Ultrafast laser applications in the kW‐class

Holder, Daniel; Henn, Manuel; Peter, Alexander; Faas, Sebastian; Feuer, Anne; Freitag, Christian; Weber, Rudolf; Onuseit, Volkher; Graf, Thomas

doi:10.1002/phvs.202200028

Cited by 4 publications

(2 citation statements)

References 26 publications

(27 reference statements)

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“…The tubes were then shifted by 200 mm in x -direction using the x 2 axis of the x–y- stage for texturing the adjacent area. This stitching approach allows to functionalize large and heavy samples, as previously shown for an injection mold steel tool with a length of 500 mm and with a weight of 500 kg 45 .…”

Section: Methodsmentioning

confidence: 89%

Enhancing heat transfer at low temperatures by laser functionalization of the inner surface of metal pipes

Holder,

Peter,

Kirsch

et al. 2024

Sci Rep

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The latent heat transfer during vapour condensation in the condenser section of passive heat transport devices such as the two-phase closed thermosiphon is limited by film condensation. Dropwise condensation provides an increase of the heat transfer coefficient by up to one order of magnitude and can be achieved with a water-repellant surface. The inner surface of pipes made from stainless steel was functionalized by laser surface texturing with ultrashort laser pulses and subsequent storage in a liquid containing long-chained hydrocarbons. The pipes were separated into half-pipes by wire eroding to enable laser texturing of the inner surface, and were then joined by electron beam welding after laser texturing. As a result, superhydrophobic and water-repellent surfaces with a contact angle of 153° were obtained on the inner surface of the pipes with a length of up to 1 m. The functionalized pipes were used in the condenser section of a two-phase closed thermosiphon to demonstrate a heat transfer rate of 0.92 kW at 45 °C, which is approximately three times the heat transfer rate of 0.31 kW of a smooth reference pipe.

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Section: Methodsmentioning

confidence: 89%

Enhancing heat transfer at low temperatures by laser functionalization of the inner surface of metal pipes

Holder,

Peter,

Kirsch

et al. 2024

Sci Rep

Self Cite

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“…Both topics will be addressed by the use of a novel high-power, thindisk multipass laser system developed at the IFSW. This system is capable of emitting a nearly diffraction-limited output beam composed of continuous wave or ultrashort pulsed radiation or both continuous wave and ultrashort pulsed radiation [13] with the potential for adapted processing strategies for high-power laser micromachining [14].…”

Section: Discussionmentioning

confidence: 99%

Bridging additive and subtractive manufacturing

Holder,

Henn,

Buser

et al. 2024

PhotonicsViews

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Additive manufacturing with laser powder‐bed fusion (PBF‐LB/M) can generate complex metal parts with a high degree of design freedom, which are already being used in various industries. However, the PBF‐LB/M process faces some limitations in achievable surface quality and feature size. To address these challenges, we have developed a novel hybrid manufacturing approach that combines additive manufacturing via PBF‐LB/M with subtractive manufacturing via ultrafast laser machining. By alternating between additive and subtractive processes, it is possible to not only mitigate the limitations of each process but also to introduce new functionality. This synergistic combination enables the creation of parts with superior surface finishes and deep and narrow internal features that are not possible with a single method alone.

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