The role of oxygen purity in laser cutting of mild steel

Powell, John; Ivarson, Anders; Kamalu, John; Brodén, G.; Magnusson, Claes

doi:10.2351/1.5058516

Cited by 21 publications

(13 citation statements)

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“…The surface quality problem is closely related to the melt removal process and for oxygen cutting to side burning problems as well. 4,5 Basic features that deteriorate cutting quality are surface roughness, that of a striated shape, and dross ͑resolidi-fied material on the rear surface͒. For inert assist gas, laser cutting surface quality was observed to depend strongly on the gas flow parameters.…”

Section: Introductionmentioning

confidence: 96%

Visualization of events inside kerfs during laser cutting of fusible metal

Yudin

Ковалев

2009

Journal of Laser Applications

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The subject of the research is mechanism of melt removal and striated roughness generation. Being the main obstacle limiting laser cutting process performance, these phenomena are widely discussed. Available theoretical descriptions are not conclusive, as they have nothing to be verified with. High temperatures and narrowness of the kerf severely limit visual access at a real facility. Observation will become possible if one wall of the kerf is made of glass. This possibility is utilized in present experiments, which reproduce the process at low temperatures. Rose’s alloy (melting at 96 °C) is cut by reduced power laser beam (below 300 W) and high-speed photographic recordings are done. The experiments are carried out for thick materials (10 and 20 mm) under cut. Examination of the video data brought out innovative views on the melt removal. The cutting front was noted to be upright. The striation structure was observed to be generated at a certain distance from the cutting front and without direct assistance of laser radiation. Adequacy of the model experiment to the real case was confirmed by direct comparison of surfaces and by analysis of similarity relations.

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Section: Introductionmentioning

confidence: 96%

Visualization of events inside kerfs during laser cutting of fusible metal

Yudin

Ковалев

2009

Journal of Laser Applications

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“…Annular nozzles were also proposed to control the purity of the assist gas. As noted by Powell et al [100], a 1% reduction in the purity of oxygen can produce a 25% reduction in cutting speed due to the reduction in energy supplied to the cutting front. Annular nozzles were used by Thomassen and Olsen [101] during laser cutting of steel.…”

Section: Proposals To Avoid Unsuitable Aerodynamic Interactionsmentioning

confidence: 99%

Laser Cutting: A Review on the Influence of Assist Gas

et al. 2019

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Assist gas plays a central role in laser fusion cutting. In this work, the aerodynamic interactions between the assist gas and the workpiece are reviewed. An insight into those phenomena that hinder the cutting quality and performance is provided. These phenomena include shock waves, choking, boundary layer separation, etc. The most relevant and promising attempts to overcome these common problems related to the gas dynamics are surveyed. The review of the current scientific literature has revealed some gaps in the current knowledge of the role of the assist gas dynamics in laser cutting. The assist gas interactions have been investigated only under static conditions; and the dynamic interaction with the molten material on the cutting front has not been addressed. New nozzle designs with improved efficiency of molten material removal are required to improve cut quality; and cutting speed in current industrial laser cutting machines; especially in those assisted by new high-brightness laser sources.

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“…where A b is absorptivity and r f is reflectivity. The energy produced by the exothermic reaction is generally of the same order of magnitude as the absorbed laser beam power (Powell et al, 1992). Assuming a pure oxygen supply for the assist gas, the following reaction occurs within the cutting kerf: Fe + 0.5O 2 = FeO and AH = -257.58 kJ/mol, where AH is the energy released during the reaction and the ignition point is about 1470 K (Geiger et al, 1988).…”

Section: Appendixmentioning

confidence: 99%

Improving Laser Cutting Quality for Two-Dimensional Contoured Paths

Pietro

Yao

1998

Journal of Manufacturing Science and Engineering

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Quality improvements in laser cutting of mild steel have been achieved by a newly developed model-based optimization strategy and its application to one-dimensional cut has been reported early. The specific aims of this paper are to assure quality of cut when cornering and generating small diameter holes. Such routines encompass a large proportion of all features processed on laser cutting systems, and therefore their successful production is significant. Currently, extensive trial-and-error based experimentation is needed in order to improve quality for these routines. Thus model-based optimization has the benefit of reducing this time-exhaustive step whilst leading to an optimal solution. Nonlinear power adaptation profiles are generated via the optimization strategy in order to stabilize cutting front temperatures. Uniform temperatures produce better quality by reducing (i) kerf widening effects, (ii) heat-affected zone extents, and (iii) workpiece self-burning effects. Experimental results are presented, and it is demonstrated that such process manipulation can produce significant quality improvements. In addition, predicted heat-affected zones correlate closely to those actually obtained. The process manipulation is successfully implemented in an industrial laser cutting system under laboratory condition.

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The role of oxygen purity in laser cutting of mild steel

Cited by 21 publications

References 1 publication

Visualization of events inside kerfs during laser cutting of fusible metal

Visualization of events inside kerfs during laser cutting of fusible metal

Laser Cutting: A Review on the Influence of Assist Gas

Improving Laser Cutting Quality for Two-Dimensional Contoured Paths

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