Search Results (9)

Modern manufacturing technologies include wood processing using laser technologies. The most used laser for wood cutting is the CO₂ laser, which offers many advantages such as processing speed, efficiency, and minimal impact on the material’s structure after cutting. To achieve a high-quality cut, characterized by the cutting kerf parameters, it is necessary to know the appropriate combination of cutting parameters, primarily laser power (P) and the cutting speed (v). Therefore, this article investigates the effect of P, v, and cutting direction on the cutting kerf widths on the upper surface WKU, lower surface (WKL), and their ratio (WKR). The analysis was performed on samples of spruce, beech, and oak wood, while also evaluating the influence of the anatomical cutting direction. The correlation coefficient between the predicted values and the measured values is at least 0.94, with the mean square error not exceeding 4%. Consequently, the employed models demonstrate validity in predicting cutting kerf widths and optimizing the cutting process based on the type of timber, cutting direction, and the specified laser parameters. Full article

This paper discusses cutting beech wood (Fagus sylvatica L.) using a CO₂ laser and optimising its feed speed and laser power concerning the roughness of the cut surface and the kerf width. The roughness, defined by the parameters Ra, Rz, Rv, and Rp, and the kerf width changed with varying technological parameters of the CO₂ laser—feed speed and laser power. The lowest roughness was achieved at 50% laser power and a 15 mm·s⁻¹ feed speed, while the highest roughness was reached at 50% and 30 mm·s⁻¹. The lowest kerf width was achieved at 50% laser power and a feed speed of 15 mm·s⁻¹ on both the upper and lower sides and vice versa. The result of the experiment was the creation of second-degree polynomial regression models, from which the optimal values of the technological parameters of the CO₂ laser for cutting wood were determined for surface roughness and kerf width. The achieved accuracy of the models was 98.01% for the kerf width on the upper side, 95.95% for the kerf width on the lower side, 82.71% for the Ra parameter and 85.44% for the Rz parameter. Full article

To reduce defects in wood laser processing, this study establishes a multi-field coupling model that reflects the coupling relationship between laser energy, auxiliary gas, and slit quality. It reveals the temperature field distribution and heat transfer during this process at a macroscopic level. Using the COMSOL Multiphysics 5.6 software to simulate laser processing with or without helium gas assistance, we show that helium-assisted laser processing positively affects the quality of wood processing. We further researched the influence of different laser powers and spot radii on ablation damage volume and gasification volume, and the results indicate that the adopted model effectively simulates the influence of laser power and auxiliary gas on laser cutting ability, accurately reflecting the impact of different process parameters on cutting depth and kerf width. The accuracy and effectiveness of this model were validated through comparison with experimental data. This research enhances process reliability and economic benefits through numerical simulation and prediction, expands theoretical research and engineering applications in the laser processing field, and optimizes and innovates wood processing technology. It provides a promising method for enhancing the added value of wood products and efficiently using wood resources. Full article

Acacia dealbata Link, known as Mimosa in Portugal, is an invasive hardwood species with potential for construction use, but research is limited. The available stock of small-diameter juvenile wood logs can help reduce this gap, but tangential cracking at log ends challenges fastener connections. This study evaluated different treatments to control and reduce end-face cracking in small wood logs during air drying, an economical and environmentally friendly procedure. The extreme two-thirds of sixteen Mimosa logs were subjected to two treatments: one with longitudinal kerfs 15 mm deep along the length (two and three kerfs) and the other with a hollow in the center up to half the length (16 mm and 30 mm diameters). Over 219 days of air drying and compared with the central part, kerfing treatments significantly reduced outer-wood tangential cracking (p < 0.001), with the three kerfs also reducing crack numbers (p < 0.05) but increasing significantly cracks near the pith (p < 0.01). The 30 mm central hollow significantly reduced central perforation cracking (p < 0.05). Prospectively, the results suggest that a combined treatment approach involving cross-cuts could help reduce and/or control end cracking, thereby improving the suitability of wild Mimosa logs for construction use. Full article

In this work, we focus on the prediction of the influence of CO₂ laser parameters on the kerf properties of cut spruce wood. Laser kerf cutting is mainly characterized by the width of kerf and the width of the heat-affected zone, which depend on the laser power, cutting speed, and structure of the cut wood, represented by the number of cut annual rings. According to the measurement results and ANN prediction results, for lower values of the laser power (P) and cutting speed (v), the effect of annual rings (ARs) is non-negligible. The results of the sensitivity analysis show that the effect of v increases at higher energy density (E) values. With P in the range between 100 and 500 W, v values between 3 and 50 mm·s⁻¹, and AR numbers between 3 and 11, the combination of P = 200 W and v = 50 mm·s⁻¹, regardless of the AR value, leads to the best cut quality for spruce wood. In this paper, the main goal is to show how changes in the input parameters affect the characteristics of the cutting kerf and heat-affected zones for all possible input parameter values. Full article

In Ethiopia, sawmills have poor capacity utilization primarily due to the outdated equipment that resulted in a low recovery rate and the production of a high amount of wastage. The lumber recovery rate is the output (lumber) of a log in the sawing process. In Ethiopia, Cupressus lusitanica is significantly used for lumber, for furniture production, construction, poles and posts. Sampled logs were processed according to the normal production rate and standard lumber dimension of the sawmill for the purpose of estimating the lumber recovery rate. The present study aimed to investigate the lumber recovery rate of C. lusitanica and the factors affecting it. A total of 26.93 m³ of lumber was produced by the sawmilling operation, representing 72.86% of the overall lumber recovery rate. Furthermore, the sawdust and slabs were recorded as 2.92 m³ (7.90%) of sawdust and 7.11 m³ (19.24%) of slabs, respectively. There were a number of factors that decreased the magnitude of the lumber recovery rate. It was observed that cutting using a wider saw kerf caused a reduction in the rate of lumber recovery owing to the generation of an increased quantity of sawdust. The lumbers were air-seasoned in the sawmill yard. Maximizing the volume of the lumber recovered from the logs can increase the sawmill profitability, lessen the effects of climate change, ensure the sustainable use of natural resources, enhance the energy efficiency and manage wood waste (e.g., recycling and prevention) for green economic development and industrial transformation. This species has a great demand in the wood industry of Ethiopia; hence, the plantation and yield of C. lusitanica must be expanded in order to provide sustainable forestry, protect valuable forest resources and safeguard the biodiversity in the country. Full article

In addition to traditional chip methods, performance lasers are often used in the field of wood processing. When cutting wood with CO₂ lasers, it is primarily the area of optimization of parameters that is important, which include mainly laser performance and cutting speed. They have a significant impact on the production efficiency and cut quality. The article deals with the use of an artificial neural network (ANN) to predict spruce wood cut characteristics using CO₂ lasers under several conditions. The mutual impact of the laser performance (P) and the number of annual circles (AR) for prediction of the characteristics of the cutting kerf and the heat affected zone (HAZ) were examined. For this purpose, the artificial neural network in Statistica 12 software was used. The predicted parameters can be used to qualitatively characterize the cutting kerf properties of the spruce wood cut by CO₂ lasers. All the predictions are in good agreement with the results from the available literary sources. The laser power P = 200 W provides a good cutting quality in terms of cutting kerf widths ratio defined as the ratio of cutting kerf width at the lower board to the cutting kerf width at upper board and, therefore, they are optimal for cutting spruce wood at 1.210⁻² ms⁻¹. Full article

Sash gang saws with narrow-kerf saw blades are used in the production of glued laminate flooring elements in plants where dry technology is applied. This means that boards or friezes are sawn into top layer lamellae in dry conditions (moisture content of about 10–12%) from expensive wood species, often exotic. The object of this research was stellite-tipped teeth of narrow kerf saw blades sharpened under industrial conditions. A NIKON ECLIPSE Ti-S microscope equipped with a NIKON DS-Fi2 recording camera was used to take pictures of teeth, which were analysed in a graphical software to measure the radii of the main cutting edges. The high-quality images obtained were used to determine the values of the rounding radii of the cutting edges. It was noted that the quality of edges regenerated in industrial conditions, some of which had chipping, was lower than that of brand new saw blades. Full article

This article deals with the laser cutting of wood and wood composites. The laser cutting of wood and wood composites is widely accepted and used by the wood industry (due to its many advantages compared to, e.g., saw cutting). The goal of this research was to optimize the cutting parameters of spruce wood (Pices abies L.) by a low-power CO₂ laser. The influence of three factors was investigated, namely, the effect of the laser power (100 and 150 W), cutting speed (3, 6, and 9 mm·s⁻¹), and number of annual rings (3–11) on the width of the cutting kerf on the top board, on the width of the cutting kerf on the bottom board, on the ratio of the cutting kerf width on the top and bottom of the board, on the width of the heat-affected area on both sides of the cutting kerf (this applies to the top and bottom of the board), and on the degree of charring. Analysis of variance (ANOVA) and correlation and regression analysis were used for developing a linear regression model without interactions and a quadratic regression model with quadratic interactions. Based on the developed models, the optimization of parameter settings of the investigated process was performed in order to achieve the final kerf quality. The improvement in the quality of the part ranged from 3% to more than 30%. The results were compared with other research dealing with the laser cutting of wood and wood composites. Full article