Effect of welding parameters on the mechanical performance of pine-eucalyptus joints

Rotary friction welding (RFW) is a wood-joining technique that produces solid joints through frictional heat generated by controlled rotational speed and feed rate during the insertion of dowels into pre-drilled holes machined in substrates. This study evaluated RFW as a method for joining Eucalyptus spp. dowels to Pinus taeda substrates, important species from Brazilian plantation forestry. The welded interface microstructure was examined using scanning electron microscopy (SEM) and the effects of pre-drilled hole stage (single-stage and two-stage), rotational speed (1000 rpm and 1500 rpm), and feed rate (300, 400, and 500 mm·min−1) on the shear strength and dowel taper ratio were investigated to identify optimal RFW parameters. SEM analysis revealed fibre rupture and reorientation, indicating strong mechanical interlocking at the welded interface. Optimising the pre-drilled hole stage and rotational speed enhanced joint shear strength, whereas feed rate had a limited influence within the tested range. The evaluated process parameters produced similar dowel taper ratios across all tested conditions. A two-stage pre-drilled hole combined with a rotational speed of 1000 rpm is recommended for producing high-performance pine-eucalyptus welded joints by RFW.