro machining kn-keyword=Laser micro machining en-keyword=Diamond kn-keyword=Diamond END start-ver=1.4 cd-journal=joma no-vol=9 cd-vols= no-issue=7 article-no= start-page=1412 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20190303 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Influence of Numerical Aperture on Molten Area Formation in Fusion Micro-Welding of Glass by Picosecond Pulsed Laser en-subtitle= kn-subtitle= en-abstract= kn-abstract= Focusing condition such as numerical aperture (N.A.) has a great influence on the creation of molten area and the stable welding process in fusion micro-welding of glass. In this study, a picosecond pulsed laser of 1064 nm in wavelength and 12.5 ps in pulse duration was tightly focused inside a borosilicate glass using objective lenses of numerical apertures 0.45, 0.65, and 0.85 with spherical aberration correction. Influence of numerical aperture on molten area formation was experimentally investigated through analysis of focusing situation in glass, and movement of absorption point, and then molten area characteristics were discussed. It is concluded that N.A. of 0.65 with superior focusing characteristics can form a large and continuous molten area without cracks, which enables achievement of stable joining of glass material by picosecond pulsed laser. en-copyright= kn-copyright= en-aut-name=OuyangZhiyong en-aut-sei=Ouyang en-aut-mei=Zhiyong kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OkamotoYasuhiro en-aut-sei=Okamoto en-aut-mei=Yasuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OginoYuta en-aut-sei=Ogino en-aut-mei=Yuta kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SakagawaTomokazu en-aut-sei=Sakagawa en-aut-mei=Tomokazu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=OkadaAkira en-aut-sei=Okada en-aut-mei=Akira kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil= kn-affil= affil-num=5 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=ultrashort pulsed laser kn-keyword=ultrashort pulsed laser en-keyword=glass material kn-keyword=glass material en-keyword=absorption point kn-keyword=absorption point en-keyword=molten area kn-keyword=molten area en-keyword=numerical aperture kn-keyword=numerical aperture END start-ver=1.4 cd-journal=joma no-vol=64 cd-vols= no-issue=6 article-no= start-page=937 end-page=947 dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=20200313 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Effect of numerical aperture on molten area characteristics in micro-joining of glass by picosecond pulsed laser en-subtitle= kn-subtitle= en-abstract= kn-abstract=Glass products with precise and sophisticated shapes are highly demanded in the field of MEMS due to their excellent properties. Ultrashort pulsed laser has been expected to be a powerful and reliable tool for micro-welding of glass. Focusing condition such as numerical aperture (N.A.) is a critical parameter that controls how ultrashort laser pulses interact with and propagate in glass, and it has a great influence on the laser micro-welding characteristics of glass. In order to investigate the quality of welding process, it is important to understand the dependence of the mechanical strength of molten area created in glass specimen with various numerical apertures. Therefore, the mechanical strength of molten area with various numerical apertures was evaluated in micro-welding of glass by picosecond pulsed laser. Higher bending strength could be obtained under an appropriate volume ratio of molten area and glass specimen, when continuous molten areas were formed. In addition, high density and large size of molten area without crack led to higher breaking stress. It is concluded that superior focusing characteristics such as N.A. 0.65 enable a long region of high power density in beam axis, which can satisfy both high mechanical strength and high processing speed. en-copyright= kn-copyright= en-aut-name=OkamotoYasuhiro en-aut-sei=Okamoto en-aut-mei=Yasuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OuyangZhiyong en-aut-sei=Ouyang en-aut-mei=Zhiyong kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=FujiwaraTakumi en-aut-sei=Fujiwara en-aut-mei=Takumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=OkadaAkira en-aut-sei=Okada en-aut-mei=Akira kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=Picosecond pulsed laser kn-keyword=Picosecond pulsed laser en-keyword=Glass material kn-keyword=Glass material en-keyword=Numerical aperture kn-keyword=Numerical aperture en-keyword=Bending strength kn-keyword=Bending strength en-keyword=Breaking stress kn-keyword=Breaking stress END start-ver=1.4 cd-journal=joma no-vol=299 cd-vols= no-issue= article-no= start-page=117388 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=20210930 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Effects of Superposition of 532?nm and 1064?nm Wavelengths in Copper Micro-welding by Pulsed Nd:YAG Laser en-subtitle= kn-subtitle= en-abstract= kn-abstract=Unstable and low absorption of laser energy is experienced in copper welding at around 1000?nm wavelength. At 532?nm wavelength, there is stable and high laser absorption by copper. Past researches have shown that transitional processing condition between keyhole and heat conduction welding results in a stable micro-welding process characterized by good surface quality and deep penetration. In order to adapt laser welding to copper using pulsed Nd:YAG lasers, investigations of welding quality and efficiency were addressed. Processing was done under transitional processing condition between heat conduction and keyhole welding. Copper C1020 specimens were processed using superposed laser wavelengths of 1064?nm and 532?nm. Effects of irradiation delay and power density on the process were clarified by taking measurements of absorption rates and molten volumes, and by analyzing the weld beads. In addition, the dynamics of molten area and keyhole formation were investigated through three-dimensional FEM analysis. A stabilized laser absorption and increased molten volume was achieved by superposition using 532?nm laser of an appropriate high power density coupled with a short irradiation delay for the 1064?nm laser, which resulted in high-efficiency welding of copper. en-copyright= kn-copyright= en-aut-name=MainaMartin Ruthandi en-aut-sei=Maina en-aut-mei=Martin Ruthandi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OkamotoYasuhiro en-aut-sei=Okamoto en-aut-mei=Yasuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HamadaKazuki en-aut-sei=Hamada en-aut-mei=Kazuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=OkadaAkira en-aut-sei=Okada en-aut-mei=Akira kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=NakashibaShin-ichi en-aut-sei=Nakashiba en-aut-mei=Shin-ichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=NishiNorio en-aut-sei=Nishi en-aut-mei=Norio kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=Nontraditional Machining Laboratory, Okayama University kn-affil= affil-num=2 en-affil=Nontraditional Machining Laboratory, Okayama University kn-affil= affil-num=3 en-affil=Nontraditional Machining Laboratory, Okayama University kn-affil= affil-num=4 en-affil=Nontraditional Machining Laboratory, Okayama University kn-affil= affil-num=5 en-affil=Kataoka Corporation kn-affil= affil-num=6 en-affil=Kataoka Corporation kn-affil= END start-ver=1.4 cd-journal=joma no-vol=16 cd-vols= no-issue=2 article-no= start-page=109 end-page=114 dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=202110 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Formation and Its Mechanism of High-speed Micro-grooving on Metal Surface by Angled CW Laser Irradiation en-subtitle= kn-subtitle= en-abstract= kn-abstract=In general, pulsed lasers with high peak power have been used for the micro-groove formation. However, the processing speed is limited by the pulse repetition rate. On the other hand, CW laser can be expected to perform the high-speed processing by continuous energy input. The mechanism of micro-groove formation by CW laser was investigated by high-speed observation and the thermal fluid analysis. In the perpendicular irradiation of CW laser, the molten metal flows symmetrically around the keyhole to the backward direction, and micro-grooves remain at both edges of molten region. In contrast, in the angled irradiation, the molten metal at the reflection-side scatters as spatters. The remained molten metal flows from the reflection-side to the incident-side through the bottom of keyhole, since the recoil pressure is generated from the reflection-side to the incident-side. In addition, high-speed scanning contributes to keeping the sufficient time and force to move the molten metal in the backward direction. Then, the micro-groove remains at the reflection-side, while the upheaval is formed at the incident-side by gathering the molten metal from the reflection-side and the front of keyhole. Asymmetrical behavior of molten metal flow in angled irradiation of CW laser can create micro-groove in the reflection-side. en-copyright= kn-copyright= en-aut-name=TauraNozomi en-aut-sei=Taura en-aut-mei=Nozomi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MitsunobuAkiya en-aut-sei=Mitsunobu en-aut-mei=Akiya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=SakaiTatsuhiko en-aut-sei=Sakai en-aut-mei=Tatsuhiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=OkamotoYasuhiro en-aut-sei=Okamoto en-aut-mei=Yasuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=OkadaAkira en-aut-sei=Okada en-aut-mei=Akira kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University, Japan kn-affil= affil-num=2 en-affil=Faculty of Engineering, Okayama University, Japan kn-affil= affil-num=3 en-affil=NIPPON STEEL CORPORATION, Japan kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University, Japan kn-affil= affil-num=5 en-affil=Graduate School of Natural Science and Technology, Okayama University, Japan kn-affil= en-keyword=CW laser kn-keyword=CW laser en-keyword=micro-groove kn-keyword=micro-groove en-keyword=high-speed scanning kn-keyword=high-speed scanning en-keyword=thermal fluid analysis kn-keyword=thermal fluid analysis en-keyword=high-speed observation kn-keyword=high-speed observation END start-ver=1.4 cd-journal=joma no-vol=4 cd-vols= no-issue=2 article-no= start-page=025301 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20220317 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=High-quality micro-shape fabrication of monocrystalline diamond by nanosecond pulsed laser and acid cleaning en-subtitle= kn-subtitle= en-abstract= kn-abstract=The flat plane of small surface roughness below 0.1 mu m average roughness was obtained for monocrystalline diamond by nanosecond pulsed laser irradiation of 1060 nm and post-process acid cleaning, at a laser fluence around the material removal threshold value. The glossy and flat plane at the bottom of the micro-groove was parallel to the top surface of the specimen, although the round beam of Gaussian mode was irradiated in the direction perpendicular to the top surface of specimen. The square beam of top-hat mode produced a shallower micro-groove with a wider, flatter bottom compared with the round beam in Gaussian mode. The creation method of the flat plane with small surface roughness was discussed in the arrangement strategy of linear micro-grooving by the square beam of top-hat mode. Normal side-by-side repetition of linear micro-grooving did not create a flat plane with constant depth. Therefore, a two-step scanning method was proposed in order to overcome the problem in the normal side-by-side repetition of liner micro-grooving. Non-removal areas were partly retained between the processing lines in the first step, and the laser scanning was conducted on the retained area in the second step. The newly proposed two-step scanning method was practical and useful to create a widely flat plane with small surface roughness, and the two-step scanning method provided superior control over the micro-groove depth. This proposed method can reduce the surface roughness in addition to the shape creation of monocrystalline diamond, and it can be used as a high-quality micro-shape fabrication method of monocrystalline diamond. en-copyright= kn-copyright= en-aut-name=OkamotoYasuhiro en-aut-sei=Okamoto en-aut-mei=Yasuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=OkuboTubasa en-aut-sei=Okubo en-aut-mei=Tubasa kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KajitaniAtsuya en-aut-sei=Kajitani en-aut-mei=Atsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=OkadaAkira en-aut-sei=Okada en-aut-mei=Akira kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=monocrystalline diamond kn-keyword=monocrystalline diamond en-keyword=nanosecond pulsed laser kn-keyword=nanosecond pulsed laser en-keyword=flat surface kn-keyword=flat surface en-keyword=smooth surface kn-keyword=smooth surface en-keyword=micro-grooving kn-keyword=micro-grooving END start-ver=1.4 cd-journal=joma no-vol=35 cd-vols= no-issue=1-2 article-no= start-page=21 end-page=28 dt-received= dt-revised= dt-accepted= dt-pub-year=2001 dt-pub=20010327 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Laser Welding of Slices of Magnetic Circuit en-subtitle= kn-subtitle= en-abstract= kn-abstract=In electric power industry, there is a problem of achieving stable joint in different components using high productive and efficient technologies. One type of these components is packages of slices for magnetic circuit of electric motors, transformers etc., which need reliable means for their fixing. Laser welding is proposed to solve this problem as an alternative for existing technologies. The development of the laser welding process is presented based on process simulation, study of heat history and comparison with experimental results. Laser beam additional scanning technique is proposed to improve the quality and efficiency of the joining operation. en-copyright= kn-copyright= en-aut-name=S.kovalenkoVolodymyr en-aut-sei=S.kovalenko en-aut-mei=Volodymyr kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=UnoYoshiyuki en-aut-sei=Uno en-aut-mei=Yoshiyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OkamotoYasuhiro en-aut-sei=Okamoto en-aut-mei=Yasuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=AnyakinM. en-aut-sei=Anyakin en-aut-mei=M. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=LutayA. en-aut-sei=Lutay en-aut-mei=A. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=ShubulKhaled Al. en-aut-sei=Shubul en-aut-mei=Khaled Al. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil= kn-affil=Department of Mechanical Engineering (Now at Laser Technology Research Institute, National Technical affil-num=2 en-affil= kn-affil=Department of Mechanical Engineering affil-num=3 en-affil= kn-affil=Department of Mechanical Engineering affil-num=4 en-affil= kn-affil=Laser Technology Research Institute, National Technical University of Ukraine affil-num=5 en-affil= kn-affil=Laser Technology Research Institute, National Technical University of Ukraine affil-num=6 en-affil= kn-affil=Laser Technology Research Institute, National Technical University of Ukraine END start-ver=1.4 cd-journal=joma no-vol=67 cd-vols= no-issue=8 article-no= start-page=1997 end-page=2005 dt-received= dt-revised= dt-accepted= dt-pub-year=2023 dt-pub=20230608 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Study on joint characteristics in laser butt welding of AMed and wrought Ti6Al4V plates en-subtitle= kn-subtitle= en-abstract= kn-abstract=Titanium alloy Ti6Al4V has been widely applied to medical, automotive, and aerospace industries due to its excellent properties such as high strength and excellent corrosion resistance. On the other hand, additive manufacturing (AM) technology can give the freedom of design of the products. In order to spread the AMed products, the joining of AMed and wrought products are required, and it is important to understand the joint characteristics. In this study, butt welding of Ti6Al4V plate was conducted by fiber laser in argon shielding, and the joint characteristics of laser weld wrought/wrought, AMed/AMed, and AMed/wrought Ti6Al4V plates were experimentally investigated. The AMed plate has higher tensile strength than wrought plate but the elongation of AMed plate is smaller, since AMed plate has f martensite due to rapid cooling during laser irradiation in AM process. Then, the laser weld joint of AMed/AMed plates has higher tensile strength, but smaller elongation than that of wrought/wrought plates. The weld joint of AMed/wrought plates shows good welding state, since small heat input leads to formation of small weld bead with higher hardness between wrought and AMed plates. en-copyright= kn-copyright= en-aut-name=OkamotoYasuhiro en-aut-sei=Okamoto en-aut-mei=Yasuhiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=ShinonagaTogo en-aut-sei=Shinonaga en-aut-mei=Togo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TakemotoYoshito en-aut-sei=Takemoto en-aut-mei=Yoshito kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=OkadaAkira en-aut-sei=Okada en-aut-mei=Akira kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=OchiAkihiro en-aut-sei=Ochi en-aut-mei=Akihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=KishimotoRyuya en-aut-sei=Kishimoto en-aut-mei=Ryuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=PityanaSisa en-aut-sei=Pityana en-aut-mei=Sisa kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=ArthurNana en-aut-sei=Arthur en-aut-mei=Nana kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=OmoniyiPeter en-aut-sei=Omoniyi en-aut-mei=Peter kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=MahamoodRasheedat en-aut-sei=Mahamood en-aut-mei=Rasheedat kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=MainaMartin en-aut-sei=Maina en-aut-mei=Martin kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=AkinlabiEsther en-aut-sei=Akinlabi en-aut-mei=Esther kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= affil-num=1 en-affil=Okayama University kn-affil= affil-num=2 en-affil=Okayama University kn-affil= affil-num=3 en-affil=Okayama University kn-affil= affil-num=4 en-affil=Okayama University kn-affil= affil-num=5 en-affil=Okayama University kn-affil= affil-num=6 en-affil=Okayama University kn-affil= affil-num=7 en-affil=National Laser Centre, CSIR kn-affil= affil-num=8 en-affil=National Laser Centre, CSIR kn-affil= affil-num=9 en-affil=University of Johannesburg kn-affil= affil-num=10 en-affil=University of Johannesburg kn-affil= affil-num=11 en-affil=Jomo Kenyatta University of Agriculture and Technology kn-affil= affil-num=12 en-affil=University of Johannesburg kn-affil= en-keyword=Ti6Al4V kn-keyword=Ti6Al4V en-keyword=Joint characteristics kn-keyword=Joint characteristics en-keyword=Laser welding kn-keyword=Laser welding en-keyword=Butt welding kn-keyword=Butt welding en-keyword=Additive manufacturing kn-keyword=Additive manufacturing END