Hole taper control in laser percussion drilling using statistical modelling

2001 ◽  
Author(s):  
M. Ghoreishi ◽  
D. K. Y. Low ◽  
L. Li
Keyword(s):  
Statistical Modelling ◽  
Laser Percussion Drilling ◽  
Percussion Drilling

Statistical modelling of laser percussion drilling for hole taper and circularity control

2002 ◽  
Vol 216 (3) ◽  
pp. 307-319 ◽  
Author(s):  
M Ghoreishi ◽  
D K Y Low ◽  
L Li
Keyword(s):  
Pulse Width ◽  
Peak Power ◽  
Statistical Modelling ◽  
Pulse Frequency ◽  
Hole Diameter ◽  
Complete Analysis ◽  
Yttrium Aluminium Garnet ◽  
Controllable Factors ◽  
Laser Percussion Drilling ◽  
Percussion Drilling

The aim of the present work is to investigate the effects of different variables and their interactions in laser percussion drilling and to understand the possibility of controlling simultaneously the two important characteristics of a laser drilled hole: taper and circularity. Six variables, namely the peak power, pulse width, pulse frequency, number of pulses, assist gas pressure and focal plane position, were selected as independent controllable factors. The response surface method was used to statistically analyse the process. For each variable, five levels were considered and the experiments were performed based on a central composite design. A fibre-optic delivered neodymium-doped yttrium aluminium garnet laser was used to laser percussion drill mild steel sheets with a thickness of 2.5mm. The entrance diameter, the taper and the ratio of maximum to minimum Feret diameter for the hole entrance (circularity) were considered as responses/outputs in order to evaluate the process performance in terms of hole taper and circularity. Statistical modelling was carried out to develop mathematical models to relate the responses (outputs) to the six independent variables through multiple regression. A complete analysis of variance (ANOVA) was performed to test the significance of the obtained coefficients at 1, 5 and 7 per cent levels of significance. The developed models were verified by experiments. The work has shown that the pulse width and peak power have significant effects on the hole diameter, hole taper and hole circularity. However, the pulse frequency has no effect on these three hole characteristics. The number of pulses has no significant effect on hole diameter and circularity but has a significant effect on hole taper.

Influence of process gas sort and pressure on laser percussion drilling

2008 ◽  
Author(s):  
K. Walther ◽  
C. Holtkoetter ◽  
I. Kelbassa ◽  
R. Poprawe
Keyword(s):  
Process Gas ◽  
Laser Percussion Drilling ◽  
Percussion Drilling

scholarly journals Analytical model for the depth progress of percussion drilling with ultrashort laser pulses

2021 ◽  
Vol 127 (5) ◽  
Author(s):  
Daniel Holder ◽  
Rudolf Weber ◽  
Thomas Graf ◽  
Volkher Onuseit ◽  
David Brinkmeier ◽  
...  
Keyword(s):  
Analytical Model ◽  
Experimental Validation ◽  
Laser Pulses ◽  
Ultrashort Laser Pulses ◽  
Picosecond Pulses ◽  
Hole Depth ◽  
Laser Percussion Drilling ◽  
Pulse Energies ◽  
Ultrashort Laser ◽  
Percussion Drilling

AbstractA simplified analytical model is presented that predicts the depth progress during and the final hole depth obtained by laser percussion drilling in metals with ultrashort laser pulses. The model is based on the assumption that drilled microholes exhibit a conical shape and that the absorbed fluence linearly increases with the depth of the hole. The depth progress is calculated recursively based on the depth changes induced by the successive pulses. The experimental validation confirms the model and its assumptions for percussion drilling in stainless steel with picosecond pulses and different pulse energies.

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