Processing of metal

Femtosecond lasers enable the production of complex shapes and features, while also providing the capability to perform black/white marking and coloring without the need for chemical additives.

Glass Metal Polymer Other materials
Metal

MHz burst usage in increasing femtosecond removal efficiency in aluminum, copper and stainless steel

Femtosecond processing of materials faces a significant challenge in terms of process throughput. There exists an optimal fluence value at which the most efficient material removal occurs. However, with high average power lasers, achieving this optimal fluence is difficult. In order to achieve the optimal fluence at higher powers, one is forced to increase the repetition rate to values where significant thermal accumulation occurs, often leading to degradation in processing quality. The optimal fluence can be achieved by using MHz burst mode, which splits the high-energy pulse into multiple sub-pulses, enhancing the efficiency of material processing, especially metals, compared to single-pulse mode.

In a recent study by A. Žemaitis et al., the FemtoLux 30 laser was used to optimize machining methods for aluminum, copper, and stainless steel. The researchers conducted material removal optimization by milling 110 cavities in a single metal sample, varying the pulse repetition rate and the number of pulses in the burst. Utilizing MHz burst mode allowed to achieve optimal fluences, resulting in not only high removal efficiency but also great surface roughness. Especially, removal efficiency and rate were increased by 18%, 44.5% and 37% for aluminum, copper and stainless steel accordingly, if compared to the single-pulse operation mode.

Efficiently laser milled aluminium Fresnel lens mould diameter 35 mm.

Efficiently laser milled aluminium Fresnel lens mould, diameter 35 mm: (a) optical photograph, (b) 3D height map and (c) 2D profile from the middle of the structure.

Courtesy of FTMC.

Results of processing various metal samples with MHz burst

MaterialRemoval efficiencyRemoval rateSurface roughnessNo. of pulses in burst
Aluminum7.0 µm3/µJ9.2 mm3/min1.7 µm10
Copper4.2 µm3/µJ5.6 mm3/min2 µm5
Steel3.9 µm3/µJ5.1 mm3/min1.7 µm10
MaterialRemoval efficiencyRemoval rateSurface roughnessNo. of pulses in burst

(a) Experimental setup; (b) optimisation of removal efficiency and rate for metals by variation of pulse repetition rate and number of pulses per burst; (c) correlation between removal efficiency and surface roughness; (d) different operation modes – single-pusle and MHz burst mode with indicated 3 pulses in burst mode.

Courtesy of FTMC.
Ablation FemtoLux

The ultrafast burst laser ablation of metals: Speed and quality come together
A. Žemaitis, U. Gudauskytė, S. Steponavičiūtė, P. Gečys, and M. Gedvilas, Optics & Laser Technology 180, 111458 (2024). DOI: 10.1016/j.optlastec.2024.111458.

Recommended products

FemtoLux

Industrial Femtosecond Lasers
  • 50 W / >300 µJ at 1030 nm
  • 20 W / >50 µJ at 515 nm
  • 10 W / >25 µJ at 343 nm
  • < 350 fs – 1 ps
  • Single shot to 4 MHz (AOM controlled)
  • MHz, GHz, MHz+GHz burst modes

Similar applications

Optical photograph of laser milled aluminium Fresnel lens mould, diameter 35 mm.
MHz burst usage in increasing femtosecond removal efficiency in aluminum, copper and stainless steel

Femtosecond processing of materials faces a significant challenge in terms of process throughput. There exists an optimal fluence value at which the most efficient material removal occurs.
Stainless steel cutting
Various metal type processing

Femtosecond lasers excel in machining metals, primarily due to their ultra-short pulse duration, which ensures superior processing quality with no burrs, minimal heat-affected zones, and high precision. Metals, especially thin metal foils, are integral to modern engineering and manufacturing. Femtosecond lasers enable the production of complex shapes and features in these materials.
Black marking of tweezers.
Black/color marking of metals

One of the largest applications of lasers is metal marking and coloring. Femtosecond lasers can structure the metal surface, making it rough and highly absorbent of incident light, resulting in high-contrast black markings. These markings not only provide high contrast but also exhibit strong resistance to environmental effects. Additionally, by gently heating metal surface and carefully managing the thickness of the oxide layer formed on the surface, specific colors can be achieved.
Grid surface texturing with LIPSS of nitinol
Metal surface texturing

It is possible to functionalize metal surfaces by creating intricate and complex geometries by irradiating the material with femtosecond pulses. Operating near ablation threshold energy levels allows the production of laser-induced periodic surface structures (LIPSS), which alter the metal’s surface properties, improving light absorption (black marking), adjusting wettability, enhancing tribology, and creating anti-bacterial surfaces.
Nitinol stent cutting.
Nitinol stent cutting

Femtosecond lasers are superior in cutting nitinol stents, a crucial application in the medical field due to the exceptional precision required. The ultra-short pulse duration of femtosecond lasers ensures superior processing quality, resulting in smooth edges, minimal burr formation, and low heat affected zones. This precision and quality is vital in manufacturing nitinol stents, which require intricate geometries and exact dimensions to function correctly within the human body.
All applications