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The subject of this paper is the analysis of the influence of laser cutting of oak wood on its drying process. The subject of the research was the comparison of the drying process and the quality of the dried wood in samples cut by classical technology (sawing) and samples cut with the use of laser. The research was carried out on two sets of samples which were subjected to an identical drying process. Continuous moisture loss and final moisture attained, moisture gradients before and after drying, and internal tensions before and after drying were monitored by means of the fork test and the cut-test. The final moisture content at the end of drying was 8.09% for the saw-cut samples and 8.22% for the laser-cut samples, a difference of only 0.13%. The analysis of the individual characteristics observed showed that the influence of the cutting technology did not have a significant effect on the drying process or the quality of the dried oak sawn timber.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The paper deals with the fire technical characteristics of insulation panels made of recycled technical textiles from the automotive industry. The introductory part focuse an of the use of recycled textiles, a description and division of technical textiles, a description of the examined material and its composition, combustion processes, and the method of handling waste textiles. The monitored characteristics were the determination of the ignitability of the material, the gross calorific value as well as the radiant heat resistance. The measurements were carried out on samples from recycled technical textiles before and after their treatment with flame retardants (Isonem Anti-fire Solution, Ecogard B45, HR Prof, woven carbon foil, non-woven carbon foil). The best results in the ignitability test after treatment with liquid flame retardants were obtained after treatment with Ecogard B45. The results show that when flame retardants are used, the released heat during the combustion of the monitored materials treated through the dipping method is significantly lower from 13.7 MJ/kg to 23.7 MJ/kg. The lowest gross calorific values were achieved when using liquid flame retardant HR Prof when applied by dipping. The proportion of material that did not burn was very low (4.61 to 5.63%). After exposure to radiant heat for 10 min, the highest mass loss was 13.6% (dipping in Ecogard B45) and the smallest 1.8% (non-woven carbon foil). Based on results, it shows that flame retardant ECOGARD® B45 for the insulation material Senizol AT XX2 TL60 made from recycled technical textiles is the most suitable fire protection. [ABSTRACT FROM AUTHOR]

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 1.2·10−2 m·s−1. [ABSTRACT FROM AUTHOR]

This research work aims to investigate the effects of thermal modification and wood cutting direction (transverse, radial and tangential) on the content of extractives, lignin, cellulose, and hemicelluloses, and on the thermal conductivity of Norway spruce (Picea abies L.) wood. Samples were thermally modified for 3, 6, and 9 h at temperatures of 160°C, 180°C, and 200°C in the oxidizing atmosphere with natural convection. The extractives, lignin, cellulose, and holocellulose contents were determined by wet chemistry methods, the structural changes were evaluated by using Fourier-transform infrared spectroscopy (FTIR). The highest relative content of extractives was determined at the temperature of 200°C and a thermal modification duration of 9 h. The lignin content decreased at the temperature of 160°C and increased at higher temperatures due to the formation of pseudo-lignin. The cellulose content increased, and hemicellulose content decreased with the increased temperature and thermal modification duration. FTIR analyses revealed changes mainly at the temperature of 200°C, primarily a decrease in the intensities of the characteristic absorption bands of lignin due to degradation reactions. Markedly, density and thermal conductivity decreased mostly due to depolymerization of hemicelluloses. Regarding the thermal conductivity, a slightly higher decrease in transversal and tangential sections was determined. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The quality of milled surface medium-density fibreboards (MDF) and the effect of the wrong milling direction during the process of automatic milling in real conditions in practice (production machine, production tool, and material) are presented in the paper. Moreover, the effect of the double vs. single bladed milling cutter on the final surface quality with the simultaneous changes in individual parameters of feed rate, thickness of the removed layer, and cutting direction was investigated. The MDF was separated using the strategy “one per pass“ with required cutting direction (climb or conventional) and the required thick strips cutting off (4 mm to 16+ mm) at a constant operation speed of the milling cutter (n = 20000 min−1) and a changing feed rate from vf = 1 m/min−1 to vf = 5 m/min−1. The use of a multi-bladed milling cutter resulted in the higher quality of the milled surface in all cases (change in feed rate, thickness of removed layer, and cutting direction). The effect of the wrong milling direction during automatic milling was observed only for a single-bladed milling cutter used. An increase in surface roughness (Ra) occurred; therefore, using the double-bladed milling cutter, which was not associated with an increase in surface roughness, is recommended. [ABSTRACT FROM AUTHOR]

The issue of the change in tool temperature as a result of the machining process is presented in this paper. The aim of the paper is to put forward a proposal and subsequently to verify the methodology of temperature monitoring in the process of computer numerical control (CNC) machining in real time. Subsequently, the data can be used in the process of adaptive machine-tool control. Experiments were used to determine whether the research method is appropriate. Oak, beech and spruce wood turning blanks with the thickness of 20 mm were machined using a 5-axis CNC machining centre. A temperature change observation resulting from the changes in parameters of the removed layer was used to test whether the research method is relevant. Parameters of the removed layer were affected by the changes in feed rate in the range from 1 ÷ 5 m·min−1 in the removed layer (1–5 mm) or in wood species used in the experiment. As emerges from the proposed methodology, it is possible to monitor the changes in tool temperature responding to minimal changes in technological parameters on a relatively small size of a milled surface quite accurately. Sensitivity to given changes in technological parameters as well as the importance of the methodology was proven. [ABSTRACT FROM AUTHOR]