Fig 4 - uploaded by Mohammad Khairul Azhar Abdul Razab
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Schematic illustration of the laser ablation. The laser beam interacts with the coating layers, which induces the surface plasma and shockwave (Prinsloo et al., 2007).
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Laser cleaning has been identified as an ideal technology to replace conventional chemical techniques in the
motorcar coating removal process to maintain the sustainability of our environment. This is due to the unique
characteristics of this cleaning technique, such as being versatile, precise, controllable, lack of waste generation,
and environme...
Context in source publication
Context 1
... coated layer into highly compressed plasma. This will generate a shock wave that ejects the layer into fine particles. The substrate behind the layer is preserved by keeping the laser energy density below the damage threshold. Although the exact mechanism of the laser coating removal is not fully known, it can be easily demonstrate, as seen in Fig. 4. In this process, the coating is ablated and the effluent is ejected from the metal substrate at a high velocity. This condition will produce pyrolysis gases and inorganic materials as the by-product (Mongelli, 2005). The more detailed mechanism of the ablation process is shown in Fig. ...
Citations
... However, three surface pre-treatment methods which include surface grinding at 80 grit, sandblasting and chemical cleaning resulted in welds with deepest FZ and tensile properties of the welds are similar compared to the unwelded control specimens. In recent times, the laser cleaning method, otherwise referred to as green cleaning technology, has distinct capabilities to enhance the coupling efficiency of titanium surface and improve weld penetration without causing any environmental pollution, damaging the base metal or creating health hazards to the workers, has emerged a better replacement for the conventional pollutant cleaning technologies , Razab et al., 2018, Kumar et al., 2010, Xiong et al., 2018. Kumar et al. (2010) stated that high-quality, defect-free weld was achieved during pulse welding of laser-cleaned Ti-3Al-2.5V ...
... Laser cleaning is a new technology with the advantages of requiring no contact, being environmentally friendly, and being able to be automated or controlled remotely. Hence, it has attracted attention from scholars and the industry [6][7][8][9][10][11]. With the development of laser cleaning technology, the cost of laser cleaning machines has significantly decreased. ...
Steel cables used to raise sluices require a layer of corrosion-resistant grease, which must be periodically replaced. It is time-consuming and laborious, and conventional manual cleaning, mechanical cleaning, and chemical cleaning methods have many drawbacks. In this paper, a nanosecond pulsed fiber laser is used to clean hardened surface grease from such cables. An experimental system was designed to study the effects of parameters such as the laser power, scanning speed, cleaning frequency, and defocusing amount. Macroscopic and microstructural observations were conducted on the surfaces of steel cables before and after cleaning using cameras, optical microscopy, scanning electron microscopy, and energy dispersive spectrometry. With the optimal parameters, laser cleaning can effectively remove hardened grease from steel cable surfaces without damaging the galvanized layer and the steel wire matrix. Ablation, gasification, and evaporation are the main mechanisms by which grease and dirt are removed. This study lays a foundation for optimizing the laser cleaning of steel sluice cables at work sites.
... Cleaning contaminated surfaces with laser ablation has several advantages, such as no contact, ease of control, and high precision (Leone et al., 2015;Delaporte et al., 2003;Marimuthu et al., 2019). Furthermore, laser cleaning is an eco-friendly process that does not require the use of acid solutions or abrasive materials, thereby minimizing the generation of secondary waste (Razab et al., 2018). This contributes to the circular economy by reducing the amount of waste generated and helps achieve the SDGs by reducing the amount of hazardous waste generated. ...
... 11,48 Laser cleaning is widely used for cleaning metal surfaces and art restoration by means of removing surface rust or oxides layers. [49][50][51] Laser surface texturing is used for preparing surfaces to assist next steps in manufacturing process. 52,53 This may include laser ablation treatment for modifying surface characteristics, particularly tribological and wettability, to improve the properties of material parts. ...
Laser ablation dynamics encompasses studies of fundamental physical processes of mid infrared laser ablation. Understanding the mechanisms of IR laser desorption and ionization can lead to improvements in laser ablation-based techniques and expansion of their applications. Control of material removal ensures both accuracy and precision of the laser ablation-based techniques. The laser ablation mechanism in the studied wavelength region, is a process of water vaporization and photothermal disruption of tissue. Glycerol was used as the ablation target to establish the methods. Experiments were first aimed at developing methods to monitor material removal during ablation using a 2.94 µm wavelength mid-IR laser at laser fluences between 5 and 50 kJ/m2. This was achieved by using continuous visible laser light scattering in the expanding plume at atmospheric pressure and laser induced acoustic waves. Instantaneous plume velocities for glycerol and rat liver tissue were determined at distances 0.5 – 2.0 mm from the sample surface. The fraction of the laser energy transferred to the expanding shock wave was determined using the Taylor shock wave model. Efficient energy conversion at higher laser fluences is consistent with a phase explosion mechanism. A piezoelectric based method for measuring absorbed laser energy was demonstrated for ablation of glycerol and rat liver tissue. The higher fluence required for tissue compared to glycerol is likely due to its greater tensile strength which necessitates a greater volumetric energy density for particle formation and ejection. Automation of the laser ablation and monitoring system was achieved using a LabVIEW software algorithm. A system was developed for the real-time data acquisition, measure the laser energy absorbed by the sample and adjusting the laser pulse energy to control the material removal.
... The LACR process has already been established for use in industries such as marine, 2-4 aerospace, [5][6][7] military, 8,9 nuclear, [10][11][12] and automotive companies, 13 with great benefit to efficiency and waste maintenance, ultimately providing cost savings. The technology has also been extended within the art world 14,15 as well as for cultural heritage and preservation. ...
The application of protective organic coatings is one of the most effective and commonly used corrosion mitigation strategies. To maintain the protective nature of coatings on long-term-exposed surfaces such as steel bridge components, coatings must be periodically removed and reapplied. A relatively new method called laser ablation coating removal (LACR), which incorporates a high energy nanosecond pulsed laser beam in combination with a high efficiency filtration system, allows for safe and effective removal of coatings and contamination from metal surfaces. In this study, LACR cleaning is tested on legacy bridge steel components to investigate the effect on substrate cleanliness and steel mechanical properties. These bridge sections were never blasted and contain a 20–100 μm thick mill-scale layer (iron oxide) below several coating layers (including lead-rich coatings). The top micron of the oxide layer is melted by LACR and also thermally insulates the underlying steel and prevents any melting within the metallic substrate. The resulting surfaces are analyzed using microscopy, hardness testing, tensile, and fatigue testing, and it is shown that LACR does not cause any measurable detrimental effects to the bulk mechanical properties of the bridge steel, as well as effectively removes all paint coatings. Furthermore, adhesion testing on LACR-cleaned substrates shows excellent adhesion, qualifying above adhesion requirements for coated steel.
... While these methods have reached a considerable level of maturity, they also come with significant drawbacks. For instance, chemical and mechanical cleaning methods are labor-intensive, prone to substrate damage, and can generate substantial waste, which leads to environmental pollution [2,3]. In comparison, laser cleaning technology is regarded as a greener and more promising alternative, particularly in the context of the global manufacturing industry's transformation. ...
At present, aircraft radome coating cleaning mainly relies on manual and chemical methods. In view of this situation, this study presents a trajectory planning method based on a three-dimensional (3D) surface point cloud for a laser-enabled coating cleaning robot. An automated trajectory planning scheme is proposed to utilize 3D laser scanning to acquire point cloud data and avoid the dependence on traditional teaching–playback paradigms. A principal component analysis (PCA) algorithm incorporating additional principal direction determination for point cloud alignment is introduced to facilitate subsequent point cloud segmentation. The algorithm can adjust the coordinate system and align with the desired point cloud segmentation direction efficiently and conveniently. After preprocessing and coordinate system adjustment of the point cloud, a projection-based point cloud segmentation technique is proposed, enabling the slicing division of the point cloud model and extraction of cleaning target positions from each slice. Subsequently, the normal vectors of the cleaning positions are estimated, and trajectory points are biased along these vectors to determine the end effector’s orientation. Finally, B-spline curve fitting and layered smooth connection methods are employed to generate the cleaning path. Experimental results demonstrate that the proposed method offers efficient and precise trajectory planning for the aircraft radar radome coating laser cleaning and avoids the need for a prior teaching process so it could enhance the automation level in coating cleaning tasks.
... The commonly used methods of glue removal, such as high pressure water washing [1,2], mechanical brushing, and high temperature combustion, will damage the concrete pavement when the pollution is serious in the process of removing the glue layer. Compared with the traditional methods of chemical cleaning, laser cleaning is novel, with a higher efficiency and better performance [3][4][5][6] cleaning method. It has shown remarkable ability to remove all forms of surface contamination. ...
Based on the principle of laser ablation and elastic vibration effect, a model of continuous nanosecond combined laser removal of rubber marks on a concrete surface was established. The model can explain the evolution of temperature, stress, and removal depth on time and laser energy density during laser cleaning. The results show that the theoretical adsorption force between the rubber layer and the concrete base is approximately ${3.88} \times {{10}^{- 9}}\;{\rm N}$ 3.88 × 10 − 9 N . The continuous laser cleaning threshold is ${561.31}\;{{\rm J/cm}^2}$ 561.31 J / c m 2 . In the combined laser, the continuous laser is ${534.41}\;{{\rm J/cm}^2}$ 534.41 J / c m 2 , and the nanosecond laser is ${0.35}\;{{\rm J/cm}^2}$ 0.35 J / c m 2 . As the delay time between the 2 ns laser beams increases, the maximum peak in the temperature curve gradually decreases. The optimal cleaning delay was obtained as $\Delta {t} = {0.65}\;{\rm S}$ Δ t = 0.65 S . The peak temperature at the characteristic position (0 µm, 0 µm) is 592.13 K, which is lower than the vaporization temperature of the rubber layer. The thermal stress values generated at this characteristic position exceed the adsorption stress values, indicating that the elastic removal mechanism is the main removal mechanism at the junction between the rubber layer and the concrete substrate.
... In this process, pulsed wave (PW) lasers are often preferred from ms to ns duration ranges [15]. The paint removal processes can operate in two main ways: (i) direct material removal from the surface if the laser wavelength is sufficiently well absorbed by the polymeric material, or (ii) indirect material removal where the laser is absorbed by the metal at the polymer/metal interface [16][17][18][19][20], where the heating causes shock waves [21] that may expel the material in particles much larger than the beam size [22]. Today, several laser sources, spanning from IR to UV have become commercially available in robust and reliable packages, working as industrial workhorses. ...
The electric drives used in traction applications employ conventionally pure Cu bars bent to the required form, inserted in the stator and welded by a laser at the extremities. These extremities, which are referred to as Cu hairpins, should be stripped off from the electrically isolating polymeric enamel. Laser stripping is industrially used to remove the enamel from the Cu surface. Pulsed wave lasers are employed for the purpose with a large variety of solutions industrially available to the end users. The peculiar process may give way to material removal by surface heating for instance using infrared radiation (IR) or ultraviolet (UV) lasers or an indirect material expulsion via near-infrared (NIR) sources. Accordingly all major laser sources, namely CO 2 , active fiber, active disk, and Nd:YAG at different wavelengths, may be used for the purpose. Such laser sources possess very different characteristics regarding the pulse durations, power levels, and beam diameters. As newer laser system solutions are made available, the need for methods and experimental procedures to compare the process performance also increases. This work compares 7 different hairpin stripping solutions based on contemporary pulsed laser sources along with a detailed comparative analysis method. Initially, the 7 laser sources are used for hairpin stripping. The process quality is analyzed through surface morphology, chemistry, and the mechanical strength upon laser welding. Productivity and efficiency indicators are collected. Using the collected data, the work proposes system configurations for three different scenarios prioritizing quality, productivity, and cost.
... The application of organic coatings to a well-cleaned surface is critical to avoid coating failure owing to under-film corrosion. The ablative mechanism of lasers has also proven to be an effective method for surface cleaning and has been widely used in various fields [17,18], including the automotive, aerospace, and marine industries [19][20][21][22]. Although PL has been proven to be effective in cleaning rust layers of tens of microns, the thickness of rust layers in civil engineering structures, especially bridge structures, can often reach tens of millimeters, making it difficult for PL to penetrate and completely ablate thick rust layers. ...
This study explored the feasibility of direct coating of steel surfaces treated with a continuous-wave laser (CWL). The adhesion and corrosion resistance of Heavy-Duty Paint coatings were evaluated on CWL-treated surfaces and compared with those of surfaces treated with molten alumina blasting. The results showed that the surface texture created by CWL provided greater adhesion of the Rc-I coating than its cohesive strength. However, the presence of oxides on the CWL-treated surfaces caused a high cathodic disbondment (CD), which reduced the corrosion resistance of the coated steel in corrosive environments. Decreasing the laser head sweep speed can improve the surface roughness and area but does not address the issues of CD and corrosion creep (CC). This study concludes that, given the limitations of current commercial CWL systems, it is recommended to blast CWL-treated surfaces before coating to improve durability and corrosion resistance in corrosive environments.
... Laser cleaning technology has developed rapidly in recent years [1][2][3][4][5][6][7]. Compared with chemical, mechanical grinding and ultrasonic cleaning methods, laser cleaning technology is an environmentally friendly method, which is characterized by high efficiency, good stability and little damage to the substrate [2]. ...
... For the fiber laser treatment, there existed several metal crystalline cellular structures and deep concave pits as shown in Figure 8, which indicated the substrate damage emerging. The substrate damage in the coating removal process was mainly due to thermal effect-induced strain and stress [3,30]. The fiber laser with good beam quality was expected to possess a Gaussian spatial profile, which exhibited peak intensity at the center of the beam and an exponential decay towards the edge. ...
In this study, a fiber coupled high power side-pumped Nd:YAG laser system for laser cleaning is presented. Based on the two-rod structure and two stages amplifiers, the maximum average output power of 783 W with corresponding pulse energy of 52 mJ at 15 kHz has been achieved. The fiber coupling efficiencies after the master oscillator, one stage amplifier and two stages amplifiers reach to 99%, 98.3% and 94%, respectively. A laser cleaning machine prototype composed of the master oscillator and one stage amplifier with an average output power of greater than 500 W has been developed and achieved better nondestructive cleaning effect for thermal control coating removal compared with commercial fiber laser cleaning machines. This study provides a new method for developing high power laser sources for nondestructive laser cleaning equipment.
