The effect of impregnation process on screwing withdrawal strength in wood material

In this study, the effect of impregnation process on screw withdrawal strength in wood materials was researched. In this regard, the woods that are most commonly used in furniture industry were used, such as; scotch pine (Pinus sylvestris Lipsky); oak (Quercus petreae Lipsky); and oriental beech (Fagus orientalis Lipsky). The wood materials were impregnated with borax, boric acid, borax+boric acid, imersol-aqua and timbercare-aqua in accordance with the conditions mentioned in ASTM-D 1413, TS 344 and TS 345. The impregnated samples were subjected to screw withdrawal strength tests at two different diameters (3,5x50 mm and 4x50 mm) in accordance with TS EN 13446. At the end of the tests, it was observed that the highest withdrawal strength was obtained in oak (41,41 N/mm2), and the lowest withdrawal strength was obtained in scotch pine (27,81 N/mm2); according to impregnated materials, the highest withdrawing strength was obtained in Ba (36,80 N/mm2); the lowest withdrawing strength was obtained in Iau (35,52 N/mm2). With respect to the screw diameter, the highest withdrawing strength was obtained in VI (37,21 N/mm2), and the lowest withdrawing strength was obtained in V2 (34,99 N/mm2). With respect to the screwing direction, the highest withdrawing strength was obtained at the surface (42,01 N/mm2), and the lowest withdrawing strength was obtained at the cross section (31,77 N/mm2). In accordance with the interaction of the factors such as the wood type, impregnated materials, screw diameter and the connection direction, the highest withdrawing strength was found at M+Bx+V1+Yu (57,14 N/mm2), and the lowest withdrawing strength was found at C+Iau+V1+Ma (22,56 N/mm2). In this regard, it was seen that the impregnation process increased the screw withdrawal strength. It can be said that, in the applications, the pieces that are impregnated with Bx and connected with V1 at the surface shall display the highest strength.