Analytical Model for the Depth Progress during Laser Micromachining of V-Shaped Grooves

Abstract

An analytical model is presented that allows predicting the progress and the final depth obtained by laser micromachining of grooves in metals with ultrashort laser pulses. The model assumes that micromachined grooves feature a V-shaped geometry and that the fluence absorbed along the walls is distributed with a linear increase from the edge to the tip of the groove. The depth progress of the processed groove is recursively calculated based on the depth increments induced by successive scans of the laser beam along the groove. The experimental validation confirms the model and its assumptions for micromachining of grooves in a Ti-alloy with femtosecond pulses and different pulse energies, repetition rates, scanning speeds and number of scans.

Analysis of processing efficiency, surface, and bulk chemistry, and nanomechanical properties of the Monel® alloy 400 after ultrashort pulsed laser ablation

“…In calculations, the ablation depth l z for fully ablated regions (regions 1 and 2) is the average ablation depth obtained from measurements from top surface to bottom (where the average reference line is drawn on it) on the ablated cavity. For regions not fully ablated (regions 3 and 4), the ablation depth l z is obtained from cross-section profiles of the V-shaped cavity [31]. In this case, the maximum depth at the centre of the V-shaped profile is used as the ablation depth l z .…”

“…In this case, the maximum depth at the centre of the V-shaped profile is used as the ablation depth l z . The shape of micro-grooves was assumed to be perfectly V-shaped [31] for the sake of simplification in the calculation.…”

Bridging additive and subtractive manufacturing

“…The AddSub method can be used to create not only smooth walls, but also narrow structures within the part with extremely high aspect ratios (depth to width). Fabrication of small structures by machining with ultrafast lasers is strictly limited to aspect ratios in the lower twodigit range due to physical limitations of the fluence in the tip of the groove [9] or hole [10]. In the case of combined additive and subtractive processing, however, only the thickness of the previously melted layer needs to be drilled or cut.…”

Effect of Surface Roughness on the Surface Texturing of 316 l Stainless Steel by Nanosecond Pulsed Laser

“…φ th-sa of the samples (≈ 7 J/cm 2 ) was lower than the theoretical ablation fluence threshold th(Theo−e) (11.168 J/cm 2 ) that was calculated using Eq. 11 [26,31,58,62,74,75]: This is due to the explosive phase producing extra ablation material than the simple vaporising of the material. The explosion of the bubble provokes an increase of the amount of removed material owing to the ejection of the molten material, which is typical of the phase explosion [55].…”