Fusing optical coherence tomography and photodiodes for diagnosis of weld features during remote laser welding of copper-to-aluminum

Brežan, Tine (author), Franciosa, Pasquale (author), Jezeršek, Matija (author), Ceglarek, Dariusz (author)

This study has been designed to investigate whether variations in the features of laser weldments can be isolated and diagnosed by fusing photodiodes and optical coherence tomography (OCT). Two manufacturing scenarios (variation in laser power and focal offset) have been considered during remote laser welding of 0.2 mm thick Cu foils on 2 mm thick Al 1050 plates with an adjustable ring mode laser integrated with a 1D oscillation head. The process was monitored by measuring weld penetration depth with OCT and by process emissions (plasma and back-reflection) via photodiodes. The acquisition frequency of all signals was 40 kHz. Strong correlations (r > 0.75) were shown between plasma, back-reflection, and OCT signals and measured depth and width of the weld. Weak correlations (r < 0.5) between voids, cracks, and sensor signals were observed. Although plasma is the predominant signal that carries most of the information about the process, and the OCT allows direct measurement of the penetration depth, their integration reached 87% classification accuracy of the tested welding scenarios. The main misclassification was observed between “good weld” and “over weld,” defined by the measured weld depth. Sensor fusion strategies with manufacturing implications are discussed throughout the paper.

• Language: English
• Keywords: laser welding, process monitoring, OCT, photodetectors
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 10 str,
• Numbering: Vol. 35
• PID: 20.500.12556/RUL-143900
• UDC: 621.791
• ISSN on article: 1042-346X
• DOI: 10.2351/7.0000803
• COBISS.SI-ID: 138309123
• Publication date in RUL: 18.01.2023

Record is a part of a journal

• Title: Journal of laser applications
• Shortened title: J. laser appl.
• Publisher: Laser Institute of America
• ISSN: 1042-346X
• COBISS.SI-ID: 14231813

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: lasersko varjenje, nadzor procesa, OCT, fotodetektorji

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0392
• Name: Optodinamika