Thermal modification improves the properties of wood, especially its stability and durability. We thermally treated spruce wood with the Thermowood process at three temperatures (160 °C, 180 °C, and 210 °C) and subjected it to accelerated aging in wet mode. We evaluated the chemical composition (wet chemistry, infrared spectroscopy), color, surface morphology, and wetting of the wood surface with water. Thermal treatment caused a significant decrease in hemicelluloses (up to 72.39% at a temperature of 210 °C), which initiated an increase in the content of more resistant wood components—cellulose and lignin. With accelerated aging, the hemicellulose content decreased by another 5%. The most significant differences between the infrared spectra of thermally modified wood before and after exposure to accelerated aging were in the absorption bands of lignin (1509 and 1596 cm⁻¹) and in the region of carbonyl groups between 1800 and 1630 cm⁻¹. Thermal treatment also caused a change in the color of the wood to dark brown; the overall color difference ΔE increased several times. The thermal-induced shortening of polysaccharide fibers and reduction in their width were even more manifested during accelerated aging. This work contains new knowledge about the properties critical for the reuse of thermally modified wood after accelerated aging, simulating the end of its life cycle.

The presented paper deals with a mutual comparison of the roughness of the sanded radial surface after an eccentric and a belt sander. The beech wood (Fagus sylvatica L.) was sanded with an eccentric sander ETS 125 REQ-PLUS and a belt sander BS-75 E-set from Festool with the grit sizes P40, P60, P80, P100, P120 and P150. The evaluation of the roughness parameters Ra, Rp, Rv, Rz, and Rt was carried out using a digital microscope with a 2.5 mm L-filter and an 8 μm S-filter under the conditions of the technical standard STN EN ISO 21920. The measured results were supported using microscopic analysis of the surface topography especially for surfaces with very high roughness. The experiment shows a lower surface roughness of beech wood sanded with an eccentric sander. The sander created a surface with smaller grooves, removed more protruding fibers and created a more homogeneous surface suitable for subsequent surface treatment.

The paper aims to determine by measuring whether the Thermo-Vacuum modification of selected types of wood causes an increase or decrease in surface roughness after its sanding using drum sander. The roughness change is explained more comprehensively with respect to the change in density and hardness. The surface roughness was measured with a Keyence VHX-7000 digital microscope. The measured data showed that the Thermo-Vacuum modification reduced the surface roughness of beech wood. On the other hand, pine, oak, and chestnut wood increased in roughness probably due to a decrease in their hardness. This caused deeper grooves to be cut in the sanding process. The paper thus answers the question of whether wood modification helps the woodworking processes to achieve lower surface roughness or, on the contrary, increases it, which will require further surface treatments.

Attaining optimal milling conditions in industrial applications presents a significant challenge. This paper investigates the influence of feed speed and rotational speed in CNC milling on plywood surface quality. Furthermore, it aims to optimize these parameters to minimize surface roughness and associated defects. The roughness parameters (Ra, Rz, Rp and Rv) were quantified using a Keyence VHX-7000 digital microscope. In addition to surface roughness analysis, delamination of veneers and the origins of surface irregularities were microscopically analysed. The polynomial regression models for Ra and Rz were subsequently developed to identify optimal milling conditions. At rotational speed of 20,000 rpm and at feed speed of 10 m min⁻¹ the lowest roughness was achieved. However, very rough fuzzy surface with kinematic traces of the tool, delaminated veneers and torn fibres had occurred at rotational speed of 12,000 rpm and at feed speed of 18 m min⁻¹. These results were supported by investigating the effect of feed per tooth and chip thickness on surface roughness. The highest coefficient of determination was observed between feed per tooth or chip thickness and Rp parameter. The main outcome of this paper was the identification of the most optimal combinations of technological parameters, considering the overall condition of the plywood surface.

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.