Geometrical aspects of laser-drilled high precision holes for flow control applications

Giedl, R.; Helml, H.-J.; Wagner, F.; Wild, Michael J.

doi:10.1117/12.540609

Cited by 9 publications

(6 citation statements)

References 1 publication

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“…Laser drilling is a method to drill especially holes in the micro-range with highly defined shape, zero-taper geometry [12], and high-aspect ratio [13,14]. Compared with mechanical drilling, laser drilling offers a broader variety of possible strategies.…”

Section: Introductionmentioning

confidence: 99%

“…With these processes, it is only possible to drill micro-holes, which are conical, whereby the taper angle is positive. The most advanced process technique offers drilling cylindrical holes or even holes with a positive taper angle [12]. The beam is controlled using special optics allowing to tilt the beam with an inclination of up to ± 5°forming holes with no or negative taper angle [17].…”

Section: Introductionmentioning

confidence: 99%

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Geometry assessment of ultra-short pulsed laser drilled micro-holes

Putzer

Ackerl

Wegener

2020

Int J Adv Manuf Technol

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Ultra-short pulsed laser ablation enables a defined generation of micro-holes. A parameter study on the ablation characteristics of copper clearly reveals a benefit for green wavelength with lower threshold fluence, simultaneously increasing the Rayleigh length. The use of a circular drilling method allows a defined manufacturing of micro boreholes and micro through-holes with 35 μm diameter of up to 165 μm and 300 μm length. Introducing high-resolution micro-computed X-ray tomography studying the micro-hole evolution and adjacent geometrical transformations reveals micrometer resolution and high usability. The conical geometry evolving up to an aspect ratio of 5:1 fits well to established models known for percussion drilling. However, increasing the number of pulses leads to non-conical geometry evolution, and this resulting geometry is studied for the first time. Henceforth, the exact geometrical evolution from conical to cylindrical shape upon laser drilling can be resolved revealing the impact of multiple reflections at the generated steep flanks.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geometry assessment of ultra-short pulsed laser drilled micro-holes

Putzer

Ackerl

Wegener

2020

Int J Adv Manuf Technol

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“…It is state of the art that a suitable choice of process parameters [1][2][3][4] and choice of the irradiation angle of the laser beam with respect to the inclined sample surface [5] highly influences the kerf taper. Helical laser drilling allows machining of holes with 0° or even a negative kerf taper with an inclined laser beam [6][7][8][9][10]. Due to the dynamic ability to precisely position the laser beam in 5 axes with the new micromachining subsystem precSYS from SCANLAB, it can be effectively combined with an USP (ultra-short pulsed)…”

Section: Introduction mentioning

confidence: 99%

Taper Angle Correction in Cutting of Complex Micro-mechanical Contours with Ultra-Short Pulse Laser

Auerswald¹,

Ruckli²,

Weber³

et al. 2016

JMEA

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The objective of this work was to investigate the possibility of taper angle correction in cutting of complex micro-mechanical contours using a TruMicro ultra-short pulse laser in combination with the SCANLAB precSYS micro machining sub system. In a first step, the influence of the process parameters on the kerf taper angle of metallic alloys was systematically investigated without beam inclination. A set of base parameters was derived for the subsequent investigations. In a second step, the kerf taper angle was controlled by static beam inclination. In a third step, the same optics was used in its dynamic precession mode to fabricate micro-mechanical components of complex contours with perpendicular 0° taper angles. It was found that taper angle adjustments of up to 7.5° are possible with the used setup for cutting applications. Taper angle control is possible both in the static beam inclination mode and in the dynamic precession mode. The static mode could be interesting for contours with sharp inner radii and for achieving faster cutting times similar to results with fixed optics, but would require excellent synchronization of beam inclination and axis motion. The dynamic precession mode would allow an easier integration of the optics into a laser machine but will result in longer cutting times and limitations with respect to achievable inner radii.

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“…Micro-holes, small holes with diameter less than 0.5 mm [1], have a wide range of applications, including ink-jet printer nozzles, orifices for bio-medical devices, cooling vents for gas turbine blade and diesel fuel injector spray holes. Microholes can be fabricated by electrical discharge machining (EDM) [2], laser drilling [3], electrochemical machining [4] or conventional drilling [5]. The micro-hole for a diesel engine fuel injector, as is illustrated in figure 1, is representative of a high volume production application.…”

Section: Introductionmentioning

confidence: 99%

“…Giedl et al [3] have classified the shape of a micro-hole: negative taper, positive taper and rounded flow entry, as is shown in figure 3. In EDM drilling, if the process parameters remain the same throughout the drilling, the hole will have positive taper due to the wear of a wire electrode.…”

Section: Introductionmentioning

confidence: 99%

Form measurements of micro-holes

Kao

Shih²

2007

Meas. Sci. Technol.

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The form measurement and gauge repeatability and reproducibility (R&R) of a micro-hole using a coordinate measurement machine (CMM) with a combination of optical and contact sensors were conducted in this study. The micro-holes, about 160 µm in diameter and 0.9 mm in depth, were fabricated using the electrical discharge machining process for diesel fuel injectors. The shape and size of micro-holes are important for the desired spray pattern, fuel economy and exhaust emission of diesel engines. In this study, the setup of the measurement machine and the procedure to determine the contact points are presented. Five form characteristics, the cylindricity, diameter, roundness, straightness and taper, of the micro-hole are analyzed from measurement points. The gauge R&R test is conducted to determine the micro-hole form measurement capability and to calculate the tolerance specifications for each characteristic that the CMM is capable of measuring. An example to quantify the change in the shape of the micro-holes before and after the abrasive flow machining is presented.

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Geometrical aspects of laser-drilled high precision holes for flow control applications

Cited by 9 publications

References 1 publication

Geometry assessment of ultra-short pulsed laser drilled micro-holes

Geometry assessment of ultra-short pulsed laser drilled micro-holes

Taper Angle Correction in Cutting of Complex Micro-mechanical Contours with Ultra-Short Pulse Laser

Form measurements of micro-holes

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