Surface structuring of metals with short and ultrashort laser pulses

Weikert, Michael; Foehl, Christian; Dausinger, Friedrich; Abeln, Tobias

doi:10.1117/12.541081

Cited by 14 publications

(4 citation statements)

References 3 publications

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“…Within suitable process windows a gentle removal occurs without significant heat affected zones or a recast formation. This gentle processing represents the main advantage compared with the laser machining, in which micro-cracks, distortion and stress can result when using short laser pulses [8].…”

Section: Introductionmentioning

confidence: 99%

Thermal Analysis of Laser Chemical Machining: Part I: Static Irradiation

Messaoudi¹,

Eckert²,

Vollertsen³

2017

MSA

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The laser chemical machining is a non-conventional substractive processing method. It is based on the laser-activation of a material dissolution of metals in electrolyte ambient via local-induced temperature gradients and allows a gentle and smooth processing of especially temperature-sensitive metals. However, the material removal is characterized by a narrow process window and is restricted by occurring disturbances, which are supposed to be related to the localized electrolyte boiling. In order to control the removal quality and avoid disturbances, the correlation between the laser-induced temperatures and the resulting removal geometry has to be better understood. In this work an analytical modeling of the laser-induced temperatures at the surface of titanium based on a Green-function approach is presented. The main influencing factors (laser, electrolyte, material) as well as possible heat transfer into the electrolyte are included and discussed. To verify the calculated temperatures, single spot experiments are performed and characterized for titanium in phosphoric acid solution within laser irradiation of 1 s. The correlation between the temperature distribution and the resulting removal geometry is investigated based on a spatial superposition. Thereby, the bottom limit temperature is found to range between 63˚C and 70˚C whereas the upper limit is related to the nucleate boiling regime. Based on the performed correlation an indicator is identified to predict the ruling removal regime and thereby to reduce the experimental expenditure.

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Section: Introductionmentioning

confidence: 99%

Thermal Analysis of Laser Chemical Machining: Part I: Static Irradiation

Messaoudi¹,

Eckert²,

Vollertsen³

2017

MSA

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“…Laser machining, based on material ablation, is characterized by an increased machining precision and quality with shorter laser pulses. However, as the removal rate and the processing quality are reciprocal, the economic use of ultrashort pulsed lasers is still inefficient due to the high procurement costs and the low removal rates (typically 10 À3 mm 3 /min) [8]. Besides that, ECM is characterized by its smooth and low-cost machining.…”

Section: Introductionmentioning

confidence: 99%

Removal behavior and output quality for laser chemical machining of tool steels

et al. 2019

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Laser chemical machining represents a promising technology for manufacturing metallic micro parts. It is usually based on the selective thermal activation of electrochemical material dissolution of self-passivating metals in an electrolyte environment. Prior to widespread industrial acceptance, its machining quality needs to be classified within the subtractive machining processes and the range of machinable materials needs to be expanded. For this purpose, line and square cavities with dimensions ≤300 μm are machined into high speed steel HS10-4-3-10 in a H3PO4-environment and compared to those of the self-passivating cobalt-chrome alloy Stellite 21. As a result, the laser-induced removal velocities in HS10-4-3-10 amount to 50 μm/s. These are two orders of magnitudes higher than the background etching (2 nm/s at room temperature) and three times higher than those obtained in Stellite 21 (12 μm/s). However, the microscopic and spectroscopic analyses of both materials reveal a high shape accuracy with edge radii from 10 to 20 μm, a surface roughness down to 0.8 μm and a negligible microstructural impact. Despite lower removal rates and higher surface roughness, laser chemical machining provides higher dimensional accuracy in comparison with micro milling and shows its suitability for micro machining of structures <200 μm.

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“…Laser machining, based on material ablation, is characterized by an increased machining precision and quality with shorter laser pulses. However, as the removal rate and the processing quality are reciprocal, the economic use of ultrashort pulsed lasers is still inefficient due time-and the high procurement costs and the low removal rates (typically 10 -3 mm 3 /min) [8]. Besides, ECM is characterized by its smooth and lowcost machining.…”

Section: Introductionmentioning

confidence: 99%

Chances and Limitations in the Application of Laser Chemical Machining for the Manufacture of Micro Forming Dies

et al. 2018

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Laser chemical machining, a non-conventional processing method based on thermally activated electrochemical material dissolution, represents a promising technology for manufacturing metallic dies for micro forming applications. Prior to widespread industrial acceptance the machining quality of laser chemical machining should be characterized. For this purpose, laser chemical machining is compared with micro milling regarding both the dimensional accuracy and the surface quality. Therefore, square micro cavities exhibiting side walls between 100 μm and 400 μm in length and 60 μm in depth are machined with both manufacturing processes into the cobalt-chrome alloy Stellite 21. The geometrical features are investigated using laser-scanning confocal microscopy and scanning electron microscopy. On the one hand, laser chemical machining is more suitable for manufacturing cavities with dimensions < 200 μm due to higher shape accuracy with stable mean edge radii of (11.2 ± 1.3) μm as a result of roughing and finishing steps. On the other hand, the finish quality of micro milling with mean surface roughness Sa of 0.2 μm could not be achieved with laser chemical machining due to in-process induced waviness. Finally, the metallographic analysis of the surface-near layers reveals that both manufacturing processes ensure gentle machining without any noticeable micro structural impact.

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Surface structuring of metals with short and ultrashort laser pulses

Cited by 14 publications

References 3 publications

Thermal Analysis of Laser Chemical Machining: Part I: Static Irradiation

Thermal Analysis of Laser Chemical Machining: Part I: Static Irradiation

Removal behavior and output quality for laser chemical machining of tool steels

Chances and Limitations in the Application of Laser Chemical Machining for the Manufacture of Micro Forming Dies

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