This study evaluated the feasibility of laser-textured biomimetic designs for cutting tools to investigate the effects of laser-textured tools combined with cryogenic cooling using liquid nitrogen (LN2) on the tool-chip interface, built-up edge (BUE) formation, and friction during Al-MMC machining. This study involved selecting a biomimetic design, converting it into a textured cutting tool, evaluating the coefficient of friction (CoF) and cutting forces on the textured surface under dry conditions, and using cryogenic LN2 as a coolant with the textured tool. Femtosecond lasers were used to precisely create biomimetic surfaces near the rake face edge without compromising tool integrity. The pin-on-disc method revealed no significant CoF difference between plain and textured tools or among textured tools within the determinate pin load impact. Dry machining tests showed a higher CoF than the pin-on-disc method owing to strong workpiece material adhesion. Cutting force analysis under dry and textured conditions showed negligible effects on aggregate force components, although textured tools had a higher feed force than untextured ones. Cryogenic cooling with plain tools reduced BUE height, TCClength, and TCCarea compared to dry conditions. Textured tools in dry conditions increased BUE height and acted as chip breakers, reducing TCClength and TCCarea compared to dry plain tools. Most textured tools with cryogenic cooling reduced the BUE height, TCClength, and TCCarea compared to their dry-textured counterparts. The findings suggest that combining biomimetic textured cutting tools with cryogenic machining is a promising approach for sustainable manufacturing of Al-MMC's.

Short and ultrashort pulse lasers are increasingly used for cutting tool preparation. On the one hand, nanosecond lasers can ablate material very effectively but result in poor surface quality and material heat influence. On the other hand, femtosecond lasers are very precise tools with relatively low productivity. In this paper, a complex approach combining nanosecond laser roughing and femtosecond laser finishing is presented for effective sintered carbide ablation in one laser machine. The machining time was shortened by more than 74

Ultra-short pulsed laser ablation may be used for high-precision machining with very low thermal influence on the processed materials. Due to this reason, lasers are increasingly used for processing of advanced materials, such as titanium alloys, nickel-based alloys or steel, every year. In this study, four advanced technical materials were analysed and compared under femtosecond laser irradiation with three different wavelengths. The main laser-material interaction parameters were identified, namely the ablation threshold and removal efficiency parameters. Higher removal rates were found for Ti6Al4V alloy with all three harmonic wavelengths. To increase process productivity, a method of increasing the repetition rate and scanning speed was presented. With the maximum repetition rate, the productivity increased five-fold with a similar removed depth and surface quality. Finally, the suitability of the identified parameters with regard to quality and productivity was demonstrated for fabrication of two complex structures – honeycomb and dot – which has the potential to improve friction properties of advanced materials.

Coatings are used in many industrial applications as a protective barrier, improving component properties such as friction, wear resistance, and thermal resistivity. When components become worn, any coatings must be thoroughly removed before performing repairs. Laser stripping is a relatively new technology developed for the entire coating removal. So far, only laser stripping of the entire coatings has been discussed in literature, but its application in selective de-coating layer by layercan extend the usage of this technique. Herein, we describe a new method of selective and precise laser de-coating layer by layer in layer thickness lower than 0,15 μm and demonstrate tise technique on two coatings, namely AlTiN and diamond-like carbon. This method is based on ablation threshold measurement and the application of low laser beam fluences for selective de-coating, layer by layer, in a defined pattern. Then the average minimal removals per layer were estimated for both coatings using first and second harmonic wavelengths. Finally, the usage of this method was proved by chemical analysis of the de-coated areas. The presented method can extend the use of laser coating stripping from actual removal of whole coatings to new areas, for example thickness measurement or inter-layer inspection of coatings.

This study outlines the methodology of the new approach of laser stripping technique in functional surfaces of monolithic cutting tools. Starting from the initialization test of the coating thickness using a laser calotest including beam-material interaction test, through the introduction of the main geometrical elements necessary for the analysis of the tool, the study discusses segmental laser stripping including its evaluation, where the effects of different segment modifications (overlapping, resizing, rotation or reordering) were investigated. The influence of the presented technology on the microgeometry of the tool was beneficial from several points of view: the area around the cutting edge can be influenced by the polarization of the laser beam and the resulting radius values show no negative influence of the substrate by the laser.

Laser polishing process is a promising technology for post-processing of complex parts prepared by additive manufacturing. In this study, the nanosecond laser polishing process was employed to improve a surface roughness of SLM (selective laser melting) prepared 316 L stainless steel with different part orientation (0°, 15°, 45°, 75° and 90°) during construction. Afterwards, the changes of surface topography, morphology and the cross-sectional microstructure before and after laser polishing were investigated. Additionally, the study also focusses on the process of 3D printing, especially on material porosity after sintering process. The results obtained from computer tomography showed that the samples were well prepared, with porosity below 0.019%. After laser polishing, surface roughness represented by Sa and Sz values was reduced for all printed samples regardless to their construction angle with similar laser and scanning parameters. The maximum roughness reduction reaches more than 90% (from Sa = 9.8 µm to Sa = 0.77 µm). Moreover that, other surface analysis established the best conditions for laser polishing. Finally, from the cross-section, the microstructure analysis was done and thickness of melted layer, heat-affected zone followed by microhardness measurement was estimated. Except of one applied condition, all samples were very homogenic with no damages in intersection layer. Simultaneously, there were no changes in microhardness after laser process observed.

In this paper, a quick nanosecond laser micro structuring process was employed to change the surface wettability of Ti6Al4V alloy. The same laser structuring method was used throughout, but with varying input fluence. The laser processing parameters resulted in high surface melting. After laser treatment, four post-processing methods were used, namely high vacuum, low temperature annealing, storage in a polyethylene bag, and storage in ambient air. Subsequently, the water droplet contact angle was measured over a long time period of 55 days. The results show that the sample stored in ambient air remained hydrophilic. On the other hand, the sample post-processed in a vacuum chamber behaved hydrophobically with a contact angle of approximately 150°. Other post-processing did not lead to specific wettability behavior. After wettability testing, all samples were cleaned ultrasonically in distilled water. This cleaning process led to annulation of all obtained properties through post-processing. In summary, this paper shows that it is more important to study surface chemistry than topography in terms of effects on wettability. Moreover, surface wettability can be controlled by laser structuring, post-processing, and surface cleaning.

The lifetime and properties of cutting tools and forming moulds can be prolonged and enhanced by the deposition of hard, thin coatings. After a certain period of usage, the coating will deteriorate. Any remaining coating must be removed prior to successful recoating. Laser stripping is a fast and environmentally friendly coating removal method. In this paper, we present laser removal of two types of coatings deposited on a 1.2379 tool steel substrate, namely, an AlTiN coating with high hardness and a DLC C coating with a small coefficient of friction (COF). A powerful nanosecond laser was employed to remove the coating from the substrate with high efficiency, along with suitable residual surface roughness. Measurements were taken of surface roughness, removed depth, and working time on a stripped area of 1 cm(2). The samples were evaluated under a microscope, with a 3D profilometer, and by EDS chemical analysis. Successful removal of the coating was confirmed by optical analysis, but detailed chemical characterisation showed that about 30% of the coating element may remain on the surface. Moreover, a working time of less than 7.5 s per cm(2) was obtained in this study. In addition, it was shown that the application of a second low energy, high frequency laser beam pass leads to remelting of the peaks of the material and reduced surface roughness.