Melt ejection during laser drilling

2004 ◽  
Author(s):  
D. F. de Lange ◽  
A. Schoonderbeek ◽  
J. Meijer
Keyword(s):  
Laser Drilling ◽  
Melt Ejection

Modeling and Characterization of Laser Drilling of Small Holes on Metal Sheets

2004 ◽  
Author(s):  
Wei Han ◽  
Ryszard J. Pryputniewicz
Keyword(s):  
Laser Beam ◽  
Manufacturing Industry ◽  
Pulse Length ◽  
Experimental Studies ◽  
Laser Drilling ◽  
Melting Front ◽  
Laser Parameters ◽  
Metal Sheets ◽  
Small Holes ◽  
Melt Ejection

Laser drilling is increasingly being used in fabrication of small components in various materials with applications in aerospace, automotive, electronics and medical industries, and it offers a unique combination of benefits for the contemporary manufacturing industry as a rapid, precise, clean, flexible, and efficient process. Laser drilling involves a stationary laser beam which uses its high power density to melt or vaporize material from the workpiece, and the process is governed by an energy balance between the irradiating energy from the laser beam, the conduction heat into the workpiece, the energy losses to the environment, and the energy required for phase change in the workpiece. There are three major mechanisms of removal of material from the beam interaction zone and consequent propagation of the melt front into the metal bulk. They are (1) melt ejection due to interaction between the melt and an assisting gas, (2) melt ejection by the vaporization-induced recoil force, and (3) melt evaporation. The results of laser drilling processes, such as the profile of the heat affected zone (HAZ) and the geometry of the holes, strongly depend on settings of the laser parameters such as peak power, pulse length, pulse repetition rate, number of pulses, focal condition, etc. In addition, the processing results are strongly influenced by geometrical and material properties of the workpiece. This paper presents theoretical and experimental studies of laser drilling of micrometer size holes on metal sheets using a pulsed Nd:YAG laser. A model of the temperature distribution and the motion of the melting front for laser drilling is presented and compared with experimental data. Effects of laser parameters on the resultant geometry of the hole are investigated and summarized, and an optimum procedure for laser drilling of small holes on metal sheets is outlined.

Hydrodynamic Physical Modeling of Laser Drilling

2002 ◽  
Vol 124 (4) ◽  
pp. 852-862 ◽  
Author(s):  
D. K. Y. Low ◽  
L. Li ◽  
P. J. Byrd
Keyword(s):  
Material Removal ◽  
Laser Intensity ◽  
Low Carbon Steel ◽  
Laser Drilling ◽  
Low Carbon ◽  
Additional Energy ◽  
Complex Process ◽  
Threshold Time ◽  
Drilling Conditions ◽  
Melt Ejection

Laser drilling is a complex process that involves material removal through both vaporization and hydrodynamic melt ejection. The process is further complicated when an assist gas is incorporated, which is often the case under most practical drilling conditions. It is the intent of this article to investigate these effects through both experiments and theoretical analysis. The analysis accounts for conduction in the solid, vaporization, vaporization-induced recoil pressure melt ejection, convection due to the melt flow as well as the effects of using an O2 assist gas, which includes the effective assist gas pressure exerted on the melt surface, the forced convection cooling and the additional energy generated due to the oxidation of the melt surface by O2. The effects of the absorbed laser intensity on the melt surface temperature, melt ejection velocity and drilling velocity were studied for both cases of laser drilling with and without O2 assist gas and compared to experimental results obtained for EN3 low carbon steel. The dependence of threshold time on the absorbed laser intensity for either vaporization-dominated or melt ejection-dominated (hydrodynamic-dominated) material removal was studied and subsequently related to the threshold conditions for spatter formation. The model was subsequently optimized by examining the significance of the O2 effects considered.

Analysis of melt ejection during long pulsed laser drilling

2016 ◽  
Vol 25 (5) ◽  
pp. 054206 ◽  
Author(s):  
Ting-Zhong Zhang ◽  
Zhi-Chao Jia ◽  
Hai-Chao Cui ◽  
De-Hua Zhu ◽  
Xiao-Wu Ni ◽  
...  
Keyword(s):  
Pulsed Laser ◽  
Laser Drilling ◽  
Melt Ejection

Melt ejection during laser drilling of metals

2003 ◽  
Vol 356 (1-2) ◽  
pp. 414-424 ◽  
Author(s):  
K.T. Voisey ◽  
S.S. Kudesia ◽  
W.S.O. Rodden ◽  
D.P. Hand ◽  
J.D.C. Jones ◽  
...  
Keyword(s):  
Laser Drilling ◽  
Melt Ejection

Modeling and investigation of melt ejection dynamics for laser drilling with short pulses

2003 ◽  
Author(s):  
Andreas Ruf ◽  
Detlef Breitling ◽  
Peter Berger ◽  
Friedrich Dausinger ◽  
Helmut Huegel
Keyword(s):  
Laser Drilling ◽  
Short Pulses ◽  
Melt Ejection

Quantification of Melt Ejection Phenomena During Laser Drilling

2000 ◽  
Vol 617 ◽  
Author(s):  
K.T. Voisey ◽  
C.F. Cheng ◽  
T.W. Clyne
Keyword(s):  
Mild Steel ◽  
Flow Model ◽  
Collection Efficiency ◽  
Laser Drilling ◽  
Molten Material ◽  
Metallic Substrates ◽  
Heat Flow Model ◽  
Insight Into ◽  
Titanium Aluminium ◽  
Melt Ejection

AbstractDuring laser drilling, material removal in general occurs both by vaporisation and by the expulsion of molten material. The latter commonly arises as a result of the rapid build-up of gas pressure within the growing cavity as evaporation takes place, but the precise mechanisms responsible for the phenomenon are still unclear. The current work is aimed at gaining an insight into these mechanisms via measurements of the amount of material ejected from cavities during laser drilling under different conditions. Attention is first devoted to the issues which need to be considered when making experimental measurements of the fraction of material removed by melt ejection. These include the collection efficiency and the possibility of chemical changes occurring during the process. Results are then presented from work with a range of metallic substrates (mild steel, tungsten, copper, titanium, aluminium and nickel), drilled with a JK701 Nd-YAG laser under different conditions. Observed variations in the melt ejection levels have been studied for mild steel and aluminium and these are briefly considered in terms of the expected effects of certain material property values and the mechanisms of melt ejection. Results from an existing finite difference heat flow model are used to investigate the significance of melt ejection.

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