WOOD RESEARCH Volume 67, Number 6, 2022
Ondřej Dvořák, Miloš Pánek, Monika Sarvašová Kvietková, Filip Pastierovič, Irena Štěrbová, Kryštof Kubista, and Lukáš Sahula

Influence of wood species on quality of exterior transparent acrylic coating during outdoor exposure

Coating systems are a popular way to protect wood against the effects of weathering when used outdoors. This study evaluates the impact of the basic wood species on the overall durability and color fastness of the selected water-based acrylic exterior paint. Spruce (Picea abies L.) and oak (Quercus robur L.) wood samples were subjected to external weathering according to EN 927-3 (2000) for 6 and 12 months. The evaluation by instrumental methods related to co changes in color, gloss, surface wettability contact angle, at which paint damage was also visually evaluated. The results showed that the durability of the tested coating was higher for spruce. Still, on the other hand, thanks to its lighter shade, a significant color change caused by the base wood’s photodegradation was detected, showing that oak wood has a negative effect on the overall life of the tested coating.

WOOD RESEARCH Volume 66, Number 6, 2021
Monika Sarvašová Kvietková and Miroslav Gašparík

Surface irregularities of oak wood after transversal cutting with a circular saw

This paper deals with the effect of saw blade type (24, 40 and 60 teeth) and sawn distance on the primary profile (Pz) of tranvesre surface of European oak (Quercus robur L.) after transversal cutting. Transversal cutting was provided at constant cutting speed vc = 62 m.s-1 and with manual feeding using circular saw blade. An additional parameter was to determine the maximum sawn distance for each type of saw blade up to the point where the saw blade overheated, as well as the beginning of the blackening of the wood surface. The highest values of the primary profile (Pz) were achieved with a saw blade with 24 teeth, lower values were measured on wood cut with a 40 tooth blade and the lowest values after cutting with a 60 tooth blade. As the saw distance increased, there was no rapid and steep increase in the primary profile values, but these values gradually increased slightly, probably due to the gradual blunting of the tool.

WOOD RESEARCH Volume 61, Number 1, 2016
Milan Gaff, Monika Sarvašová Kvietková, Miroslav Gašparík, and Martin Slávik

Dependence of roughness change and crack formation on parameters of wood surface embossing

This paper deals with roughness change and crack formation after surface embossing of aspen wood. Embossing was carried out with three various shapes of embossing wedges (convex, concave and with 45° angle). The embossing was realized with two temperatures, 20 and 160°C. The surface roughness before and after embossing was evaluated on the basis of the arithmetical mean deviation of the roughness profile, Ra. Surface quality measurements were carried out in perpendicular (transversal) and parallel (longitudinal) direction in relation to wood fibers. Embossment area quality was evaluated by the mean of portion of cracks in embossment. This evaluation was based on digital image of embossed area and subsequently calculation of portion of cracks area in relation to total evaluated area. Elevated temperature has a positive effect on the quality of the surface, because of roughness decrease. However, the increase in temperature causes a growth in the proportion of cracks on the embossed surface.

WOOD RESEARCH Volume 62, Number 5, 2017
Milan Gaff, Miroslav Gašparík, and Monika Sarvašová Kvietková

Evaluation of the wood surface quality depending on the parameters of embossing

This paper deals with changes in roughness and crack formation after surface embossing of aspen wood. Embossing was based on pushing a wedge with 45° angle into three embossing depths, i.e. 2, 4 and 6 mm. The surface roughness before and after embossing was evaluated on the basis of the arithmetical mean deviation of the roughness profile, Ra. Surface quality measurements were carried out in perpendicular (transversal), parallel (parallel) and perpendicular/parallel to the wood grain. (Embossment area quality was evaluated by the mean of portion of cracks in embossment). This evaluation was based on a digital image of the embossed area and a subsequent calculation of the portion of the cracked area in relation to the total evaluated area. Increasing the embossing depth has a positive impact on the quality of the embossed surface, i.e. the highest quality was generally achieved with an embossing depth of 6 mm. The worst surface quality was achieved with the perpendicular orientation of the wedge regardless of the direction of the roughness measurement.

WOOD RESEARCH Volume 62, Number 3, 2017
Miroslav Sedlecký and Monika Sarvašová Kvietková

Surface waviness of medium-density fiberboard and edge-glued panel after edge milling

This article deal with investigation of mean arithmetic deviation of the waviness profile (Wa) on edge surface after edge milling of medium-density fiberboard, medium-density fiberboard with single-sided lamination and spruce edge-glued panel. Edge milling afftected feed rate 4, 8, and 11 m.min-1 and cutting speed 20, 30, 40 a 60 m.s-1. There were used for milling 3 types of tungsteen carbide blades with different composition and treatment (HW1, HW2 and HW1 + CrTiN coating). Working results show that the lowest values of waviness were found with a spruce glulam. Considering the machined surface quality the most suitable blade is HW1, then HW1 + CrTiN coating and the worst one is HW2. The lowest measured values of Wa were found with the feed rate of 4 m.min-1 and cutting speed of 60 m.s-1. The increase in cutting speed resulted in the drop in the values of average Wa, while the increase in feed rate had the opposite effect.

WOOD RESEARCH Volume 63, Number 4, 2018
Miroslav Sedlecký, Monika Sarvašová Kvietková, Richard Kminiak, and Lukáš Kaplan

Medium-density f iberboard and edge-glued panel after edge milling – surface waviness after machining with different parameters measured by contact and contactless method

This article deals with the quality of the milled surface of board edges. The quality is evaluated using the Wa (mean arithmetic deviation of the surface waviness). The Wa was measured by two methods (contact and contactless). Form Talysurf 50 Intra was used for the contact method, and the LEXT 3D measuring laser microscope OLS4100 was used for the contactless method. The variable factors whose effect on the resulting waviness was determined were the machined material, milling cutters, cutting speed and feed rate. The boards used were medium-density fiberboard, medium-density fiberboard with single-sided lamination and spruce edge-glued panel. Three different cutters were used for the milling, all of which were made of sintered carbide, and one of them was coated (CrTiN). The cutting speeds were 20, 30, 40 and 60 m.s-1, and the feed rates were 4, 8 and 11 m.min-1. All the above-mentioned factors as well as their mutual interaction had an effect on the waviness. There was no significant difference between the two methods for determining the waviness. In terms of waviness, both methods are interchangeable.

WOOD RESEARCH Volume 63, Number 1, 2018
Lukáš Kaplan, Monika Sarvašová Kvietková, Adam Sikor, and Miroslav Sedlecký

Evaluation of the effect of individual paramaters of oak wood machining and their impact on the values of waviness measured by a laser profilometer

This article deals with determining the effect of different degrees of thermal modification, different cutting speeds (20, 30, 40 m. s-1), different feed rates (4, 8, 11 m. min-1) and different rake angles (15, 20 and 25°) with a 1 mm layer of removed material, on the quality of the surface of the workpiece using the mean arithmetic variation of the waviness profile „Wa“. The release was secured by setting the ruler and firmly holding it in the desired position. The ruler so configured was all the time to milling all the setting options.The article evaluates the process of planar milling of natural and thermally modified oak wood (Quercus cerris). For the evaluation, the samples were thermally modified by the Thermowood process at a temperature range of 160-210°C. The quality of the treated surface was evaluated after the planar milling process. The results obtained from this research show that by increasing the cutting speed during the machining of thermally modified and natural oak wood, we achieve better values of the mean arithmetic deviation of the waviness profile. The values of the monitored characteristic can also be improved by lowering the feed rate and selecting an appropriate rake angle. Thermal modification always lowers the values of the monitored characteristic.