Product Code: ICAL09_1501

Fiber Laser Welding of Titanium Alloys and Its Monitoring Through the Optical Combiner
Authors:
Barbara Previtali, Politecnico Di Milano; Milano Italy
Daniele Colombo, Politecnico di Milano; Italy
Presented at ICALEO 2009

A new monitoring configuration for fiber lasers (FLs) welding processes is proposed in which optical emissions from the welding pool are directly observed through the optical combiner of the FL source with spectroscopic equipment and fast photodiodes. This solution, referred as T.O.C. (Through the Optical Combiner) monitoring, can be easily installed on all FL sources in which an optical combiner is present. As a case study, T.O.C. monitoring in 1 kW cw FL welding of Titanium components for aerospace applications is presented.
Because of the optical configuration, no U.V. radiation from the plume is observed and monitoring can be performed only above 400 nm. Despite that, comparison with traditional monitoring configuration stated that results are almost comparable. Furthermore the tests confirmed that the high brilliances obtained with fiber laser sources allow electronic transitions when Ti alloys are laser welded. According to spectroscopic analysis on different welding conditions, different ranges in the Visible and N.I.R. domains were selected, isolated and analyzed making use of faster photodiodes equipment. Description of the T.O.C. device will be given ranging from the optical design to the software for data analysis; furthermore results from its application in Ti welding will be discussed proving the ability of the T.O.C. device to resolve common welding defects.