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SEM micrographs taken from the cross-section of laser-cut samples: (a) and (b) are from specimen laser-cut at speed of 3.5 m/min; (c) and (d) are from specimen laser-cut at speed of 3 m/min.
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This study aimed to characterize the surface quality of beech wood (Fagus sylvatica L.) cut by a CO2-laser. Boards were conditioned to a low (about 8% moisture content), 12%, and a high, (about 18%) moisture content. Laser cutting was performed at varying processing parameters, i.e. cutting speed, gas pressure and focal-point position. A confocal m...
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... discover the changes that likely occurred in the anatomical structure of the specimen during the laser cutting, a scanning electron microscope (SEM) was used. SEM micrographs of the specimen conditioned to 8% MC and laser-cut at different cutting speeds (3.5 m/min -and 3 m/min), with the focal point focused on the top surface, are shown in Figure 6. Figures 6(a) (magnification: 2625x) and 6b (magnification:10662x) show different magnified micrographs taken from the specimen cut at a speed of 3.5 m/min, while Figures 6(c) (magnification: 3075x) and 6d (magnification:11748x) show micrographs of a specimen cut at speed of 3 m/min. ...
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... 6(a) (magnification: 2625x) and 6b (magnification:10662x) show different magnified micrographs taken from the specimen cut at a speed of 3.5 m/min, while Figures 6(c) (magnification: 3075x) and 6d (magnification:11748x) show micrographs of a specimen cut at speed of 3 m/min. It is evident from the micrographs that the anatomical integrity of the specimen cut at 3 m/min in most of the areas (Figure 6(a,b)) is lower than that obtained at 3.5 m/min ( Figure 6(c,d)). The middle lamella between the fiber walls was completely degraded when the specimen was cut at a low speed (Figure 6(c)), while at a high speed the degradation of middle lamella was only partial. ...
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... 6(a) (magnification: 2625x) and 6b (magnification:10662x) show different magnified micrographs taken from the specimen cut at a speed of 3.5 m/min, while Figures 6(c) (magnification: 3075x) and 6d (magnification:11748x) show micrographs of a specimen cut at speed of 3 m/min. It is evident from the micrographs that the anatomical integrity of the specimen cut at 3 m/min in most of the areas (Figure 6(a,b)) is lower than that obtained at 3.5 m/min ( Figure 6(c,d)). The middle lamella between the fiber walls was completely degraded when the specimen was cut at a low speed (Figure 6(c)), while at a high speed the degradation of middle lamella was only partial. ...
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... is evident from the micrographs that the anatomical integrity of the specimen cut at 3 m/min in most of the areas (Figure 6(a,b)) is lower than that obtained at 3.5 m/min ( Figure 6(c,d)). The middle lamella between the fiber walls was completely degraded when the specimen was cut at a low speed (Figure 6(c)), while at a high speed the degradation of middle lamella was only partial. The middle lamella is in general mostly composed of lignin, pectic polysaccharides and a small amount of proteins ( Lazić et al. 2018), and the lignin proportion can be up to 84%. ...
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... vibrational changes in the molecules caused by the CO 2 -laser result in thermal action ( Haller et al. 2001, Kačík andKubovský 2011). What can be clearly seen in Figure 6(b) is apparently a portion of polymer chains, maybe the crystalline portion of cellulose, in the deeper walls of fiber, S 2 and S 3 , remained unchanged by thermal degradation and looks like a white portion protruding out from the end of fibers in the samples cut at higher speed. In contrast, at a lower speed, as shown in Figure 6(d), the polymer chains were completely degraded without any polymer chains remaining. ...
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... can be clearly seen in Figure 6(b) is apparently a portion of polymer chains, maybe the crystalline portion of cellulose, in the deeper walls of fiber, S 2 and S 3 , remained unchanged by thermal degradation and looks like a white portion protruding out from the end of fibers in the samples cut at higher speed. In contrast, at a lower speed, as shown in Figure 6(d), the polymer chains were completely degraded without any polymer chains remaining. This may be explained by the fact that at lower speed the exposure time of the wood to the laser is higher and the heat energy generation surpasses the energy dissipation through conduction. ...
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... residual energy is still sufficient enough to degrade the lignin and cellulose polymers at the point of exposure; however, the energy conducted through the probably cellulose gets dissipated to the underlying lignin and seems sufficient enough to degrade the underlying lignin up to a certain distance (∼ 1 µm) from the exposure point, leaving the crystalline portion of cellulose unaffected. As a result, the unaffected cellulose protrudes from the cut end of the fibers, as can be seen in Figure 6(b). These projections are more towards the cell lumen, as the cellulose content is higher towards that side. ...
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The moisture content of wood influences its machinability and the resulting quality of the machined surface. This study aims to explore the impact of varied moisture content on the final quality of beech wood cut by a CO2 laser (Fagus sylvatica L.). Laser cutting was performed on beech lumbers conditioned at moisture levels of 0%, 8%, 12%, and 18%....
Citations
... The aforementioned changes in technology are linked with speci c advantages such as a reduction in pneumatic dust collection, which is recognized for its high economic impact, accounting for 30% of total production costs [3]. In general, the processing of wood with laser technology affects its chemical composition and the microstructure of cell walls, thereby affecting its colour, morphology, and hydrophilic/hydrophobic characteristics [4]. In contrary, traditional processing leads to modi cations only in the physical properties of the processed surface [3,4]. ...
... In general, the processing of wood with laser technology affects its chemical composition and the microstructure of cell walls, thereby affecting its colour, morphology, and hydrophilic/hydrophobic characteristics [4]. In contrary, traditional processing leads to modi cations only in the physical properties of the processed surface [3,4]. ...
... Surface roughness Figure 6 illustrates the impact of moisture contents (0%, 8%, 12%, and 18%) on the average surface roughness (R a ). The R a values for specimens conditioned at 0%, 8%, 12%, and 18% were 5.6 µm, 5.5 µm, [4]. The mentioned authors reported R a values of laser-cut specimens conditioned at 8%, 12%, and 18% as 11.1 µm, 13.4 µm, and 13.3 µm, respectively. ...
The moisture content of wood influences its machinability and the resulting quality of the machined surface. This study aims to explore the impact of varied moisture content on the final quality of beech wood cut by a CO2 laser (Fagus sylvatica L.). Laser cutting was performed on beech lumbers conditioned at moisture levels of 0%, 8%, 12%, and 18%. The Laser-cut specimens were evaluated for surface roughness and waviness by using a stylus surface profilometer at three measuring locations: top, middle, and bottom. The total color difference ΔE was also assessed using a spectrophotometer at the same three locations. The most intriguing findings revealed that surface specimens with higher moisture content are lighter than those with lower moisture content. Specifically, the top areas of specimens with different moisture content exhibited lighter shades than those in the middle and bottom areas. Notably, the surface profile of the specimens remained unaffected by variations in moisture content levels.
... Factors such as moisture content, grain direction, and wood species can greatly influence the cutting process, resulting in varying outcomes in terms of cut quality, efficiency, and material behavior. As the demand for refined wood products grows, understanding these interactions is paramount to optimizing laser cutting parameters and ensuring product quality [16][17][18][19]. ...
... Various studies focused on the impact of CO 2 laser processing parameters on the surface roughness. Rezaei et al. [16] investigated the impact of parameters such as cutting speed, focal-point positions, and gas pressure on the surface roughness of laser beech wood. Results show that the cutting speed and focal-point position has little to no effect on surface roughness while the increase in gas pressure lowered the average surface roughness. ...
... The very evaluation of these irregularities becomes questionable from the point of view of the combined effects of anatomy and cutting. In a radial or tangential cut, unevenness is evaluated through the roughness profile [16,[25][26][27][28]. However, in the case of a cross-section, it becomes insufficient, since through the most used filter value λc = 2.5 mm, there is a significant attenuation of the amplitude for a wavelength of irregularities greater than 2.5 mm. ...
The present paper deals with the analysis of cross-section surface irregularities after CO2 laser cutting. The surface irregularities of beech (Fagus sylvatica L.), oak (Quercus petraea), and spruce (Picea abies L.) wood were quantified by primary profile parameters using a digital microscope. The arithmetic mean height (Pa), used as the basic parameter, was supplemented by amplitude parameters (Pv, Pp, Pz) and the Psm parameter, through which the shape of the irregularity was specified in more detail. A statistically significant change was demonstrated when changing the values of the feed speed and the power of the CO2 laser. The results of this article confirm that the surface irregularities increased with an increasing laser power and decreasing feed rate. The scanned topographic images also provide a more detailed explanation of the measured P-parameters and point out the risks associated with the evaluation of the cross-section with the primary profile.
... (Ramage et al. 2017). Considering modern manufacturing processes, lasers have been used before to cut, mark, and surface process wood products by means of a controlled combustion reaction mechanism, such as those at the kerf zone (Barcikowski et al. 2006;Letellier and Ramos-Grez 2008; Rezaei et al. 2022). Nonetheless, research considering the deformation of wood material by lasers has apparently not been pursued yet to the best knowledge of the authors. ...
... The hemicelluloses are smaller, branched molecules that link the lignin and cellulose together in each layer of the cell wall (Ross et al. 2010). All the latter distributed along the longitudinal growth axis and arranged radially (Rezaei et al. 2022). Moreover, cellulose consists of a crystalline polymer with amorphous regions (Rowell 2012); it is a biopolymer made out of β-glucose molecules, which makes up approximately 50% of the weight of wood. ...
Wood is a noble, versatile, and renewable material which plays an important role in sustainable manufacturing. The present study shows that it is feasible to laser bend veneers of different wood species by applying infrared energy in the form of a scanned laser beam. Bending height, i.e., deflection of the veneer measured as the vertical elevation of its edge points from the horizontal plane; were achieved on three wood types, namely: beech, yesquero, and ulmo. Process parameters and wood properties considered relevant to the response variable are laser energy, moisture content, water loss, density, and wood species. Experimental results indicate that specimens 15 cm long, 3.5 cm wide and 1.5 mm thick achieved bending heights ranging from 0.35 cm (beech) up to 4.8 cm (yesquero). Largest average height of 4.45 cm was achieved in beech veneers at equilibrium moisture content of 13% under maximum laser energy of 1061 J. On the other hand, ulmo specimens having 0% moisture content, after oven drying for 72 hour at 40ºC, also showed considerable average deflection height of up to 3.1 cm. This reaffirms that free water loss is not the only mechanism for fibre contraction, but that cell wall bound water loss during the laser wood interaction also causes considerable shrinkage, as expected. Machine-Learning analysis of the experimental data suggests the algorithm that better suited the response variable was the Gaussian Process regression since it showed the highest correlation coefficient and the lower RMSE. Confirming that moisture content explains almost 45% of the model's predictability, followed by laser energy with 35%, while water loss (both free and bound) was ranked third.
... A slow cutting speed and high laser power, will melt, carbonize and evaporate more material due to an increase in the local heat. Similar results were reported by [20] when cutting Norway spruce and by [17] when cutting beech, along the grain in a tangential plane, with a CO 2 laser. ...
... Rezaei et al. [17] compared CO 2 laser cut surfaces along the grain of beech with those processed by sawing and concluded that the Ra parameter was rougher in the case of the laser. The variation of Ra with the laser cutting speed (3 or 3.5 m/min) and location of the focal point (on the surface or in the middle of the specimen thickness) was not significant. ...
The evaluation of surface quality is an important criterion to understand the effect of the cutting angle in relation to the grain and of the processing tool on wood. This paper examines, in a comparison, the surface quality of maple cut through by CNC and CO2 laser, for different angles with regard to the wood grain: 0°, 15°, 30°, 45°, 60°, 75°, and 90° and at different feed speeds of the CNC router: 2; 2.5; 3; 3.5 and 4 m/min. The direction of processing as related to the grain was a more significant factor in comparison with the feed speed when CNC was used, with best options for 0°, 90° and 75° and worst for 15°, where fuzzy grain was predominant, followed in order by 30°, 45°, and 60°, where pull-out material prevailed. The laser smoothed the core roughness, Rk, with no significant differences as related to the wood grain direction and enhanced an anatomical waviness earlywood-latewood, with the earlywood processed deeper. As the cutting advanced from along to across the grain, the laser uncovered more wood anatomical details and with less destruction. No significant differences in Rk between CNC cutting and laser processing were found for angles: 0°, 60°, and 75°, but surfaces processed at 15°, 30°, and 45° were significantly rougher in the case of CNC cutting. Comparative FTIR investigation of surfaces cut by laser and CNC (at 0° and 90°) clearly revealed temperature-induced chemical changes, such as hemicelluloses degradation, possibly demethylation and advanced condensation in the structure of lignin, in the case of laser processing.
The paper describes a study on the effects of beam power and feed rate in the process of cutting fresh wood with a CO2 laser on water contact angle on the cut surface. The study involved several broadleaved tree species (oak, birch, alder, plum, and apple tree) and one coniferous species (pine). Samples were cut with a Trumpf TLC1005 laser equipped with a TruFlow 6000 CO2 resonator at a wavelength of 10.6 μm at three power output settings (1 kW, 2 kW, and 3 kW) and one feed rate (0.4 m∙min− 1). Contact angle was measured by pipetting a drop of distilled water on the wood surface and recording the process with a camera. Subsequently, images of the drop were analyzed over one minute at 10 s intervals to determine changes in contact angle for each of the cases examined. It was not possible to measure the contact angle on saw-cut samples as the water was immediately absorbed, while water drops placed on laser-cut samples remained on the surface for over 60 s, with the contact angle decreasing over time for the examined species from an average of 90° to 40°. The higher beam power settings (2 or 3 kW) were found to be preferable for the hardwood species (oak, birch, alder, and apple tree). In turn, in the case of the softwood species (pine), the laser power output did not matter, as both at the low (1 kW) and high (3 kW) settings the drop did not spread over the surface quickly. Finally, the optimum beam power for plum tree wood was found to be 1 kW.
Recently, efforts have been made to develop decoration techniques with CNC router machining and contact production machines in the furniture industry. However, this method is insufficient in micro-processes that require precision. In this research, the innovation of traditional furniture surface treatment techniques as a regression modeling production method with laser technology was examined. For this purpose, beech wood was processed in a CNC laser processing machine with a 130-watt carbon dioxide gas tube, and sample product design and manufacture were made. It has been determined that many furniture surface treatment techniques can be applied with the regression modeling method of CAD/CAM supported laser technology.
