WOOD WELDING

The term "wood welding" designates what can be defined as "welding of wood surfaces". This new process, that it provides the joint of wood pieces without the use of adhesives or any other additional material, provokes growing interest in the academic environment, although it is still in laboratorial state. Linear friction welding induced bymechanical vibration yields welded joints of flat wood surfaces. The phenomenon of the welding occurs in less time than 10 seconds, with the temperature in the rubbed surfaces reaching 170 oC, and the consequent change of state of the lignin and hemicelluloses, that then melt and flow. The process results in the detachment of wood cells, and in a formation of a fibers entanglement network immersed in a matrix of molten material which then solidifies. Scanning electron microscopy micrographs obtained shows a considerable physic-chemical reorganization in the bulk of the joint. This new composition of detachment wood cells/fibers of the two surfaces, a entanglement network immersed in a matrix of molten polymericmaterial, mainly melted lignin, yields in the interface of the welding a bond of considerable strength.