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Texturing can be used to functionalize the surface of plastic parts and, in particular, to modify the interaction with fluids. Wetting functionalization can be used for microfluidics, medical devices, scaffolds, and more. In this research, hierarchical textures were generated on steel mold inserts using femtosecond laser ablation to transfer on plastic parts surface via injection molding. Different textures were designed to study the effects of various hierarchical geometries on the wetting behavior. The textures are designed to create wetting functionalization while avoiding high aspect ratio features, which are complex to replicate and difficult to manufacture at scale. Nano-scale ripples were generated over the micro-scale texture by creating laser-induced periodic surface structures. The textured molds were then replicated by micro-injection molding using polypropylene and poly(methyl methacrylate). The static wetting behavior was investigated on steel inserts and molded parts and compared to the theoretical values obtained from the Cassie–Baxter and Wenzel models. The experimental results showed correlations between texture design, injection molding replication, and wetting properties. The wetting behavior on the polypropylene parts followed the Cassie–Baxter model, while for PMMA, a composite wetting state of Cassie–Baxter and Wenzel was observed.

In the present work, a novel algorithm for the continuous projection of point triangles belonging to a triangle mesh is presented. The algorithm uses the normals defined at the vertices of the triangle to perform the projection. The direction of projection is not chosen a priori but depends on the point to be projected: the proposed algorithm, named Fast Continuous Projection method (FCP) lets the projection direction vary continuously on the mesh. Moreover, the direction is coherent with the original surface that is approximated with the triangle mesh. An optimized version of the algorithm is also presented: this uses pre-evaluated matrices to reduce the calculation time. This algorithm can be effectively used when a large set of points has to be projected on a coarse mesh as, for example, to generate the scanning vectors for laser engraving/milling.

This letter presents a 3-D-printed piezoelectric microphone with enhanced voltage sensitivity. The sensitivity is improved by a combination of a single-pillar mechanical design and a specific polyvinylidene fluoride (PVDF)-film electrode patterning. The moving part of the mechanical structure and the chassis are 3D-printed as a single unit and trimmed by laser cutting, allowing for a simple fabrication of the device. The measured sensitivity of 1 mV/Pa (±6 dB) in the bandwidth 500–2500 Hz agrees with simulations, showing an improvement over similar pillar-based piezoelectric sensor solutions. The sensitivity performance is shown to be comparable to existing microphones with different technologies. The microphone is also characterized by excellent linearity within the measurable range. 3D-printing technique can thus be adopted for the manufacturing of low cost and highly customizable microphone sensors.

In injection molding, high pressure is required to fill the mold, due to the high viscosity of thermoplastic polymers, the reduced thickness of the cavity and the low mold temperature. In this work, we investigate the functionalization of mold cavities for Injection Molding by means of Laser-Induced Periodic Surface Structures (LIPSS) generated on the ground surface of AISI 420 stainless steel through a picosecond laser. The LIPSS formation is examined with reference to the process parameters, highlighting how they affect the generated pattern. The improvements of the functionalized mold surface on the Injection Molding process are experimentally characterized and discussed. In particular, the slipping of molten PET was investigated as a function of nano-structuring orientation and injection velocity. The results demonstrate that LIPSS parallel to flow induce strong wall slip of the polymer melt, allowing a maximum reduction of the injection pressure of 10%.

A coaxial high-pressure gas jet is normally used to assist and enhance laser cutting quality and capability. However, the gas nozzles are mostly of conical type causing the deterioration of the dynamic characteristics of the exit jet. In this research, the effect of both nozzle type and nozzle dimensions on the uniformity and behavior of the exit jet has been investigated. A total of three different supersonic nozzles have been designed in accordance to gas dynamics theory and manufactured using wire electrical discharge machining (WEDM). The exit jet patterns from these supersonic nozzles and a reference conical nozzle have been numerically modeled and compared with the experimental observations made through Schlieren visualization. The experimental results are found to match and hence validate the simulations. It is concluded that the exit jet from the supersonic nozzle is marked by uniformity, better dynamic characteristics, and longer effective exit jet length compared with conical nozzle.

Surface structuring of medical implants has been shown to reduce the rejection rate of medical devices inserted inside living tissue. Several studies have shown that by texturing the surface of medical implants at micro/nanoscale it is possible to foster cell adhesion. The surface texturing of medical devices poses many challenges in terms of cost and time when the nano texturing process is performed directly on the part surface. A viable solution for mass production of polymer based surface enhanced medical devices is achieved via injection molding. However, nano structuring of micro injection molding molds, requires techniques enabling processing of complex surfaces, small curvature radii and with high aspect ratios. Furthermore the accessibility of all surfaces to be structured and the processing time are the main concerns and limiting factors on the selection of the structures dimensions and geometries. In this work, two different process chains are analyzed for the nano structuring of a bone micro plug. The first method relies on a chemical deposition process in order to produce a semi random structure on the entire mold surface of the medical component. The characteristic size of the structures is controlled by acting on the deposition parameters. The second process, relies on laser structuring of the mold components by producing Laser-Induced Periodic Surface Structures (LIPSS).The two process chains are compared and an evaluation of the applicability in different production scenarios presented, with specific focus on surface accessibility, nano structures uniformity and applicability to surfaces with complex geometry

In the present work, the generation of Laser Induced Periodic Surface Structures (LIPSS) by using femtosecond laser source is investigated in the surface texturing of Ti grade 5 dental implants. The proposed procedure permits a fast treatment of dental implants characterized by complex shape through the combined and synchronous use of a galvo scanner and of workpiece movements. The obtained surface micro- and nanostructures are characterized from a morphological point of view while in-vitro essays are performed to evaluate cellular proliferation. The results indicate the effectiveness of the LIPSS as method to increase cell viability and the efficiency of the proposed procedure to treat complex geometries as dental implants.

Laser-Induced Periodic Surface Structures (LIPSS) holds great potential for regenerative biomedicine. Creating highly precise LIPSS enables to generate biomimetic implant surfaces with improved properties. The present study focuses on the fabrication and investigation of laser-treated stainless steel samples with applied linear LIPSS patterns with grooves made by means of a picosecond laser system using wavelengths of 1064 nm and 532 nm. To investigate properties of the laser-treated surfaces and to understand the basics of cell-surface interactions between the LIPSS and human Umbilical Cord Mesenchymal Stem Cells (UCMSC), flat stainless steel samples with various applied nanopatterns were used. Such LIPSSs demonstrated higher surface roughness, good biocompatibility, lower wettability and higher corrosion resistance compared to the untreated (polished) specimens. The surface roughness of laser-treated samples was in microscale that enabled adhesion and migration of endothelial cells, thus increasing the likelihood for endothelialisation. This thereby could reduce the chances for the development of Late Stent Thrombosis (LST) and In-Stent Restenosis (ISR). Furthermore, laser textured surfaces demonstrated an environment supportive for cell attachment, proliferation and alignment with the nanogroves. Therefore, application of the biomimetic nanopatterns could help to overcome frequent post-surgery complications after the stent implantation.

The operating pressure of gas-assisted laser cutting and the resulting exit jet pattern is one of the most important process parameters in high-pressure laser cutting. Many studies have been done to illustrate the effect of this parameter on both laser cutting quality and laser cutting capability. However, most of these studies have been done using conical nozzles. In this paper, the exit jet from supersonic nozzle has been studied, analyzed, and simulated under three different operating conditions, namely desired design, under-expansion, and over-expansion to illustrate the effect of these operating conditions on the dynamic characteristics of the exit jet. Quasi 1-D gas dynamics theory has been used to calculate the desired design operating condition, and then an axisymmetric 2-D model has been created using the OpenFOAMⓇ Computational Fluid Dynamics (CFD) toolbox to simulate the gas-assisted laser cutting flow through the modeled supersonic nozzle. Finally, the proposed simulations have been validated by comparing the results with experimental observations reported in previous literature. The effect of the turbulent viscosity has been considered through the proposed model to better simulate real conditions. Moreover, the model has been optimized to be effectively used for engineering purposes. The simulation results are qualitatively consistent with the reported experimental measurements and they demonstrate that in the case of supersonic nozzles, the exit jet pattern is characterized by high uniformity, absence of Mach disks, and bounded shape for a long distance especially under the desired design operating conditions.

The CdTe quantum dots of different size are obtained in water and are dispersed within a polyvinyl alcohol polymer. The nanocomposite is then irradiated with different UV laser to test the reverse laser patterning conditions.

Modern ultrafast lasers are enabling better operative performances in micro and nano-fabrications of materials, benefited from their ease of use, robustness, and reliability. The purpose of this paper is to bridge the gap between the knowledge of ultrafast optics and the modern industrial applications. The paper introduces main phenomena in ultrafast laser-matter interactions by reviewing relevant theoretical models and simulation techniques. The operation of ultrafast lasers is based on nonlinear optics phenomena, fully described only in the framework of quantum-mechanics. Current trends in the development of modern ultrafast system are given. It also presents a review of the latest advances in ultrafast laser-based manufacturing processes, some of the most interesting industrial applications, and a discussion on future trends and challenges.

In the present work, a novel set of software tools for the rapid development of shoes and footwear is presented aimed at strongly reducing the design time and then the time-to-market of the products. These tools are mainly based on an implementation of Constrained Free Form Deformation techniques and on the use of modern surface scanning methods. The proposed approach allows, in many cases, to avoid the mathematical surface reconstruction and to quickly generate the complex geometries that CAM systems will process in order to generate the tool paths for mold manufacturing.

The uniformity of the exit jet pattern in high pressure gas-assisted laser cutting represents the main feature in order to achieve high cutting quality and capability. Therefore, the effect of both inlet stagnation pressure and nozzle geometry on the behavior of the exit jet has been investigated in this research. Quasi 1-D gas dynamics theory has been used to calculate the exact-design operating conditions for three different supersonic nozzles that were fabricated by means of Wire Electrical Discharge Machining. The jet flow through these nozzles has been numerically modeled and experimentally checked, using Schlieren visualization, under exact-design, over-expansion and under-expansion operating conditions coming to a good numerical-experimental agreement in terms of flow structure. As main result, the exit jet was found to preserve its uniform distribution with parallel boundaries and low divergence under the exact-design operating condition, differently to what observed for the others two conditions, especially for nozzle with small divergence angle.

In this paper a Point Inversion algorithm for NURBS volumes is presented. This algorithm is an extension to 3D of the classic Newton–Raphson iteration, thus implying the calculation of the NURBS volume partial derivatives. Explicit formulas for the derivatives are deduced and reported, in turn requiring the evaluation of the corresponding derivatives of the rational basis functions. Also these derivatives are inferred and shown together with some examples of applications. The method, applicable to any free-form shape NURBS volume is moreover compared with Fast Mapping, a novel approach presented here that, once applied to simple NURBS boxes give performance 20–50 times higher.

In injection moulding, high pressure is required to fill the mould, due to the viscosity of thermoplastic polymers, the reduced thickness of the cavity and the low mould temperature. In this work, significant pressure reduction was achieved inducing the slip of the polymer melt over the mould surface by means of Laser-Induced Periodic Surface Structures (LIPSS). In particular, the slipping of molten PET was investigated as a function of nano-structuring orientation and injection velocity. The results demonstrate that LIPSS parallel to flow induce strong wall slip of the polymer melt, allowing a maximum reduction of the injection pressure of 23%.

Highly regular laser-induced periodic surface structures (HR-LIPSS) have been fabricated on surfaces of Mo, steel alloy and Ti at a record processing speed on large areas and with a record regularity in the obtained sub-wavelength structures. The physical mechanisms governing LIPSS regularity are identified and linked with the decay length (i.e. the mean free path) of the excited surface electromagnetic waves (SEWs). The dispersion of the LIPSS orientation angle well correlates with the SEWs decay length: the shorter this length, the more regular are the LIPSS. A material dependent criterion for obtaining HR-LIPSS is proposed for a large variety of metallic materials. It has been found that decreasing the spot size close to the SEW decay length is a key for covering several cm2 of material surface by HR-LIPSS in a few seconds. Theoretical predictions suggest that reducing the laser wavelength can provide the possibility of HR-LIPSS production on principally any metal. This new achievement in the unprecedented level of control over the laser-induced periodic structure formation makes this laser-writing technology to be flexible, robust and, hence, highly competitive for advanced industrial applications based on surface nanostructuring.

In this paper, the effect of femtosecond laser nanotexturing of surfaces of Ti6Al4V and Zr implants on their biological compatibility is presented and discussed. Highly regular and homogeneous nanostructures with sub-micrometer period were imprinted on implant surfaces. Surfaces were morphologically and chemically investigated by SEM and XPS. HDFa cell lines were used for toxicity and cell viability tests, and subcutaneous implantation was applied to characterize tissue response. HDFa proliferation and in vivo experiments evidenced the strong influence of the surface topography compared to the effect of the surface elemental composition (metal or alloy). The effect of protein adsorption from blood plasma on cell proliferation is also discussed.

In this work, an analysis of the tribological performance of laser-induced periodic surface structures (LIPSS) treated X5CrNi1810 stainless steel was conducted. The approach followed by authors was to generate LIPSS-patterned circular tracks, composed of radial straight grooves with uniform angular periodicity. This permitted to measure the tribological properties in a pin-on-flat configuration, keeping fixed the orientation between the grooves and the sliding direction. A Stribeck curve was measured, as well as the consequent wear. A deep analysis of the sub-surface conditions after LIPSS generation was moreover performed using Focused Ion Beam (FIB) cross-section.

In the present work, the surface of Ti-6Al-7Nb samples was patterned with Laser Induced Periodic Surface Structures in order to improve biocompatibility, increase tissue ingrowth and decrease bacterial adhesion and inflammatory response for applications in dental and orthopedic implants. Polished and sandblasted disks 10 mm in diameter were treated generating LIPSS under two different sets of parameters. The surface morphology and chemistry were investigated both by secondary electrons imaging, EDS analysis and Atomic Force Microscopy. Primary rat osteoblast culture (passage 2) was used to assess cell toxicity and biocompatibility. Alamar Blue assay was used to access cell viability and proliferation on day 1, 3 and 7. The difference between cell adhesion on polished and sandblasted surface as well as between polished and LIPSS-modified surface are described and discussed.

The aim of the present work was the assessment of the impact of deep-rolling and shot-peening performed in the underhead and in the unthreaded shank of two high strength screws (36 NiCrMo and 42 CrMoV) for fatigue life enhancement. The experimental campaign consisted of six combinations, including the non-treated state. The aforementioned treatments were evaluated alone or with shot-peening performed after deep-rolling in the underhead fillet of the screws. Deep rolling was carried out at the optimal rolling force, whereas two shot diameters were considered for shot-peening (Z100 and UFS70). The results have been evaluated in terms of fatigue limits and factor effects have been assessed by marginal mean plots.

In this brief review the advances on Direct Laser Patterning (DLP) for the synthesis of photo-luminescent semiconductor quantum dots (QDs) belonging to II-VI groups, especially in solid state using laser-assisted conversion are reported and commented. The chemistry of the precursor synthesis is illustrated because it is a crucial step for the development of the direct laser patterning of QDs. In particular, the analysis of cadmium (bis)thiolate and cadmium xanthates precursors after thermal and laser treatment is examined, with a special focus on the optical properties of the formed QDs. The second part of the review examines how the laser parameters such as the wavelength and pulse duration may regulate the properties of the patterned QDs. The DLP technique does not require complex laser systems or the use of dangerous chemical post treatments, so it can be introduced as a potential method for the patterning of pixels in quantum dot light emitting diodes (QD-LEDs) for display manufacturing.

The synthesis of colloidal photo-luminescent semiconductor quantum dots (QDs), belonging to II-VI groups, even from single source precursors is presented. Since three decades their synthesis has been pursued implementing new and easier synthetic conditions that standardize their production. In this work is reported the production of luminescent of CdS QDs in a polymeric film induced by laser processing (www.miledi-h2020.eu/). A film of PMMA doped with two types of precursors (cadmium xanthates) is irradiated with an UV laser source with different energy doses. The structured film will then be observed with confocal fluorescent microscope. The interesting results shows that the two different xanthates display a different behavior under the laser source even if their absorption spectrum is similar. The second interesting result is that the effect of the laser is the production luminescent pattern only for certain fluences and that the same film treated with the temperature did not show any luminescence.The synthesis of colloidal photo-luminescent semiconductor quantum dots (QDs), belonging to II-VI groups, even from single source precursors is presented. Since three decades their synthesis has been pursued implementing new and easier synthetic conditions that standardize their production. In this work is reported the production of luminescent of CdS QDs in a polymeric film induced by laser processing (www.miledi-h2020.eu/). A film of PMMA doped with two types of precursors (cadmium xanthates) is irradiated with an UV laser source with different energy doses. The structured film will then be observed with confocal fluorescent microscope. The interesting results shows that the two different xanthates display a different behavior under the laser source even if their absorption spectrum is similar. The second interesting result is that the effect of the laser is the production luminescent pattern only for certain fluences and that the same film treated with the temperature did not show any luminescence.

Authors would like to correct the error in article title. Word “for” in the title has been inadvertently changed to “ior”. Correct version of article title updated here.

In the present work, three different supersonic nozzles were designed and manufactured to operate at various stagnation pressures during laser cutting. Several cutting experiments were performed on stainless steel samples of various thicknesses (2, 4, 6 mm) using a fiber laser of 3 kW with a head adapted to fit with both the proposed supersonic nozzles and a commercial reference conical nozzle. The flow through these nozzles was numerically modeled and compared with the Schlieren visualization measurements. The mass flow rate, the Mach number, and the pressure distributions were selected in detail in order to analyze the dynamic characteristics of the exit jet and to comparatively assess the achieved cutting quality (roughness perpendicularity) and capability (maximum thickness, cutting speed). The numerical and the experimental results were found to be in high agreement in terms of the flow structure and mass flow rate. In addition, a significant reduction of the assistance gas consumption of up to 65% on average was achieved by using supersonic nozzles as opposed to conical ones, accompanied with the decrease of the operating pressure and the increase of the cutting speed.

Picosecond laser-induced periodic surface structures (PLIPSS) have been fabricated on surface of Si in uniform and burst-mode regimes at a high speed. The effects of burst-mode respect to uniform one are examined in term of chemical, mechanical and morphological properties.

The microstructure, phase composition and microhardness of multilayered Ti/Al, Ti/Cu, Ti/Fe and Ti/Zr condensates produced on stainless steel substrates via vacuum-arc evaporation of pure metals were studied. The sublayer periods (Λ) were regulated in the range 80–850 nm by varying the vacuum discharge current and the duration of the successive depositions of metallic plasma onto the substrates while maintaining the total deposition time constant. The regularity of the obtained nanostructures was investigated by scanning and transmission electron microscopy while phase compositions were identified with X-ray diffraction (XRD) analysis in order to evidence the presence of interdiffusion and the amount of intermetallics. Condensates cross sections were mechanically characterized by means of microhardness tests. Measurements were correlated to the periods and to the presence of intermetallics.

Laser Texturing and Laser Engraving of free form surfaces are interesting alternative to EDM and micro milling in the fabrication of moulds and dies. The material removal rate of this process is typically very low and the maximum working area is limited by the maximum travel range of the galvanometric scanning head and also by the maximum deflection of the scanner or the surface curvature. As a consequence, in order to manufacture large or free form surfaces, a set of placements of the scanning head respect to the work piece must be calculated and controlled by the CNC. The number of these placements can be quite high due the small amount of material removed in each of them and the non-operative time spent to move the scanning head can be relevant compared to the overall time. In this work a method based on the solution of the Traveling Salesman Problem is proposed with the aim to optimise the number of displacements of the scanning head and generally in order to reduce the number of movement of the numerically controlled axes. The method that takes into account both the architecture and the dynamic characteristics of a 5 axis CNC system was implemented in the CALM (Computer Aided Laser Manufacturing) software used to program the laser path for part texturing and applied in industrial cases.

Surface nano- and microstructuring with additive and subtractive lithography techniques are commonly used in nanotechnology and photonics, while nanoimprint lithography and nanosphere lithography are used for creating periodic structures for plasmonics applications. Single step, maskless optical patterning techniques also exist, notably multi-beam interference based techniques and Laser Induced Periodic Surface Structures (LIPSS). LIPSS have been demonstrated on metals, semiconductors, dielectric surfaces, polymers, and have been used in various applications including solar cells, plasmonics, colorizing metals, wettability and tribology applications. Until recently these optical techniques lacked the long-range periodicity required for some of the applications. Moreover, conventional optical lithography techniques require complex masks, while e-beam lithography and ion-beam lithography require expensive equipment. Recently, a method for direct writing of highly-regular LIPSS (HR-LIPSS) was developed for creating uniform approach overcoming all aforementioned lithography problems [1].

In this work the effect of femtosecond Yb fiber laser irradiation on Ti6Al4V titanium alloy is assessed. An extensive experimental campaign is carried out to survey surface properties through the use of SEM, AFM, EDS mapping and contact angle measurements. It is shown that the generation of uniform nanoscale laser induced periodic surface structures (LIPSS) allows to tailor surface properties and improves adhesive bonding with epoxy resin. The potential of the technique to improve the durability of the joints against accelerated aging is also evaluated.

We report on periodic, homogeneous nanoripples fabricated on stainless steel (SS), copper (Cu), and aluminum (Al) substrates using an ytterbium pulsed femtosecond laser. These structures called laser induced periodic surface structures (LIPSS) are processed at a relatively high-speed and over large areas. This paper investigates the effect of LIPSS on a wettability behavior of SS, Cu, and Al surfaces. It is shown that nanoripples significantly influenced the wettability character of these metals turning them from hydrophilic to hydrophobic behavior.

Highly-regular laser-induced periodic surface structures essentially change surface properties of treated surfaces. Here, effect of HR-LIPSS on optical, tribological, mechanical and wetting properties of stainless steel were systematically investigated.

Plasmonic properties of gold nanoparticles self-assembled on silicon surfaces are significantly enhanced by a periodic surface ripples induced by ultrashort laser pulses. The nanostructured surfaces open new perspectives for production of photonic and plasmonic-sensor elements.

Sub-MHz repetition rate femtosecond laser pulses produce extremely regular periodic surface structures on silicon surface due to competition between ultrafast heating and electron-emission. They allow manufacturing of novel devices for solar, optoelectronic, and biomedical applications.

New method based on HR-LIPSS for diffraction grating formation on preliminary fabricated p-n junction on Si substrate are suggested. This allows to produce surface plasmon-polariton photodetectors based on periodically corrugated thin metal plasmon-carrying films.

Femtosecond laser pulses of sub-MHz repetition rate induce highly regular periodic surface structures on silicon by combining electron emission and ultrafast heating. They are favorable for photovoltaic, optoelectronic, and biomedical applications.

Femtosecond laser-based Nonlinear Laser Lithography (NLL) was applied to AISI 316L stainless steel, which requires surface modification to achieve satisfactory tribological behaviour. NLL advances over the well-known Laser Induced Periodic Surface Structures (LIPSS) in terms of uniformity and long-range order of high speeds, over large areas. A galvanometric scanner head was used for an high production rate. Dry and lubricated sliding tests, considering different orientations of the nanotexture showed that COF values after NLL treatment are significantly lower. In lubricated tests, COF values of NLL-treated surfaces are nearly half the values of untreated surfaces, whereas the difference further increases when measured in dry conditions, where the orientation of the surface texturing influences the results.

Silicon is one of the most abundant materials which is used in many areas of modern research and technology. A variety of those applications require surface nanopatterning with minimum structure defects. However, the high-quality nanostructuring of large areas of silicon surface at industrially acceptable speed is still a challenge. Here, we report a rapid formation of highly regular laser-induced periodic surface structures (HR-LIPSS) in the regime of strong ablation by infrared femtosecond laser pulses at sub-MHz repetition rate. Parameters of the laser-surface interactions and obtained experimental results suggest an important role of electrostatically assisted bond softening in initiating the HR-LIPSS formation.

The growing need of lightweight components determined a large exploitation of non metallic materials such as polymers, fibres and elastomers in the industrial production with a consequent request of specifically optimized manufacturing processes. The high optimization demands in terms of cost, weight and productivity of the modern markets determined a growing interest towards hybrid components in which two or more different materials coexist in order to achieve specifically optimized characteristics. According to these considerations the work proposed in this article is aimed at experimentally evaluate the feasibility of joining processes between metal and plastic components by means of the exploitation of a laser source. The metallic material involved in the experimental trials is AISI 304 stainless steel joined in an overlapping configuration with several different polymers: PA66, glass fibre reinforced PA66, carbon fibre reinforced PA66. The laser source involved in this activity was a 100 W CW diode source equipped with a three axis cell. In order to evaluate the results of the joining process a tensile test was carried out on the obtained specimens.

This paper presents a model able to predict the austenization of hypo-eutectoid steels during very fast heat cycle such as laser hardening. Laser surface hardening is a process highly suitable for hypo-eutectoid carbon steels with carbon content below 0.6% or for low alloy steels where the critical cooling rate is reached by means of the thermal inertia of the bulk. As proposed by many authors, the severe heat cycle occurring in laser hardening leads to the pearlite to austenite microstructures transformation happening to a temperature much higher than the eutectoid temperature A c 1 and, afterwards, all the austenite predicted during the heating phase become martensite during quenching. Anyway, all these models usually generate a predicted hardness profile into the material depth with an on–off behavior or very complicated and time consumed software simulators. In this paper, a new austenization model for fast heating processes based on the austenite transformation time parameter I p → a is proposed. By means of the I p → a parameter it is possible to predict the typical hardness transition from the treated surface to the base material. At the same time, this new austenization model also reduces the calculation time. I p → a was determined by experimental tests and it was postulated to be constant for low-medium carbon steels. Several experimental examples are proposed to validate the assumptions and to show the accuracy of the model.

In this study an application of free form deformation for the editing of clouds of points or tessellated surfaces representing industrial parts is presented. The application is based on an efficient implementation of NURBS based free form deformation and the implementation of functions for imposing constraints to position, directions and curvatures of embedded objects. The developed functions permit the direct manipulation of triangulated surfaces eliminating the surface reconstruction stage, reducing the time requested in the reverse engineering process and, at the end, reducing the time to market.

This article illustrates the development of a complete and exhaustive mathematical model for the simulation of laser transformation hardening of hypo-eutectoid carbon steels. The authors propose an integrated approach aimed at taking into consideration all the phenomena involved in this manufacturing process, with particular attention to implementing easy mathematical models in order to optimize the trade-off between the accuracy of the predicted results and the computational times. The proposed models involve the calculation of the 3D thermal field occurring into the workpiece and predict the microstructural evolution of the target material exploiting an original approach based on the definition of thermodynamic thresholds, which can be considered as a physical constant of the material itself. Several parameters and phenomena are taken into consideration in order to accurately simulate the process: laser beam characteristics, fast austenization of the steel, and tempering effect due to mutually interacting beam trajectories. The accuracy of the model is presented by means of hardness comparisons between hardness predictions and measurements in single and double paths surface treating of AISI 1040.

Laser shock peening is a well-known technology able to enhance the fatigue life of mechanical components by means of the introduction of residual stresses on their surface. These stresses are induced by means of the recoil pressure caused by the abrupt expansion, in a confining medium, of a laser-vaporized coating layer. If high power densities are used the recoil pressure can be high enough to induce compressive residual stresses on the target surface and to modify its mechanical properties. These mechanical properties can be predicted if the recoil pressure of the ablating layer is determined. In this paper the influence of the laser pulse shape on the recoil pressure is determined by means of a proper modeling of the whole process and the difference between cold" and warm" laser shock peening is pointed out.

Date of Conference: 21–25 June 2015 Conference name:2015 European Conference on Lasers and Electro-Optics - European Quantum Electronics Conference The production of nanostructures on different materials attracts much attention in different fields of manufacturing as a result of increased availability, affordability and technical capability of laser-based methods [1,2]. However, some shortcomings such as relatively low speed of processing, problems with material control, and lack of uniformity and/or repeatability over large areas continue to limit their practical adaptation.

In this study a series of procedures were implemented to compare acquired surfaces with the nominal data or to directly compare different scanned surfaces. In particular a morphological evaluation algorithm based on the extended Gaussian curvature (EGC) and a method to compare features based on aggregate normal orientation are presented. To perform the comparing feature method a simple procedure for segmentation was developed. The main characteristic of the two methods is robust behavior referring to the scan orientation. The procedures were implemented as software modules in a graphic environment.

Recently, several studies have demonstrated that a variety of metallic materials, including aluminium-based composites, can exhibit superplasticity at relatively high strain rates (≤10−2s−1). High strain rate superplasticity (HSRS) is very attractive for commercial applications, mainly for materials difficult to shape or machine with conventional techniques, such as metal matrix composites. In this work, the possibility of achieving HSRS in a recently developed composite with an AA6013 matrix reinforced with about 20 vol % of SiC particles (AA6013/20/SiCp) was studied. Uniaxial tensile tests were carried out at high strain rates (1 × 10−1s−1 and 1 × 10−2s−1) and in a temperature range between 520 and 590°C. A maximum elongation-to-failure of 370 per cent was obtained at 560°C with a strain rate of 1 × 10−1s−1. This temperature is very close to the temperature at which melting of the composite starts. Scanning electron microscopy (SEM) analyses of fracture surfaces in the optimum superplastic condition showed the presence of filaments, the formation of which generally related to the presence of a liquid phase at the grain boundaries and/or at the interfaces.

Lithium ion battery electrodes have been exposed to 1064nm nanosecond pulsed laser irradiation with pulse energy in the range 8μJ – 1mJ and fluence in the range 3.2 – 395J/cm2. Experiments have been executed at translational velocities of 100mm/s and 1m/s, allowing individual characterization of the graphite and lithium metal oxide coatings of the copper anode and aluminum cathode, respectively, as well as that of the complete multi-layer structures. A 3D optical profiler has been utilized to measure the incision depth of all samples and allow observation of the process quality. At high velocity, partial or complete removal of the upper coating layers was achieved with little or no impact on the underlying metallic layers. At low velocity, complete cuts were possible under certain conditions, with process efficiency found to be almost entirely governed by the response of the metallic layers. While the coating layers of each electrode exhibited different responses than the metallic layer, the influence of the latter was found to be dominant for cutting operations. Shorter pulses with fluence in the range 30 – 60J/cm2 were found to lead to optimum process outcomes with the employed laser source.Copyright © 2014 by ASME

A new process, based on ring spot geometry, is presented for laser surface hardening of large cylindrical components. The proposed technique leads to a very hard, deep and uniform hardened layer along the entire work piece surface without introducing a tempered zone, making the process very attractive compared to conventional induction hardening that exhibits both low energy efficiency and poor flexibility. A complete physical model is presented for the process, together with a study of the influence of process parameters on the final outcome. The results of an extensive validation campaign, carried out on AISI 1040 specimens, are also reported.