Several previous studies have investigated the effects of heat treatment on the chemical composition, along with the physical and mechanical properties, of wood from various species. However, the effects of these property changes upon the machining properties and surface quality of machined wood have been studied much less. The main goal of this work was to investigate the comparative cutting power consumption during milling and the resulting surface roughness of heat-treated and untreated beech wood (Fagus sylvatica L.). Several cutting regimes were tested by combining different values of rotation speed, feed speed, and cutting depth. The cutting power and the processing roughness were assessed and compared. The results clearly showed that the cutting power involved in the milling of heat-treated beech wood was up to 50% lower than that of untreated wood, but the processing roughness was slightly higher.

Color and chemical changes were investigated in beech wood (Fagus sylvatica L.) following light steaming and further heat treatment for 2.5 h at 200 °C by two techniques (industrial ThermoWood versus a laboratory procedure in the presence of air). Colour changes were evaluated in the CIE Lab system, while Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) investigation was employed to highlight and compare the associated chemical changes. Light steaming caused only minor chemical changes (limited hydrolysis of hemicelluloses) not ready detectable by FTIR. In contrast, heat treatments caused visible changes in the FTIR spectra, especially in the region 1800 to 1500 cm . A significant variation of the ratios of relevant absorption bands indicated complex chemical changes, including hydrolytic, oxidative, and condensation reactions. FTIR ratios and the mass loss values in the two heat treatments relate, both indicating a more advanced modification in the case of the ThermoWood process.

The comparative behavior of heat-treated and untreated beech wood (Fagus sylvatica L.) were studied in response to planing. Beech wood samples were heat-treated in an electric oven without air circulation, at atmospheric pressure, at 200 °C for 1, 2, 3, 4, 5, or 6 h. After conditioning, both the heat-treated samples and the untreated controls were planed at a rotation speed (n) of 4567 rpm and a feed speed (u) of 10 m/min via a "silent power" cylindrical cutter. The cutting power was measured during machining by a Vellemann DAQ board. After processing, the surface quality was measured along and across the cutting direction with a stylus MarSurf XT20 instrument, and the processing roughness was assessed by the roughness parameter Rk. The influence of the heat-treating duration upon the cutting power and the processing roughness were analyzed and correlated to the mass loss after the heat treatment. Linear regression functions were generated for both of the correlations.