Efects of plasma treatment and sanding process on surface roughness of wood veneers

Abstract

An ideal veneer surface is crucial for good panel properties in plywood manufacturing. Te aim of this study was to compareplasma treatments and sanding (mechanical) processes with respect to the surface roughness of veneers. Rotary-cut veneers with athickness of 2 mm from Scots pine (Pinus sylvestris ) logs were used as material. Afer rotary peeling, veneer sheets were dried at 110°C in a veneer dryer. Veneer sheets were divided into 4 main groups. Te surfaces of the control veneer sheets were lef untreated. Twodiferent grits of sandpaper, 80 and 180, were used for sanding the surfaces of veneers. Plasma treatment was applied to the last veneergroup with 3 diferent gases (oxygen, nitrogen, and ammonia) and 3 diferent plasma times (1 min, 5 min, and 15 min). Te MitutoyoSurfest SJ-301 instrument was used to determine surface roughness of samples. Average roughness (Ra), mean peak-to-valley height(Rz), and maximum roughness (Rmax) parameters were measured to evaluate the surface roughness of the samples based on DIN 4768.It was found that the smoothest veneer surfaces were obtained with the sanding processes. Surface roughness values (Rz) of veneersheets sanded with 180 grit sandpaper were lower than those of veneers sanded with 80 grit sandpaper. Compared with the plasmatreatment in terms of surface roughness, plasma-treated veneers had higher Rz values. It was also determined that Rz values werethe lowest in the veneers treated with nitrogen plasma. Additionally, the surface roughness values of Scots pine veneers treated withammonia plasma were a little higher than those of veneer sheets treated with oxygen plasma. Te efect of plasma treatment time onsurface roughness was not found to be statistically signifcant.