A method for identification and quantification of thermal lensing in powder bed fusion

Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedings – Annual report year: 2019Researchpeer-review

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With the increase in use of L-PBF for functional components, an increase in productivity demands higher laser power and continuous operation. However, both these factors can affect the optics involved. The principal components of a Laser Powder Bed Fusion system are the galvanometer mirrors and the focusing lens.
In the present work a method for identification and quantification of thermal lensing is proposed. Laser powder bed fusion experiments of stainless steel 316L powder was carried out at varying scan speeds and scan strategies in order to study the effects, of long exposure times, on the quality of single layer scans.
It was observed that the heating of silver-coated mirrors under continuous exposure led to a significant decrease in the beam quality as evidenced by weld track widening and loss in depth of melt pool penetration. Power measurements conducted at various locations along the beam path indicated that the mirrors were absorbing up to 42 % of the total power coming from the laser while also defocusing the beam.
Thus demonstrating the importance of including identification and quantification of thermal influence and possible instability of the optical elements as cause for irregular weld tracks.
Original languageEnglish
Title of host publicationProceedings of the 19th International Conference and Exhibition (EUSPEN 2019)
EditorsC. Nisbet, R. K. Leach, D. Billington, D. Phillips
PublisherThe European Society for Precision Engineering and Nanotechnology
Publication date2019
Pages230-233
ISBN (Electronic)978-099577514-5
Publication statusPublished - 2019
Event19th International Conference of the european Society for Precision Engineering and Nanotechnology (euspen 19) - Bilbao, Spain
Duration: 3 Jun 20197 Jun 2019

Conference

Conference19th International Conference of the european Society for Precision Engineering and Nanotechnology (euspen 19)
CountrySpain
CityBilbao
Period03/06/201907/06/2019

ID: 193294575