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Laser‐powder bed fusion (L‐PBF) is extensively adopted in the aerospace and automobile industries for producing metallic components. The L‐PBF process involves rapid melting and solidification of metallic powders using a laser source to produce dense parts. Most industrial L‐PBF systems use a fiber‐based laser source that emits a Gaussian beam distribution. However, the conventional Gaussian beam used in L‐PBF processes presents inherent limitations that can impact the quality and properties of the final products. This review aims to provide a theoretical background of laser beam shaping techniques and explores the application of alternative beam shapes in L‐PBF. It investigates how different beam profiles affect the melt pool geometry, process stability, productivity, mechanical properties, microstructure, and surface roughness of fabricated parts. Additionally, it discusses different types of beam shaping techniques and elements utilized to generate distinct beam shapes. Furthermore, different constraints and limitations that hinder the full exploitation of beam shaping are critically discussed. By analyzing the impact of beam shaping in L‐PBF, this review provides insight into optimizing the additive manufacturing process, enhancing part quality, and improving processing performance. It will also help readers to overview the research gaps, challenges, and promising future directions in laser beam shaping applications in L‐PBF. [ABSTRACT FROM AUTHOR]

Machining composite to achieve the desired surface and sub-surface condition, whether through conventional or non-conventional techniques, presents persistent challenges due to their anisotropic thermal characteristics. These challenges escalate when dealing with ceramic matrix composites (CMC) due to their high melting and boiling temperature. This study investigates the surface and sub-surface characteristics of SiC-Al 2 O 3 CMC laser-cut components, produced using a 2 kW quasi-continuous wave laser. The influence of laser parameters such as focal position, cutting speed, number of cutting passes, average power, and assist gas type on surface and sub-surface characteristics have been investigated in detail. The laser cut samples were analysed using white light interferometer, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and 3D X-ray Computer Tomography (XCT) for both surface and sub-surface characteristics. The effect of laser process parameters on the surface composition, surface topology, and sub-surface thermal defects have been studied in detail. The results revealed that multi-pass cutting (16 pass) can be used to achieve lower thermal affected zone (~200 µm) and reduced surface roughness with an overall cutting speed of 625 mm/min. No delamination was observed with multi-pass cutting. Nitrogen was found to be the most suitable assist gas, as it prevented oxide layer formation across the laser cut SiC-Al 2 O 3 CMC surface. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond (PCD) is an important material in the tool industry due to its superior wear resistance and strength. Picosecond laser machining enables accurate cutting, geometric profiling, and precise dimensional features to be produced on PCD. The industrialisation of this manufacturing process necessitates the development of laser systems and process strategies that facilitate high throughput and quality. This paper investigates the feasibility of using a 300 W picosecond laser to machine PCD. It examines the influence of fluence, average power, pulse duration and number of passes on the material removal rate and surface quality. The surface integrity after machining is ascertained using a surface profilometer, optical microscopy and Raman spectroscopy. The results have shown that a high material removal rate of 33 mm3/min (0.11 mm3/min W) at a surface roughness of 2.3 μm is achievable using a fluence of 0.9 J/cm2 at 41.3 MHz and 300 W average power. Raman's analysis of the machined sample suggests a laser-induced graphitisation which is prevalent at high pulse overlap, peak power, and the number of passes. Overall, the study strengthens the idea that with optimised process parameters, a balance is established between productivity and high surface integrity. [ABSTRACT FROM AUTHOR]

The field of protective coatings for industrial applications is continuously evolving, driven by a need for materials that offer exceptional hardness, enhanced wear resistance, and low friction coefficients. Conventional methods of coating development, such as physical vapour deposition (PVD) and chemical vapour deposition (CVD), often face challenges like the necessity of vacuum conditions, slow growth rates, and weak substrate adhesion, leading to inadequate interface bonding. This study introduces a novel approach utilising an integrated laser/sol–gel method for synthesising aluminium nitride (AlN) coatings on EN43 mild steel substrates which overcomes these limitations. The technique employs a high-intensity diode laser with optimal power and translation speeds to consolidate a pre-applied thin layer of sol–gel slurry consisting of aluminium hydroxide, graphite, and urea on the substrate. Chemical thermodynamic calculations were used to predict the slurry composition, along with identifying the critical temperature range and the essential enthalpy needed for the synthesis of aluminium nitride. A three-dimensional heat transfer model was developed to predict the important process parameters, such as scanning speed and laser power density, required to achieve the temperature ranges necessary for a successful deposition process. Optical and scanning electron microscopy techniques were used to examine the surface morphology and microstructure of the coating. Elemental energy-dispersive X-ray spectroscopy and an X-ray diffraction analysis confirmed the synthesis of an aluminium nitride coating with a thickness ranging from 4 to 5 µm. Furthermore, the detection of sub-micron crystalline aluminium nitride structures yielding a metal matrix composite interlayer was indicative of strong metallurgical bonding. Microhardness testing indicated a hardness value of approximately 876 HV. The coated samples with the highest quality exhibited a surface roughness, Ra, ranging from 1.8 to 2.1 µm. Additionally, the coatings demonstrated an exceptionally low coefficient of friction, recorded at less than 0.1. These results represent a significant step forward in this field, offering a cost-effective, efficient, and scalable solution for producing high-quality coatings with superior performance characteristics. [ABSTRACT FROM AUTHOR]

Laser processing is widely used in manufacturing metal alloy aerospace components. Over the last few years there has been an increased interest in exploiting silicon carbide (SiC) based ceramic matrix composite (CMC) materials for aero-engine components, as they possess superior thermomechanical properties compared to conventional alloys. However, laser processing of SiC CMCs is difficult due to their high melting temperatures, and differences present between the thermal and physical properties of the matrix and fibre. This paper investigates the basic characteristics of water jet guided laser (WJGL) cutting SiC/SiC, using a high power 532 nm Q-switched pulsed laser with an average power of 400 W. Experimental trials were performed to understand the effect of different process parameters on the cut quality and overall cutting speed. Cutting speed and pulse frequency were found to be key in determining cut quality and overall cutting speed on the WJGL. Average power also affected overall cutting speed. Due to the cooling nature of the water jet, the thermal damage typically associated with conventional laser processing was eliminated. However, heterogeneous removal of the material matrix and fibres was found to occur where fibres aligned parallel to the direction of the cut length, resulting in non-uniform kerf widths. [ABSTRACT FROM AUTHOR]

This manuscript discusses the experimental results on 300 W picosecond laser machining of aerospace-grade nickel superalloy. The effect of the laser's energetic and beam scanning parameters on the machining performance has been studied in detail. The machining performance has been investigated in terms of surface roughness, sub-surface thermal damage, and material removal rate. At optimal process conditions, a picosecond laser with an average power output of 300 W can be used to achieve a material removal rate (MRR) of ∼140 mm3/min, with thermal damage less than 20 µm. Shorter laser pulse widths increase the material removal rate and reduce the resultant surface roughness. High scanning speeds improve the picosecond laser machining performance. Edge wall taper of ∼10° was observed over all the picosecond laser machined slots. The investigation demonstrates that high-power picosecond lasers can be used for the macro-machining of industrial components at an acceptable speed and quality. [ABSTRACT FROM AUTHOR]

Laser bending is extensively used in many applications including shipbuilding, automotive, microelectronics, and aerospace, due to its advantages of non-contact, flexible manufacturing, and ease of automation. However, the low bending angle observed with conventional temperature gradient bending mechanism restricts its wider application. This investigation aims to develop a new methodology to increase the bending angle of temperature gradient-based laser bending process. In this process, an external cooling source was incorporated at the bottom of the plate (co-axial to the laser source), to increase the temperature gradient between the top and the bottom surfaces. A coupled thermo-mechanical model was developed to simulate the process using COMSOL MULTIPHYSICS® and investigate the effects of external cooling source on bending angle. The study reveals that the bending angle and temperature gradient across the plate thickness can be influenced by the external cooling source. Compared to the conventional technique, the use of external cooling source helps to increase the bending angle by around 20%. Moreover, this method yields a significant reduction of HAZ as a secondary benefit. It is also seen that the amount of residual stress increases with increase in cooling source diameters. [ABSTRACT FROM AUTHOR]