The oxidation dynamics of laser cutting of mild steel and the generation of striations on the cut edge

Ivarson, Anders; Powell, John; Kamalu, John; Magnusson, Claes

doi:10.1016/0924-0136(94)90461-8

Cited by 81 publications

(50 citation statements)

References 2 publications

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“…Classical heat and mass transfer laws are fully appropriate when applied to modeling those machining processes [1], and it is generally the view that thermal problems in this time regime have been well understood and solved. In the majority of industrial practice, however, [7] laser cutting of steel (sometimes including stainless steel) uses oxygen as an assisting gas to provide exothermic energy, and to help increase cutting speed. One important phenomenon in oxygen-assisted cutting is the formation of striation [5].…”

Section: Continuous Wave Laser Cuttingmentioning

confidence: 99%

“…One important phenomenon in oxygen-assisted cutting is the formation of striation [5]. The explanations given for this phenomenon have been internal instability of the cutting process [6], and cyclic oxidation [7], which is shown as Fig. 2.…”

Section: Continuous Wave Laser Cuttingmentioning

confidence: 99%

“…Once the oxide is blown out from the cutting front, due to a sudden decrease of the oxide layer, another expansion will begin. Although [7] gives a quite convincing explanation on the expansion of the oxide layer, it does not clearly explain how the oxide layer is suddenly reduced. Moreover, the explanation is empirically based, and when quantitative analysis is needed, the heat transfer and energy balance will become more complex in modeling the cutting process when the oxygen diffusion and oxidation process are taken into account.…”

Section: Continuous Wave Laser Cuttingmentioning

confidence: 99%

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Time scale effects in laser material removal: a review

Yao

Chen

Zhang

2004

Int J Adv Manuf Technol

100

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In laser material removal using a continuous wave or long-pulsed laser, the primary material removal mechanism melts with molten metal often ejected by an assisting oxygen jet. Interactions between heat transfer, oxygen diffusion, and gas dynamics have been studied. In laser machining using a Q-switched solid state laser with pulse width on the order of nanoseconds, the primary material removal mechanism is ablation, but substantial melting is still present if a metallic material is concerned. Two mechanisms, ablation and melting, are modeled together and the property discontinuity and boundary conditions at the liquid/vapor interface are provided. When the laser pulse width further reduces to the order of picoseconds or femtoseconds, as in a Ti:sapphire laser, the dominant material removal mechanism changes yet again, with little thermal damage and wavelength independence observed. Thermal aspects are examined in the context of the short timescales of these pulses compared with the timescale of photon-electron-lattice interactions. Research needs in laser material removal in each of the three time regimes are discussed.

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Section: Continuous Wave Laser Cuttingmentioning

confidence: 99%

Section: Continuous Wave Laser Cuttingmentioning

confidence: 99%

Section: Continuous Wave Laser Cuttingmentioning

confidence: 99%

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Time scale effects in laser material removal: a review

Yao

Chen

Zhang

2004

Int J Adv Manuf Technol

100

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“…Roughness was very high when pulse laser was used at high speeds due to the lack of overlap between pulses. Oxygen and air also caused more roughness than nitrogen, which can be explained by the formation of striation lines due to the exothermic reactions [16]. 8.…”

Section: Resultsmentioning

confidence: 99%

Using a Nd:YAG laser and six axes robot to cut zinc-coated steel

Ghany

Rafea

Newishy

2005

Int J Adv Manuf Technol

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Zinc-coated steel sheets are important materials in the automobile and home appliance industries. Currently, lasers are the preferred tools for metal cutting because of their good cutting quality, flexibility and excellent features and results, as compared to traditional tools. The solid-state Nd:YAG laser has successfully replaced the gaseous CO 2 laser for metal cutting; its small size and short wavelength makes it suitable for cutting bright and metal-coated materials, as well as being able to be transmitted via optical fibers and robots to cut complicated three dimensional and curved shapes. In this work, the Nd:YAG laser is used to cut 1 mm zinc coated steel sheets. We demonstrate the effects of different cutting parameters such as laser power, cutting speed, different gas types and pressures, and focus position on the cutting quality characteristics of attached dross, kerf width and cut surface roughness. Using a six axes robot, cutting speed was limited to 6 m/min because of the noticeable vibration at higher speeds. Results showed that the cutting surfaces achieved were very sharp and smooth. In cutting, Nd:YAG required less power and attained higher speeds than the published results of a CO 2 laser, which makes Nd:YAG an economical alternative to cut zinc and metal-coated materials. In addition, laser cutting using robots provided efficient and consistent cutting quality, especially in the case of 3D and countered cutting. Apart from using low speed, robots proved to be more economical than costly, specially designed CNC tables.

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“…The partially oxidised melt produced has a lower viscosity than the unoxidised melt produced when nitrogen is employed [16]. This lower viscosity melt can be more easily ejected.…”

Section: Piercing With Oxygenmentioning

confidence: 92%

Fibre laser piercing of mild steel – The effects of power intensity, gas type and pressure

Hashemzadeh

Powell

Voisey

2014

Optics and Lasers in Engineering

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Laser piercing is used to generate a starting point for laser cutting. The pierced hole is normally larger than the kerf width, which means that it cannot lie on the cut line. An experimental program investigating the piercing process as a function of laser and assist gas parameters is presented. An Nd:YAG fibre laser with a maximum power of 2 kW was used in continuous wave mode to pierce holes in 2 mm thick mild steel. Oxygen and nitrogen were used as assist gases, with pressures ranging from 0.3 to 12 bar. The sizes, geometries and piercing time of the holes produced have been analysed. The pierced hole size decreases with increasing gas pressure and increasing laser power. Oxygen assist gas produced larger diameter holes than nitrogen. A new technique is presented which produces pierced holes no larger than the kerf with and would allow the pierced hole to lie on the cut line of the finished product -allowing better material usage. This uses an inclined jet of nitrogen when piercing prior to oxygen assisted cutting.

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The oxidation dynamics of laser cutting of mild steel and the generation of striations on the cut edge

Cited by 81 publications

References 2 publications

Time scale effects in laser material removal: a review

Time scale effects in laser material removal: a review

Using a Nd:YAG laser and six axes robot to cut zinc-coated steel

Fibre laser piercing of mild steel – The effects of power intensity, gas type and pressure

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