An experimental study on productivity of curved laminated wooden elements in vacuum membrane presses

In this study, the usability of vacuum membrane press in laminated wooden furniture elements having variable curves were studied, the limit values of curves which can be applied on these elements were specified and the adhesion and mechanical performances of the laminated elements having such curves were determined. In the experimental samples, Oriental Beech (Fagus Orientalis Lipsky) in 1,5 mm. thickness European Oak (Quercus Petrea L.) and Scotch Pine (Pinus Sylvestris L.) with papel veneers were used. Papel veneers were pressed in 13 layers with five different radii (20-40-60-80-100 mm.), in three different width (50-100-150 mm.) with the help of two different structured (concave, convex) moulds prepared in ?L? shape in lamination method under vacuum membrane press machine. During the fastening procedure of the samples, PVAc dispersion D4 adhesive was used. Adhesion strength parallel and vertical to the layers, diagonal pressure, diagonal tensile strength and fatigue strength (rigidity- keeping the form) experiments were applied to the experiment samples. As a result of the study, vacuum membrane presses can be used instead of RF (Radio/high frequency) presses which carry various health risks and additionally which need double sided moulds with high cost but which are widely used in curved laminated wooden elements production in the national furniture sector and vacuum membrane presses don?t have the said disadvantages. One of the disadvantages of vacuum membrane presses was the membrane tear-off problem which was solved by using silicon based membrane instead of rubber based membrane. It was determined as s result that the lowest obtainable curve radius in laminated elements by using convex curve moulds was 40 mm., and the lowest obtainable curved radius was 200 mm. by using concave curved moulds. Among the experiment samples, the best adhesion quality were obtained in Oriental Beech samples. In relation to this, according to the results of the performance experiment, it was observed that laminated elements produced with using D4 adhesive and Oriental Beech papel veneer have better strength properties and ability to carry load. As a result, convex mould usage which was specified as giving better results in production of curved laminated wood under vacuum membrane press and as a wood type for papel veneers, Oriental Beech can be recommended.