CC BY
13HiLASE-I-12
High speed laser surface texturing and time-resolved temperature measurement
J. Martan1, D. Moskal1, M. Kucera1, L. Prokesova1, M. Honner1
1University of West Bohemia, New Technologies - Research Centre, Plzen, Czech Republic
Laser micromachining using high power ultrashort pulsed lasers is the scientific field of intensive developments in last years. Although the process is so called "cold ablation", for high power lasers, thermal effects occur and can cause degradation of material or surface topography. An innovative laser surface texturing (LST) method was developed to enable high processing speeds and low thermal effects at the same time. It is called shifted LST method [1]. In order to be able to characterize the heat accumulation in material in pulse laser processes, a measurement system was developed for time resolved temperature measurements in nanosecond time scale. It is based on high speed infrared detectors (Fig. 1). The system was first used to characterize laser marking of stainless steel by a nanosecond laser [2]. It was found that for shorter pulse duration the temperature rises over the melting temperature and causes melting and decrease of corrosion resistance. After that, the system was used to evaluate heat accumulation in laser surface texturing by different methods, including the shifted LST. For the used 14 W average power picosecond laser system, the heat accumulation was detected for very low scanning speeds (< 0.05 m/s) for all pulse energies in machining of lines and for certain scanning strategies in laser surface texturing
of dimples. The shifted LST method proved to be a reliable method for precision surface texturing at high scanning and processing speeds. The fast temperature measurement system can be used as a tool for technology developers for comparing different scanning strategies and material removal approaches and for choosing the right strategy for the desired application. This will be mainly important for kW class pulsed lasers.
Fig. 1.
The work has been supported by the Ministry of Education, Youth and Sports of the Czech Republic (OP RDI program, CENTEM project, no. CZ.1.05/2.1.00/03.0088, co-funded by the ERDF) and ERDF ("LABIR-PAV / Pre-application research of infrared technologies" project, No. CZ.02.1.01/0.0/0.0/18_069/0010018).
References
[1] J. Martan, D. Moskal, M. Kucera, Laser surface texturing with shifted method — Functional surfaces at high speed, J. Laser Appl. 022507 (2019) 1-9.
[2] M. Kucera, J. Martan, A. Franc, Time-resolved temperature measurement during laser marking of stainless steel, Int. J. Heat Mass Transf. 125 (2018) 1061-1068.
