Hole Taper Characterisation and Control in Laser Percussion Drilling

Li, L.; Low, D. K. Y.; Ghoreshi, Majid; Crookall, J.R.

doi:10.1016/s0007-8506(07)61488-7

Cited by 61 publications

(42 citation statements)

References 7 publications

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“…Hole tapering in laser drilling has been reported many times, but it is almost always shaped like letter Y, i.e., the taper is not constant throughout. Instead, there is significant tapering close to the entry hole, after which the width of the hole stays mostly constant [32,37]. Drilling experiments in this study resulted in almost perfectly conical holes, due to the technique that was employed.…”

Section: Evaluation Of the Microstructuresmentioning

confidence: 69%

“…The decrease in hole diameter seen here is likely the beginning of a transition from a highly thermal process, where the primary mechanism of material removal is the ejection of molten material by vapor pressure, to material removal by direct evaporation. hole erosion due to the upwards melt flow, as discussed by Li et al [32]. In practice, the entry hole will always be slightly rounded in laser drilling, unless the material is directly vaporized by a high enough power density.…”

Section: Hole Diametersmentioning

confidence: 98%

“…Too large entry holes can usually be fixed by using a large enough beam offset with the control program. However, even with corrections, it is difficult to prevent entry hole erosion due to the upwards melt flow, as discussed by Li et al [32]. In practice, the entry hole will always be slightly rounded in laser drilling, unless the material is directly vaporized by a high enough power density.…”

Section: Hole Diametersmentioning

confidence: 99%

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Comparison of Laser-Engraved Hole Properties between Cold-Rolled and Laser Additive Manufactured Stainless Steel Sheets

et al. 2017

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Laser drilling and laser engraving are common manufacturing processes that are found in many applications. With the continuous progress of additive manufacturing (3D printing), these processes can now be applied to the materials used in 3D printing. However, there is a lack of knowledge about how these new materials behave when processed or machined. In this study, sheets of 316L stainless steel produced by both the traditional cold rolling method and by powder bed fusion (PBF) were laser drilled by a nanosecond pulsed fiber laser. Results were then analyzed to find out whether there are measurable differences in laser processing parts that are produced by either PBF (3D printing) or traditional steel parts. Hole diameters, the widths of burn effects, material removal rates, and hole tapers were measured and compared. Additionally, differences in microstructures of the samples were also analyzed and compared. Results show negligible differences in terms of material processing efficiency. The only significant differences were that the PBF sample had a wider burn effect, and had some defects in the microstructure that were more closely analyzed. The defects were found to be shallow recesses in the material. Some of the defects were deep within the material, at the end and start points of the laser lines, and some were close to the surfaces of the sample.

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Section: Evaluation Of the Microstructuresmentioning

confidence: 69%

Section: Hole Diametersmentioning

confidence: 98%

Section: Hole Diametersmentioning

confidence: 99%

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Comparison of Laser-Engraved Hole Properties between Cold-Rolled and Laser Additive Manufactured Stainless Steel Sheets

et al. 2017

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“…Even at a magnification of 350 the diameters are overestimated by 30% (Fig. 5) The square sieves were fabricated using percussion drilling [4] with five laser shots per hole, in aluminium foils with a thickness of 50µm (Fig. 3).…”

mentioning

confidence: 99%

Laser manufacturing of microsieves for bioengineering applications

Łapiński

Bogdanowicz

Marczak

et al. 2015

Photon. Lett. Poland

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Abstract-Laser drilling is a noncontact technology which allows high flexibility and full automation of the process. The present research aimed at developing laser technology for manufacturing microsieves in thin Ni and Al foils. Involute and square distributions of holes were formed with an overall dimension of 3mm. The distance between adjacent holes was 25µm to 100µm, which meant fabricating up to 10,000 openings per microsieve. Owing to the optimisation of optical system design and laser micromachining system parameters, holes with a desired diameter of around 12µm were fabricated, limited only by the diffraction divergence of a laser beam.

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“…Ghoreishi et al [7][8][9] studied the effects of the six independent factors and their effects on hole taper and hole circularity in laser percussion drilling. They carried out their experiments on mild steel and stainless steel materials.…”

mentioning

confidence: 99%

Statistical analysis of repeatability in laser percussion drilling

Ghoreishi¹

2005

Int J Adv Manuf Technol

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This study investigates the effect of six parameters in the repeatability of drilled holes in laser percussion drilling process by means of statistical techniques. Peak power, pulse width, pulse frequency, number of pulses, gas pressure and focal plane position were considered as independent process parameters. Experiments were designed with the aim of reducing the number of required experiments. The response surface method was used to develop the models for required responses. The significant factors in the process were selected based on the analysis of the variance (ANOVA). The experiments were conducted in mild steel sheet with a thickness of 2 mm. Each experiment was repeated 35 times in order to investigate the repeatability of the process. The equivalent entrance diameter, percentage of standard deviation of entrance diameter (%STD Eq Dia), circularity (ratio of minimum to maximum Feret's diameter) and its standard deviation (STD circularity) were selected as process characteristics. The %STD Eq Dia and STD circularity, respectively, show the repeatability of equivalent diameter and circularity in the process.The results show that the process of drilling smaller hole diameters is more repeatable than drilling larger holes. Pulse width, gas pressure, focal plane position, peak power and number of pulses, respectively, have significant effect on the repeatability of hole diameter and circularity. Pulse frequency has no significant effect on the repeatability of the process.

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Hole Taper Characterisation and Control in Laser Percussion Drilling

Cited by 61 publications

References 7 publications

Comparison of Laser-Engraved Hole Properties between Cold-Rolled and Laser Additive Manufactured Stainless Steel Sheets

Comparison of Laser-Engraved Hole Properties between Cold-Rolled and Laser Additive Manufactured Stainless Steel Sheets

Laser manufacturing of microsieves for bioengineering applications

Statistical analysis of repeatability in laser percussion drilling

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