Vpliv procesnih parametrov na makroskopsko odvzemanje materiala z lasersko ablacijo z visokimi frekvencami bliskov

Hribar, Luka (author), Gregorčič, Peter (mentor), Jezeršek, Matija (comentor)

V disertaciji raziskujemo proces laserske ablacije pri makroskopskem odstranjevanju dveh industrijsko zanimivih materialov (jekla AISI 316L in medenine CuZn37) pri visokih frekvencah bliskanja (> 10 kHz). Preučili smo vpliv izbranih okoliških parametrov, parametrov laserskega sistema ter materialnih lastnosti na hitrost odstranjevanja materiala, energijsko učinkovitost procesa in kakovost lasersko obdelane površine z nanosekundnimi bliski valovne dolžne 1064 nm, ki jih seva vlakenski Yb laser. Rezultati kažejo, da hitrost odstranjevanja materiala (MRR) monotono narašča z dolžino bliskov, medtem ko se s frekvenco bliskanja linearno povečuje do karakteristične vrednosti (f0), kjer sta najvišji tako energija bliskov kot povprečna moč laserja. Največjo vrednost MRR smo dosegli pri frekvenci bliskanja, ki je višja ali kvečjemu enaka f0, natančna vrednost ekstrema pa je odvisna od korelacije med frekvenco in fluenco laserskih bliskov ter od materialnih lastnosti vzorca. Stopnja prekrivanja pomembno vpliva na hrapavost obdelovane površine (Sa), najboljše razmerje med hitrostjo ablacije in kakovostjo površine pa dosežemo pri približno 50-odstotnem prekrivanju laserskih bliskov, neodvisno od obdelovanega materiala. Ta spoznanja smo uspešno implementirali tudi na realnih industrijskih primerih (dinamično uravnoteženje polipropilenskih rotorjev v gibanju in površinske mikroobdelave magnetoaktivnih elastomerov). S tem smo demonstrirali, da je predstavljen pristop relativno univerzalen, saj smo ga lahko uporabili tako na kovinah (jeklo in medenina) kot na trdih (polipropilen s steklenimi vlakni) in mehkih (polidimetilsiloksan z železovimi vključki) kompozitnih materialih.

• Language: Slovenian
• Keywords: laserska ablacija, vlakenski laser, interakcija svetloba – snov, magnetoaktivni elastomeri, rotorji
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [L. Hribar]
• Year: 2023
• Number of pages: XXVI, 132 str.
• PID: 20.500.12556/RUL-152279
• UDC: 535.374:621.9.048.7(043.3)
• COBISS.SI-ID: 174191363
• Publication date in RUL: 16.11.2023

HRIBAR, Luka, 2023, Vpliv procesnih parametrov na makroskopsko odvzemanje materiala z lasersko ablacijo z visokimi frekvencami bliskov [online]. Doctoral dissertation. Ljubljana : L. Hribar] . [Accessed 16 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=152279

Secondary language

• Language: English
• Title: The influence of processing parameters on macroscopic removal of material by laser ablation at high repetition rates

Abstract

In this dissertation, we investigate the process of laser ablation during macroscopic removal of two industrially interesting materials (AISI 316L steel and CuZn37 brass) using high repetition rates (> 10 kHz). We studied the influence of selected environmental parameters, laser system parameters, and material properties on the material removal rate (MRR), energy efficiency of the process, and quality of the laser-treated surface using nanosecond pulses at a wavelength of 1064 nm emitted by a Yb fiber laser. The results show that the MRR increases monotonically with pulse duration, while it increases linearly with repetition rate up to the characteristic value (f0) at which both the pulse energy and the average laser power are highest. The maximum MRR is reached at a repetition rate higher than or at most equal to f0. The exact value of the extreme depends on the correlation between the repetition rate and the fluence of the laser pulses, as well as on the material properties of the sample. The degree of overlap has a significant effect on the surface roughness (Sa), and the best ratio between ablation rate and surface quality is achieved at about 50 % overlap of the laser pulses, regardless of the material being processed. We have successfully applied these findings to real industrial examples (dynamic balancing of polypropylene rotors in motion and surface micromachining of magnetoactive elastomers), demonstrating that the presented approach is relatively universal, as we were able to apply it to metals (steel and brass) as well as to hard (glass fiber reinforced polypropylene) and soft (polydimethylsiloxane with iron inclusions) composite materials.

• Keywords: laser ablation, fiber laser, laser-material interaction, magnetoactive elastomers, rotors