Ablation characteristics of picosecond laser single point drilling of Si3N4 under dry and water medium

• Published in: Procedia CIRP Vol. 95; pp. 938 - 943
• Main Authors: Zahrani, Esmaeil Ghadiri, Azarhoushang, Bahman, Wilde, Jürgen, Zahedi, Ali
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2020
• Subjects: Ablation depth; Laser focus point; Picosecond Laser single point ablation; Si3N4; Under-water laser-machining; Si3N4; Under-water laser-machining; Picosecond Laser single point ablation; Ablation depth; Laser focus point
• ISSN: 2212-8271; 2212-8271
• DOI: 10.1016/j.procir.2020.04.144

Single point laser ablation of Si3N4 under dry and water medium is investigated and analysed. The experiments were conducted based on the one-factor-at-a-time strategy considering various input parameters such as piercing time, focus point position and water layer thickness. The effects of process inputs on the ablated hole’s geometrical features including the ablation depth and diameter, hole taper, and hole edge roundness under presence and absence of water as an intermediate medium are studied. The laser focus point position was determined and varied during the investigation. It was found that, compared to the dry condition, the maximum ablation depth under wet condition is much more sensitive to the position of the laser focus point. It was also observed that the ablation depth is directly influenced by the piercing time in both dry and under water conditions. Picosecond laser single point ablation under a water layer with a thickness of 0.6 mm could increase the ablation depth up to 23%, compared to the dry condition. However, the ablation depth was significantly decreased by increasing the water layer thickness. Additionally, the hole entrance edge was rounded with increasing the water layer thickness. The hole taper was significantly influenced by the water layer thickness.