Linear friction welding for wood, a parameters study for up-scaled assemblies

Linear wood welding is a promising technology which allows holding two wood pieces together by heating the surfaces by a lineal frictional movement between them. It's well known that welding parameters as well as wood anatomical, chemical and physical features are the basis of the welded wood properties. This study presents a window of parameters to weld beech and spruce, separately. For beech, welded pieces had 500x80x24mm3. The studied parameters were: welding pressure and amplitude, maintaining a constant frequency, welding time, holding time and holding pressure. The obtained shear strength values were near 10MPa, which already satisfy the minimal requirement for structural applications. For spruce, welded pieces had 500x50x28mm3. The studied parameters were: welding pressure, welding time, holding time and holding pressure, maintaining a constant frequency and amplitude. The obtained shear strength values were around 3.5MPa. The different performance of these two wood types is analyzed and linked to the basic wood properties using X-Ray densitometry, temperature measurements and FE-SEM images. This work deals with joins of 8 and 13 times the surfaces welded in former studies. Therefore, it is the basis for further researches which aim to weld pieces of wood of big dimensions with minimal mechanical properties that allow using this technology on industrial applications.