Possible explanations for different surface quality in laser cutting with 1 and 10 μm beams

Hirano, Kōji; Fabbro, R.

doi:10.2351/1.3672477

Cited by 57 publications

(24 citation statements)

References 23 publications

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“…Summarizing the simulations, 15,30 experiments, 13,16 and articles combining experiments and theory, 31,32 the best speed-quality relationship is achieved when the melt front inclination angle provides absorbed energy supporting maximally uniform melt flow in all melt pool regions, with minimal melt accumulation. The relationship between the averaged melt front inclination angle, kerf geometry, and laser beam size governs the averaged fraction of the beam power involved in the cutting process.…”

Section: Laser Beam Shape Position and Distortionmentioning

confidence: 99%

“…The working hypothesis of the final kerf relief formation is solidification of the unstable melt flow. 13,14 Detailed investigations by Hirano and Fabbro 15,16 show that this instability is a sum of thermodynamic instability (related to the localized melting) and hydrodynamic instability (caused by the imbalance of assist gas flux and surface tension forces). The instability pattern varies along the melt flow, causing the complicated final relief of the kerf surface.…”

Section: Speed-power-pressure Conceptmentioning

confidence: 99%

“…Existing studies [7][8][9][10][11][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] do not consider the spatial characteristics of laser beams. Nevertheless, these are accounted for by the FPP, which is one of the key factors of the cutting process.…”

Section: Laser Beam Shape Position and Distortionmentioning

confidence: 99%

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Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Yurevich

Grimm

Polyakov³

et al. 2015

Opt. Eng

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Abstract. We analyzed the effects of the focal point aberrational offset in optical transport systems for highpower lasers. Transverse and near-axial laser intensity distribution transformations in the presence of both positive and negative spherical aberrations were numerically calculated and experimentally demonstrated for different strengths. We show that spherical aberration yields considerable asymmetry of the focused beam's caustic. Several optical transport systems with identical optical parameters (excluding the noncorrected axial beam spherical aberration) were designed. We examined the effects of the laser intensity profiles produced by these systems on the quality of oxygen-assisted laser cutting of medium-section mild steel. We show that high-quality cuts can be obtained for different shapes of laser intensity distribution. However, the greater the refocusing magnitude introduced by the spherical aberration correction, the more precisely the focal point position must be maintained during the laser cutting process. © The Authors. Published by SPIE under a Creative Commons 1 Introduction Laser cutting of metals and alloys is one of the most commercially valuable laser technology processes. Originating from basic research on laser-matter interaction, 1 the field has significantly developed, now offering a large arsenal of state-of-the-art techniques.2-5 Omitting the energy and resource efficiency issues, 6 the performance of laser cutting can be captured by only two output parameters. These are the cutting speed and kerf quality. Thus, laser cutting optimization reduces to achieving the maximal cutting speed with the best kerf quality. As far as the material separation is concerned, 7 the speed can be dramatically increased. On the other hand, the cutting quality depends on many parameters. The most important and frequently discussed are the kerf geometry (accuracy, width, and taper), the surface quality (cut-edge roughness, striations morphology, and dross and burr inclusions), and the mechanical and metallurgical properties (hardness and strength, heat-affected zone, and oxide layer). 8 The number of parameters dramatically affecting the cutting quality ranges from 25 9 to 75. 4,5 These are nearly evenly divided between the workpiece properties, assist gas parameters, laser machine, and laser beam characteristics. Input-output parameters relationships are mostly nonlinear and exhibit strong interdependence. In this regard, maximal precision is provided by the studies that focus on only one input-output parameter pair. Yet, this "one parameter at one time" approach does not provide complete information on the process as a whole.

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Section: Laser Beam Shape Position and Distortionmentioning

confidence: 99%

Section: Speed-power-pressure Conceptmentioning

confidence: 99%

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Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Yurevich

Grimm

Polyakov³

et al. 2015

Opt. Eng

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“…In the fiber laser case, this angle is bigger [8]. Under study are the physical mechanisms, for example in [9,10], which are responsible for the forming cut surface and higher surface nonuniformity in the fiber laser case, but it is still not clear by now. The spatial characteristics of the beams of both lasers differ, too: the intensity distribution in the beam cross section features more "sharp" edges for the fiber laser [9].…”

Section: Introductionmentioning

confidence: 99%

“…The method of roughness reduction at the fiber laser cutting is proposed in [10]; the concept is not to remove the causes of inhomogeneities, but to reduce and smooth occurred inhomogeneities. The way is to provide better heating of the side walls of the cut channel.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the effect of the laser beam polarization state on the quality of steel sheet cutting

Голышев

Orishich

Shulyatyev

2017

AIP Conference Proceedings

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Abstract. The paper presents the results of experimental investigation of the effect of the beam polarization on the quality of the oxygen-assisted laser cutting of steel by a СО 2 -laser. Under consideration is the effect of the laser cutting parameters by the beam with the linear polarization on the cut surface roughness. It is founded that the minimal roughness is reached when the electric field vector is perpendicular to the cutting speed vector. It is concluded that the absorbed power distribution imposes the essential influence on the surface quality, and that the radiation heating of side walls is important to have lower roughness. Obtained results enabled to present probable reasons of the worse surface quality of the metals cut by a fiber laser than the ones cut by a СО 2 -laser.

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Analysis and optimal control for free melt flow boundaries in laser cutting with distributed radiation

Vossen

Hermanns

Schüttler³

2013

Z Angew Math Mech

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This work introduces a mathematical model for laser cutting taking account of spatially distributed laser radiation. The model involves two coupled nonlinear partial differential equations describing the interacting dynamical behaviors of the free boundaries of the melt during the process. The model will be investigated by linear stability analysis to study the occurence of ripple formations at the cutting surface. We define a measurement for the roughness of the cutting surface and introduce an optimal control problem for minimizing the roughness with respect to the laser beam intensity along the free melt surface. Necessary optimality conditions will be deduced. Finally, a numerical solution will be presented and discussed by means of the necessary conditions. physical considerations

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Possible explanations for different surface quality in laser cutting with 1 and 10 μm beams

Cited by 57 publications

References 23 publications

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Gas-assisted laser cutting of medium-section metals using spherically aberrated beams

Experimental investigation of the effect of the laser beam polarization state on the quality of steel sheet cutting

Analysis and optimal control for free melt flow boundaries in laser cutting with distributed radiation

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