The effect of boiling time on the surface roughness of rotary-cut veneers from oriental beech (Fagus orientalis L.)

The objective of this study was to investigate effects of boiling time on surface roughness of beech (Fagus orientalis L.) veneer manufactured using the rotary cutting method. Three logs of oriental beech were subjected to softening process by boiling them in water (60–70 °C) for various times (e.g. 20, 40, and 60 h) and they were peeled immediately. For surface roughness, veneer samples were taken from outer, center, and inner (near to pit) parts of logs and the distance of the locations where the samples were taken from the pith were the same. Veneer specimens have a dimension of 10 cm (width) by 20 cm (length) by 0.14 cm (thickness). Three roughness parameters, average roughness (Ra), mean peak-to-valley height (Rz), and maximum roughness (Rmax) for each group were measured according to DIN standard 4768 by using stylus profilometer and compared with one another. Except the boiling time, other factors (species, knife angle, peeling angel, etc.) were kept the same. The results show that, the surface of veneers, taken from heartwood and center of the logs boiled 60 h were significantly rougher than 20 and 40 h. But peeling veneers obtained from sapwood of logs boiled 20 h displayed significantly rougher surface than 40 and 60 h. For all samples, applying 40-h boiling period can minimize the roughness value. Therefore, it seems that 40-h boiling period is suitable in order to minimize the surface roughness of rotary-cut veneers manufactured from all of beech (F. orientalis L.) logs parts (inner, center, and outer).