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Multi Response Optimization of Nd:YAG Laser Micro Drilling Characteristics of 304 Stainless Steel using Desirability Function Approach
摘要： Laser micro drilling is a non-traditional machining process for producing micro hole of various sizes and different angle in many modern industrial application, such as aerospace gas turbine, automobile industry, electronics field etc. Laser drilling is extremely high speed with high aspect ratio. However, the quality and accuracy of the holes can be excellent, if the optimal process parameter has set. It is difficult to achieve exact size of hole as per suggested by the equipment manufacturer without any consideration. So this paper addressed to investigate influence of process parameter on drilling characteristics of 304 stainless steel of 1.5 mm thickness material using Nd:YAG laser drilling through desirability function optimization technique. The effect of process parameter taken during machining operation is average power, nozzle stand-off, nitrogen gas pressure to obtain requisite hole quality. The output responses are entry circularity, exit circularity and taper angle were considered performance criteria for the experimentation. Analysis of variance (ANOVA) has been performed to find out the significant process parameter during the micro drilling process. It is found that nitrogen gas pressure is highly influencing factor on the overall response characteristics, which is about 54.62% and nozzle standoff is 2nd highest influencing parameter, which is about 27.69%.
关键词： 304 Stainless Steel,Laser Drilling Machine,Optimization,Desirability,ANOVA
更新于2025-09-16 10:30:52
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Percussion Drilling Hole in Cu, Al, Ti and Ni Alloys Using Ultra-Short Pulsed Laser Ablation
摘要： Comparative study on micro-deep hole drilling by picosecond ultra-short pulse laser in four metals, including copper, aluminum alloy, titanium alloy, and nickel alloy, was presented. Destructive testing was performed to measure the depth, shape, and side-wall morphology of micro-deep holes in this study. Diameters and depths of micro-deep holes in four metals ablated using the same processing parameters were compared. The multiple thresholds of metals had been calculated. Relationships between hole dimensions and multiple thresholds (the average ablation threshold, the ablation threshold and the thermal threshold) and physical properties (for example, the heat capacity, the melting temperature, the optical penetration depth and the absorbance, etc.) of the four metals are examined. Furthermore, the surface and side-wall morphologies of the micro-deep holes in four metals were demonstrated. The in?uence mechanisms, especially the side-wall morphology, were discussed, such as the thresholds, conical emission, self-cleaning e?ect, physical properties of metals, the energy transmission, the plasma e?ect, thermochemical reaction, and so on.
关键词： micro-deep hole,metals,ultrashort pulsed laser,percussion drilling
更新于2025-09-16 10:30:52
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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Fibre laser trepanning drilling of metals and alloys
摘要： Laser drilling of metals and alloys is extensively used in modern manufacturing industries to produce holes of various sizes and shapes. Currently, most aerospace laser drilling is performed using Nd:YAG laser and over the years many attempts have been made to increase the productivity of Nd:YAG lasers drilling process, but with little success. This paper investigates the use of recently developed millisecond-pulsed-Quasi-CW-fibre-laser for trepanning drilling of aerospace grade nickel super-alloy. The main investigation concentrates on understanding the effects of Quasi-CW-fibre-laser parameters on trepanning laser drilled hole quality. The principal findings are based on reducing the recast and oxide layer. Results show that the high average power of the Quasi-CW-fibre-lasers can be effectively used to achieve increased trepanning drilling speed without undermining the drilling quality, which is not feasible with a free-space Nd:YAG laser. Low peak power and high average power can be effectively used to produce better laser drilled hole than the high peak power and low frequency, which is observed with the traditional millisecond Nd:YAG drilling process.
关键词： alloys,Fibre laser,nickel super-alloy,trepanning drilling,oxide layer,aerospace,recast layer,metals
更新于2025-09-16 10:30:52
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Swirling Gas Jet-Assisted Laser Trepanning for a Galvanometer-Scanned CO2 Laser
摘要： Laser-drilled hole arrays are part of an important field that aim to improve efficiency without affecting the quality of laser-drilled holes. In this paper, a swirling gas jet was implemented to assist with laser trepanning for a galvanometer scanned CO2 laser. The proposed swirling gas jet is based on laser trepanning. This swirling gas jet nozzle was composed of four inlet tubes to produce the flow of the vortex. Then, the plume particles were excluded, and spatter on the surface of the workpiece decreased. Thus, this approach can mitigate the problem of overcooling. This study manipulated the appropriate parameter settings, which were simulated by computational fluid dynamics software ANSYS CFX. The proposed swirling gas jet can be used with galvanometer-based scanner systems to keep the laser beam from interference by spatter. In addition, a hollow position of the vortex was achieved by using the four inlet tubes, which resulted in pressure asymmetry in the nozzle and velocity distribution on the surface of the workpiece. The experiment verified that the depth of processing could be enhanced by 110% when trepanning at a scanning speed of 30 mm/s, and that the removal of volume could be enhanced by 71% in trepanning at a diameter of 1 mm by using a swirl assistant compared with a non-assisted condition. Furthermore, the material removal rate of the swirling jet increases when the machining area of the galvanometer-based scanner is larger.
关键词： laser trepanning,laser drilling,swirling gas jet,galvanometer-based scanner systems
更新于2025-09-16 10:30:52
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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Ultrafast laser trepanning process and modeling
摘要： We present an engineering model of ultrafast laser ablation with normal or non-normal (oblique) laser beams. It can be applied to trepanning drilling but also to zero-taper cutting. Specific experiments on line ablation are presented to understand how oblique beams can control the walls conicity. Industrial strategies for processing with high throughput and high quality are considered.
关键词： ultrafast laser,industrial processing,oblique beams,ablation,zero-taper cutting,trepanning drilling
更新于2025-09-16 10:30:52
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[IEEE 2019 International Wafer Level Packaging Conference (IWLPC) - San Jose, CA, USA (2019.10.22-2019.10.24)] 2019 International Wafer Level Packaging Conference (IWLPC) - Recent Breakthroughs in Tight Pitch Laser Microdrilling for Mems Guide Plates
摘要： Laser drilling of guide plates for Advanced Vertical Probecards has become a key enabling technology over the past several years. Amongst the key drivers is the switch in demand from circular shaped holes, achievable with both mechanical and laser drilling methods, to rectangular holes for MEMs style probes. These rectangular holes can only readily be produced with the use of laser technology. As semiconductor technology and wafer test advances, an additional driver is high density hole drilling, i.e. the ability to place smaller and smaller holes on tighter and tighter pitches, whilst keeping the material between adjacent holes intact. Typically, the 3D shaped profile of laser drilled holes cannot easily be controlled, with so called “entry rounding” and “taper angle” characteristics restricting tighter hole positioning. The challenge is therefore to develop new processes which essentially eliminate both entry rounding and taper to values of virtually zero. After a recent breakthrough this has now been achieved.
关键词： Laser drilling,guide plates,probe cards
更新于2025-09-16 10:30:52
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On the Effect of Part Orientation on Stress Distribution in AlSi10Mg Specimens Fabricated by Laser Powder Bed Fusion (L-PBF)
摘要： The freedom of design of AM products suffers from some limitations in case of powder bed metal processes, because AM part’s integrity is affected by the residual stress state that is a consequence of the thermal history during part fabrication. Aim of this work is to evaluate the effect of part orientation on stress distribution. Thus, flat samples of AlSi10Mg alloy built along different orientations are produced by means of laser powder bed fusion (L-PBF) process, also known as Selective Laser Melting (SLM). Then, the semi-destructive hole-drilling method is used to evaluate residual stresses beneath the surfaces of samples. The outcomes of the study can be exploited to define design rules in order to both minimize support structures and optimize the orientation of the part in the building volume.
关键词： Powder bed fusion,Residual stresses,Hole-drilling method,AlSi10Mg,Orientation
更新于2025-09-16 10:30:52
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Laser micro drilling methods for perforation of aircraft suction surfaces
摘要： To reduce the fuel consumption of large passenger aircrafts the hybrid laminar flow control is a key technology. For drag reduction, several millions of holes with diameters around 50 μm at the leading edges are needed. In this paper, the perforation of such titanium sheets using the laser processes of single pulse and percussion drilling is presented. The single pulse technique is an “on-the-fly” drilling process using a pulsed fibre laser in combination with a drilling optic with coaxial gas supply. The percussion technique is a flexible drilling process using a q-switched fibre laser combined with a galvanic scanner.
关键词： percussion,micro-holes,single pulse,HLFC structures,laser drilling
更新于2025-09-16 10:30:52
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Experimental Investigation on the Spatial-temporal Evolution of the hole formation during Laser Helical Drilling
摘要： In order to study the influence of process parameters of femtosecond laser helical machining on the formation of micro-holes, we selected main parameters of the femtosecond laser helical drilling process, used 304 stainless steel as the target material, designed a 5-factor and 5-level orthogonal experiment based on the orthogonal table, and analyzed the significance levels of the impacts of single pulse energy, repetition rate, rotation rate, rate of focus downward movement, and air-blowing pressure on the ablation depth. Based on back propagation (BP) neural network, we established the relationship model between five factors and the material ablation depth, and trained the network with orthogonal experiment data. We used the data of the additional drilling experiments to test the generalization ability of the established network, and the results show that the prediction error of the model is within 3%. We designed a single-factor experiment for the characteristic parameter of the helical drilling--the rate of focus downward movement--and obtained the effect of the rate of focus downward movement on the formation of the micro-holes during the process of femtosecond laser helical drilling.
关键词： femtosecond laser,ablation depth,helical drilling,micro-holes,BP neural network
更新于2025-09-16 10:30:52
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Study on nonthermala??thermal processing boundary in drilling of ceramics using ultrashort pulse laser system with variable parameters over a wide range
摘要： Quality and throughput of laser material processing are influenced by multiple laser parameters as well as material properties. Since material degradation due to laser processing is generally related to heat-affected zone, quick optimization and realization of nonthermal process is one of the most important issues for higher-grade laser processing. In this work, we developed various parameter-controlled ultrashort pulse laser system that can control various laser parameters over a wide range, such as pulse duration over three orders of magnitude. Using this laser system (wavelength: 1033 nm, pulse duration: 0.4 to 400 ps, repetition: up to 1 MHz), we have investigated nonthermal–thermal processing boundary in drilling of ceramics: aluminum nitride (AlN) and yttria-stabilized zirconia (YSZ), with high and low thermal conductivity, respectively. As a result, the AlN ceramic exhibited strong dependence of ablation rate on fluence: low-, mid- and high-fluence regimes appeared with different logarithmic correlations. Further, the nonthermal–thermal process boundaries appeared, depending on the pulse duration. On the other hand, the ablation behavior of YSZ was much different from AlN; the ablation rate did not show distinct three regimes. Further, there were no nonthermal process windows for the YSZ. Therefore, the nonthermal–thermal process boundaries were governed by the laser parameters like pulse duration as well as the material thermal conductivity.
关键词： Ultrashort pulse laser,Ceramics,Drilling
更新于2025-09-16 10:30:52