Application of high speed filming techniques to the study of rearwards melt ejection in laser drilling

Jones, Connor; Hann, David B.; Voisey, K.T.; Aitken, Scott

Abstract

Melt ejection is the dominant material removal mechanism in long, ms, pulse laser drilling of metals, a process with applications such as the drilling of cooling holes in turbine blades. Droplets of molten material are ejected through the entrance hole and, after breakthrough, through the exit hole. High speed filming is used to study the ejected material in order to better understand how this debris may interact with material in the immediate vicinity of the drilled hole. Existing studies have quantified various aspects of melt ejection, however they usually focus on ejection through the entrance hole. This work concentrates on rear melt ejection and is relevant to issues such as rear wall impingement. A 2kW IPG 200S fibre laser is used to drill mild steel. High speed filming is combined with image analysis to characterise the rearward-ejected material. Particle size and velocity data is presented as a function of drilling parameters. It is concluded that high speed filming combined with image analysis and proper consideration of process limitations and optimisation strategies can be a powerful tool in understanding resultant debris distributions.

Citation

Jones, C., Hann, D. B., Voisey, K., & Aitken, S. (in press). Application of high speed filming techniques to the study of rearwards melt ejection in laser drilling. Journal of Laser Applications, 29(2), Article 022204. https://doi.org/10.2351/1.4983269

• Journal Article Type: Article
• Conference Name: International Congress on Applications of Lasers & Electro-Optics (ICALEO)
• End Date: Oct 20, 2016
• Acceptance Date: Mar 28, 2017
• Online Publication Date: May 17, 2017
• Deposit Date: Aug 24, 2016
• Publicly Available Date: May 17, 2017
• Journal: Journal of Laser Applications
• Print ISSN: 1042-346X
• Electronic ISSN: 1938-1387
• Publisher: Laser Institute of America
• Peer Reviewed: Peer Reviewed
• Volume: 29
• Issue: 2
• Article Number: 022204
• DOI: https://doi.org/10.2351/1.4983269
• Keywords: laser drilling, melt ejection, high speed filming, high speed imaging, particle tracking, velocity measurement, image analysis
• Public URL: https://nottingham-repository.worktribe.com/output/861096
• Publisher URL: http://lia.scitation.org/doi/abs/10.2351/1.4983269
• Additional Information: Paper given at International Congress on Applications of Lasers & Electro-Optics (ICALEO), San Diego, USA, 16-20 October 2016
• Contract Date: Aug 24, 2016