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.