1,721,158 research outputs found
Laser micro-welding of high carbon steels [Microsaldatura laser di acciai ad elevato tenore di carbonio]
No full textHigh carbon steels are commonly used in modern mechanical industry due to their good mechanical properties and to their relatively low cost. Unfortunately, when dealing with welding processes, these materials must be set aside because of their very high crack susceptibility and more refined and expensive steels must be taken into consideration, such as HSLA, DP and TRIP ones, thanks to their lower carbon equivalent and similar, or even better, mechanical properties. In micro-scale components industry the use of high carbon steels is also very common, in particular in precision mechanics, watch and MEMS industry. Considering the very low thicknesses typical of these components and the intrinsic welding difficulty related to the material, several studies stressed on the possibility to exploit nanosecond pulsed lasers in welding this kind of steels. These sources, taking advantage from the short duration of the pulse and from a repetition rate as high as I MHz, allow a very accurate control of the heat input delivered to the material and pave new ways in micro-welding of medium and high carbon steels. The present paper deals with the exploitation of a 20 W nanosecond pulsed laser source in welding low thickness C70 (AISI1070) plain carbon steel. The process is studied by evaluating the influence of the main parameters on its feasibility. The activity pointed out that, by properly selecting the main parameters, it is possible to achieve sound and crack-free weld beads with a maximum penetration as high as 200 μm and a very small heat affected zone. The main interesting point concerning this specific welding process is related to the fact that, by simply selecting the proper process parameters, it is possible to achieve high productivity working cycles involving laser cutting, welding and marking on the same machine and exploiting the same workpiece positioning
Numerical and Experimental Study of High‐Speed Laser Cutting of Copper Current Collectors: Process Optimization for Quality Assessment
Full text linkEnsuring high-edge quality in battery current collectors is crucial for improving battery performance and preventing potential safety issues. Defects such as uneven cuts, spatter, and excessive remelted zones can negatively impact the current collectors' electrical conductivity and mechanical integrity. Laser cutting offers advantages over mechanical methods by enabling faster processing, higher precision, and greater energy concentration. This study models and predicts defect occurrence under varying process parameters, focusing on the interaction between a single-mode continuous-wave (CW) laser and a copper current collector foil. Key factors influencing edge profile defects and cutting quality are investigated through experimental analysis and numerical simulation. A Computational Fluid Dynamics (CFD) model based on the volume of fluid method identifies parameters affecting the physical phenomena and optimal cutting conditions. Model validation is achieved by comparing experimental results across a range of process parameters associated with distinct defect formation modes. This model enables the prediction of defect types across a wide spectrum of laser speeds (2–25 m s−1), power levels (200–1000 W), and foil thicknesses (8–16 (Formula presented.)). Findings serve as a guideline for selecting process parameters when using current collectors of varying materials and thicknesses. © 2025 The Author(s). Advanced Materials Technologies published by Wiley-VCH GmbH
Micro-machinability of A-286 Steel with and without Laser Assist
No full textAbstractMachinability of high nickel content steels (e.g. stainless) is known to be challenging. This paper presents an experimental study of the micro-machinability of A-286 (∼43 HRC), a precipitation-hardened high nickel content steel. Micro milling experiments are carried out under dry, wet, and laser-assisted conditions, and the resulting surface morphology, burr, part feature depth, tool wear, and cutting forces are analyzed. It is found that laser-assist consistently yields the best results characterized by minimal chip adhesion to the workpiece surface, low cutting forces, good feature depth accuracy, low tool wear, and acceptable burrs
5 Axes computer aided laser milling
No full textIn this paper a 5 axes CAM procedure for the laser milling of free form surfaces has been developed and experimentally verified. The laser beam is deflected by a galvanometric scanning head and is directly moved on the working surface by the CNC controlled axes of a machine center. The procedure has been implemented in a software called CALM (computer aided laser manufacturing) able to generate the laser paths and the movements of the controlled axes reducing the defects on the workpiece. The approach is based on the sequential overlapping of the scanning passes on the working area. The different working areas in every laser displacement are obtained directly from the triangulation of the whole surface to machine
Long Pulse Laser Wire Deposition of Hard Steels
No full textAbstractLaser deposition of hard steel wires on martensitic stainless steel substrates has been investigated in order to evaluate the possibility of performing localized mold repairs. An experimental campaign has been carried out to assess the role of the deposition strategy and process parameters such as pulse duration, peak power and frequency on process outcome. The extent of the dilution layer between the substrate and deposited track, as well as tempering effects due to the mutual interaction between tracks and layers, are studied as functions of process parameters in order to assess the characteristics of the deposited tracks. In particular, it is observed that under suitable conditions hard (HV>550) deposits can be achieved with minimal tempering effects even in the case of multiple tracks and layers
Experimental investigation on the effect of spot diameter on continuous-wave laser welding of copper and aluminum thin sheets for battery manufacturing
Full text linkWelding of dissimilar materials, particularly copper and aluminum alloys, has gained considerable industrial interest in many different electric and electronic fields, such as the production of lithium-ion batteries for automotive applications. The differences in physical and chemical properties of these materials make fusion welding processes difficult to apply due to the formation of hard and brittle intermetallic compounds that impair both mechanical and electrical performance. In this paper, the effect of spot diameter on dissimilar laser autogenous lap-welding of copper and aluminum was studied. Experiments were conducted using a mid-power fiber laser source equipped with a galvo scanner and two different focal lengths to obtain two different spot diameters. The results showed that a smaller spot diameter promoted the formation of sound weld beads with better control of penetration depth, reduced mixing of the base metals and lower laser power requirements. By selecting the correct process parameters, good mechanical properties and low contact resistance could be obtained with both focal lengths. SEM-EDX analysis confirmed that a smaller spot diameter minimized the formation of copper rich phases in the weld bead
The effect of process parameters on the high-speed cut quality of Li-ion electrodes using a single mode continuous fiber laser
Full text linkCoated Al and Cu current collectors are employed in the production of Li-ion batteries (LIBs) serving as cathodes and anodes, respectively. The increasing demand and the need for net zero-defect cutting quality are driving industrial production towards fast and reliable technologies. Laser cutting of LIB electrodes is an efficient and cost-effective alternative to conventional mechanical methods, enabling high accuracy and less damaged active material while maintaining high processing speeds. Thanks to remote laser technology flexibility, several combinations of process parameters, electrode material, and thicknesses of the electrode sandwich have been studied. This material variety discussed in the literature reflects the need of the industry to exploit different solutions. Currently, electrode cutting mainly involves the application of short pulse nanosecond (ns) fiber laser. However, the fast-advancing technology of laser manufacturing (including laser sources, optics and scanning heads) allows for new opportunities to improve process productivity and quality. This study evaluates the interaction between a single mode (SM) continuous wave (CW) source and LIB electrodes, exploring the effects of laser power and scanning speed (up to 11 m/s) on thermal defects. These include clearance width and heat affected zone (HAZ) for the anode, as well as HAZ width and the quantity of spherical defects detached from the aluminum foil for the cathode. This investigation identified a significant reduction of defects for both materials when higher speeds are set. Specifically, high-quality cuts were achieved at 5.5 m/s for the anode and 4.4 m/s for the cathode, with a clearance width kept below 20 μm and HAZ under 30 μm
High speed laser cutting of ultrathin metal foils for battery cell production
No full textLaser-based manufacturing has become a key enabling technology in the production of batteries and battery cells for the e-mobility field. Several applications, in fact, have already been industrialized, such as laser-based welding, cutting, stripping, and cleaning. Among all those technologies, laser cutting, in particular, has to deal with several very stringent constraints: the presence of highly reflective materials (aluminum and copper), very low thicknesses (6-12 mu m), on-the-fly processing, and high quality of the cutting surface. According to those considerations, the present paper deals with the application of remote cutting of 12 mu m thick aluminum and 6 mu m thick copper foils by means of a galvo scanner and two different fiber laser sources: single mode constant wave and nanosecond pulsed wave ones. The experimental activity is devoted to understanding the feasibility of the process and to point out the pros and cons of the two different lasers involved. The cutting edges are analyzed by means of optical and SEM microscopy, in order to characterize cutting quality. The process is also characterized in terms of maximum achievable speed in order to understand the limits of both lasers and galvo scanning systems
Aging Behaviour of a 12.2Cr-10Ni-1Mo-1Ti-0.6Al Precipitation-Hardening Stainless Steel Manufactured via Laser Powder Bed Fusion
Full text linkThe combination of precipitation-hardening stainless steels (PH-SS) and laser powder bed fusion (LPBF) enables the manufacturing of tools for plastic injection moulding with optimised geometry and conformal cooling channels, with potential benefits in terms of productivity, part quality, and tool duration. Moreover, the suitability of LPBF-manufactured PH-SS in the as-built (AB) condition to be age-hardened through a direct aging (DA) treatment enables a great heat treatment simplification with respect to the traditional solution annealing and aging treatment (SA). However, plastic injection moulding tools experience severe thermal cycles during their service, which can lead to over-aging of PH-SS and thus shorten tool life. Therefore, proper thermal stability is required to ensure adequate tool life and reliability. The aim of the present work is to investigate the aging and over-aging behaviour of a commercially available PH-SS (AMPO M789) manufactured by LPBF in the AB condition and after a solution-annealing treatment in order to evaluate the effect of the heat treatment condition on the microstructure and the aging and over-aging response, aiming at assessing its feasibility for plastic injection moulding applications. The AB microstructure features melt pool borders, oriented martensite grains, and a cellular solidification sub-structure, and was retained during aging and over-aging. On the other hand, a homogeneous and isotropic martensite structure was present after solution annealing and quenching, with no melt pool borders, cellular structure, or oriented grains. The results indicate no significant difference between AB and solution-annealed and quenched specimens in terms of aging and over-aging behaviour and peak hardness (in the range 580–600 HV), despite the considerably different microstructures. Over-aging was attributed to both the coarsening of strengthening precipitates and martensite-to-austenite reversion (up to ~11 vol.%) upon prolonged exposure to high temperature. Based on the results, guidelines to aid the selection of the most suitable heat treatment procedure are proposed
Experimental Investigation on the Effect of Nickel-plating Thickness on Continuous-wave Laser Welding of Copper and Steel Tab Joints for Battery Manufacturing
Full text linkThe welding of dissimilar materials, such as copper and steel, holds significant industrial significance in the production of electric vehicle batteries. These materials are commonly used in the case of connections between busbars and cylindrical cells inside a battery pack. To optimize welding and guarantee protection against corrosion, nickel is commonly used in the form of a coating. In this paper, the effect of nickel plating thickness on copper-to-steel welds made with laser technology is investigated. The initial phase consists of a statistical characterization of the nickel plating thickness of the busbar in order to identify the thickness ranges. Experiments were conducted using two different fiber laser sources (a single-mode laser source and a beam-shaping laser source) equipped with a Galvo scanner head; the fluence value and the thickness of nickel plating varied during the experiments. The study conducted has revealed that the thickness of nickel plating plays a crucial role in the weld bead interface, particularly when using a single-mode source. Furthermore, when using the beam-shaping laser source, the fluence employed can have a significant impact on both the depth of penetration and the interface width
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