On the welding of different materials by diode laser

In technical literature, there are few papers about the use of diode lasers in material processing and particularly in metal welding. In this paper, different materials, according to specific and particular industrial needs and requests, have been tested with a welding process by a diode laser, emitting a 808 nm laser radiation. Beads on plate have been studied. The goal was to evaluate the maximum weldable thickness and define the best process parameters for each material. The experimental evaluation has been carried out considering the following parameters: power level, welding speed (WS), shielding gas, gas nozzle and orientation of the focused elliptical spot as to the welding direction

Laser cutting of different polymeric plastics (PE, PP and PC) by a CO2 laser beam

Thiswork investigates the application of theCO2 laser cutting process to three thermoplastic polymers, polyethylene (PE), polypropylene (PP), polycarbonate (PC) in different thicknesses ranging from 2 to 10 mm. The process parameters examined were: laser power, range of cutting speed, type of focusing lens, pressure and flow of the covering gas, thickness of the samples. Furthermore, the values of kerf widths on top (Lsup) and bottom (Linf ) thicknesses, the melted transverse area, the melted volume per unit time and surface roughness values (Ra) on cut edges were also measured

Influence of Eta-Phase on Wear Behavior of WC-Co Carbides

Cemented carbides, also known as Widia, are hard metals produced by sintering process and widely used in mechanical machining. They show high cutting capacity and good wear resistance; consequently, they result to be excellent materials for manufacturing cutting tools and sandblast nozzles. In this work, the wear resistance of WC-Co carbides containing Eta-phase, a secondary phase present in the hard metals when a carbon content deficiency occurs, is analyzed. Different mixtures of carbide are prepared and sintered, with different weight percentages of carbon, in order to form Eta-phase and then analyze how the carbon content influences the wear resistance of the material. This characterization is carried out by abrasive wear tests. The test parameters are chosen considering the working conditions of sandblast nozzles. Additional information is gathered through microscopic observations and the evaluation of hardness and microhardness of the different mixtures. The analyses highlight that there is a limit of carbon content below which bad sintering occurs. Considering the mixtures without these sintering problems, they show a wear resistance depending on the size and distribution of the Eta-phase; moreover, the one with high carbon content deficiency shows the best performance

Laser Marking of Titanium Coating for Aerospace Applications

Abstract In the aerospace industry, in order to ensure the identification and the traceability of the products, high repeatability, non-invasive and durable marking processes are required. Laser marking is one of the most advanced marking technologies. Compared to traditional marking processes, like punches, microdot, scribing or electric discharge pencil etcher, laser marking offers several advantages, such us: non-contact working, high repeatability, high scanning speed, mark width comparable to the laser spot dimension, high flexibility and high automation of the process itself. In order to assure the mark visibility for the component lifetime, an appropriate depth of the mark is required. In this way, a stable behaviour is ensured also when the component operates in aggressive environments (i.e. in presence of oxidation, corrosion and wear phenomena). The mark depth is strongly affected by the laser source kind and by the process parameters, such us average power, pulse frequency and scanning speed. Moreover, an excessive mark penetration could cause stress concentrations and reduce the fatigue life of the component. Consequently, an appropriate selection of the process parameters is required in order to assure visibility and to avoid excessive damage. Cold Spray Deposition (CSD) is a relative new technology that allows to produce surface coatings without significant substrate temperature increasing. In aeronautics fields this technology is useful to coat materials sensible to temperature, such as solution tempered aluminum alloy, with a titanium layer. Aim of the work is to characterize the laser marking process on CSD Ti coating, in order to study the influence of the laser marking process parameters (pulse power and scanning speed), on the groove geometry of the marking. The experimental marking tests were carried out through a 30 W MOPA Q-Switched Yb:YAG fibre laser; under different process conditions. The groove geometry was measured through a HIROX HK9700 optical microscope. The results showed the effectiveness of the laser process to produce high quality marks on the titanium layer. Moreover, a correlation between the process parameters and the mark's geometry was clearly observed

METODICA PREDITTIVA PER LA VALUTAZIONE DEI DIFETTI SU LAMINATI SOTTILI IN LEGA AA3005 PER IL SETTORE PACKAGING DERIVANTI DA INCLUSIONI SOLIDE NEI BAGNI DI FUSIONE

Nel presente lavoro si è cercato di mettere a punto una metodica di prova per l’ individuazione predittiva deimicrofori nei laminati sottili in lega di alluminio sin dalla fase di fusione delle placche (cioè a monte del ciclo difabbricazione.)Mettendo in relazione ripetutamente i risultati del “test PREFIL®” [1], effettuato nella fase di colata delmetallo, in grado di quantificare la presenza di inclusioni solide e ossidi, con i risultati, in termini di microfori,rilevati sul laminato al termine della laminazione a freddo mediante l’utilizzo di un rilevatore ottico laser,è stato possibile ricavare relazioni abbastanza affidabili circa la previsione delle difettosità sul laminato aspessore finale, già dalla fase di colata

Ti6Al4V sheets lap and butt joints carried out by CO2 laser: mechanical and morphological characterization

This research work deals with the most commonly used titanium alloy, Ti6Al4V. Lap and butt laser welding processes were studied and tested by a CO2 laser system using two covering gases (He and Ar) with different welding covering gas nozzles, gas pressure and flow rates. A metallographic analysis of the cross-sections of welded specimens was carried out in order to measure the morphological characteristics of the welded joint, and micro-hardness and tensile tests were performed to complete the mechanical characterization

On the welding of different materials by a diode laser

On the welding of different materials by a diode lase

Laser cutting of different polymeric plastics (PE, PP and PC) by a CO2 laser beam

This work investigates the application of the CO2 laser cutting process to three thermoplastic polymers, polyethylene (PE), polypropylene (PP), polycarbonate (PC) in different thicknesses ranging from 2 to 10 mm. The process parameters examined were: laser power, range of cutting speed, type of focusing lens, pressure and flow of the covering gas, thickness of the samples. Furthermore, the values of kerf widths on top (Lsup) and bottom (Linf) thicknesses, the melted transverse area, the melted volume per unit time and surface roughness values (Ra) on cut edges were also measured

Employment of the fuzzy logic modelling in the quenching of steel rods for reinforced concrete after hot rolling

Udine, Ital