Effects of cutting parameters on surface quality of paper birch wood machined across the grain with twoplaning techniques

Helical planing and face milling were applied across the grain to surface paper birch wood prior to coating application. Three feed speeds and three cutting depths were evaluated for face milling while three cutting depths were studied for helical planing. The roughness and wetting properties of wood as well as pull-off strength of a solvent-borne coating after aging were evaluated. For helical planing, no significant effects of the cutting depth on roughness and wetting properties were found. For face milling, the cutting depth had no significant effect on the surface roughness while it had a significant impact on the wetting properties. The feed speed affected significantly both parameters. Furthermore, none of these parameters had a significant effect on the pull-off strength. However, helical planing produced smoother surfaces with equivalent wetting properties and higher pull-off strength than face milling. Scanning electron microscopy showed more exposed cell lumina and sound cells for helical planed surfaces, which enhanced their wetting and adhesion properties.