Annals of DAAAM for 2011 & Proceedings of the 22nd International DAAAM Symposium, Volume 22, No. 1, ISSN 1726-9679 ISBN 978-3-901509-83-4, Editor B. Katalinic, Published by DAAAM International, Vienna, Austria, EU, 2011 Make Harmony between Technology and Nature, and Your Mind will Fly Free as a Bird Annals & Proceedings of DAAAM International 2011 EFFECT OF ADHESIVE STRENGTH OF BONDED AREA SURFACE OBUCINA, M[urco]; SMAJIC, S[elver] & SKALJIC, N[edim] Abstract: This paper presents the research of the impact of different types of adhesives on bond strength before planed surface of beech, fir, oak and thermally modified beech-wood (220°C) samples. The samples were planed in the radial direction. Tools for planing had a double-edged, planed and the displacement at a speed of 12 m/min. The depth of the milling operation was 1.00 mm, rake angle blade tool was γ = 15 °, at 6000 ° / min. Diameter of the cutting edge was Φ = 125 mm. The samples are glued with waterproof glue and two to PVAc glue and PU glue. The lowest tensile strength of the samples were thermally treated beech glued with PVAc adhesive, then fir, oak and the largest were beech samples. The lowest tensile strength in the samples glued with PU glue had a fir, then oak and the greatest strength of had thermally modified beech and beech. The lowest shear strength had samples of thermally modified beech glued with PVAc glue, then oak, fir, and most specimens of beech. The lowest tensile strength in the samples glued with PU glue had thermally modified beech, oak and then had the greatest strength of beech and fir Keywords: PU glue, PVAc glue, bonding, bonding strength, planing 1. INTRODUCTION The technological processing of wood glue holds very important place. It significantly affects the practical value and quality of wood products. During bonding simultaneously and in parallel to place more complex physical and chemical processes, which are a consequence of the properties of wood and glue, the interaction between wood and glue, and elements of the technological process. The main goal when gluing wood to achieve a combination of high strength and long lasting strength, which in principle should not be less that the strength of the wood. The strength of the glued joint a lot depends on the interaction between wood and adhesives, and adhesion of the adhesive. The lowest tensile strength in the samples glued with PU glue had a fir, then oak and the greatest strength of had thermally modified beech and beech. The lowest shear strength had samples of thermally modified beech glued with PVAc glue, then oak, fir, and most specimens of beech. The lowest tensile strength in the samples glued with PU glue had thermally modified beech, oak and then had the greatest strength of beech and fir. In addition the adhesion properties of adhesives significantly affect the quality of surface finish and wood. Wetting (spreading glue on the surface of wood depends directly from the geometry of the surface). On the other hand, all the bumps on the surface of the wood creates an uneven layer of glue and create internal tension in the merge (pressing) of wood surfaces to be bonded. Tests show that a smooth surface requires a relatively small amount of coating for surface protection (Aydin, 2004 and Marian et al, 1958).The quality of machined surfaces of wood depends on the anatomical structure (tree species), and cutting parameters (depth of operation, velocity, displacement, rotation number of tools, interventions by the blade and blade angle. It is assumed that the surface roughness of cut surfaces softwood sawmills and increasing radius of the wedge (Kenturakis & Juodeikiene, 2007; Gindl & Tschegg, 2002 and Obucina et al., 2010) 2. MATHERIALS AND METHODS . Experimental measurements were performed on samples of oak, fir, beech and thermally modified beech. The dimensions of the original samples before planing and gluing were: 70x21x600 mm steamed beech, oak and fir, a 70x21x500 mm thermally modified beech. Moisture content of samples was: 9.18% Steamed Beech, Fir 18.27%, 9.31% Oak, Thermally modified beech 4.47%. Samples were radial texture, before planing were conditioned at 20° C and relative humidity of 65 ± 5%. Investigations were conducted on samples who planed in the radial direction. Manufacturer of glue is Kleiberit Germany. According to technical specification glue properties are: one component D4 waterproof glue for bonding according to DIN/EN 204 KLEBIT 314 PVAc glue and PUR Leim 501 PU glue. Planing is done to PowerMat 400 machine, which had a cutting tool with two blades. Planed at the speed of displacement of 12m/min. Planing thickness was 1.00 mm. The number of revolutions was 6000°/min, a rake angle 15° blade. Bonding the samples was carried out in a star pres. Regimes were applied by glue manufacturer's recipe: application with the adhesive was 150 g/m 2 , pressing pressure 0.7 MPa. Once we have samples that are bonded out of the presses, we left them to be conditioned for seven days, before proceeding with further processing thereof. The temperature at the facility where the samples were bonded with PVAc adhesive was 19°C and relative humidity 49%. After the samples conditioned we accessed on the crop specimens for testing shear strength and tensile strength according to EN 204. The study was carried out on Zwick testing machine. Fig. 1. Star press used in experiment 0343