Étude de trois procédés de finition des surfaces du bois d'érable à sucre pour fins de vernissage

Liste des illustrations

• Figure 1– 1 . Principaux types de coupe orthogonale (d'après Hoadley 2000)
• Figure 1– 3 . Copeau de type I obtenu en direction 90°-0°, à un angle d'attaque de 25° et à 1,14 mm de profondeur de coupe (tiré de Woodson et Koch 1970)
• Figure 1– 4 . Copeau de type II, obtenu en direction 90°-0°, à un angle d'attaque de 15° et 1,14 mm de profondeur de coupe (tiré de Woodson et Koch 1970)
• Figure 1– 5 . Copeau de type III, obtenu en direction 90°-0°, à un angle d'attaque de 5° et 1,14 mm de profondeur de coupe (tiré de Woodson et Koch 1970)
• Figure 1– 6 . Schéma montrant la position de l' arête tranchante du couteau en coupe orthogonale et en coupe oblique
• Figure 1– 7 . Variation du rayon de l' arête tranchante en fonction de l'angle oblique ( i )
• Figure 1– 8 . Variation de l' angle d' attaque du couteau en fonction de l' angle oblique ( i )
• Figure 1– 9. Coupe du bois en utilisant une barre de pression et un couteau fixe (d'après Stewart 1986)
• Figure 1– 10. Schéma illustrant la coupe périphérique en opposition (adapté de Wengert 1988)
• Figure 1– 11 . Porte-outil hélicoïdal: ø est l'angle d'hélice et L est la distance axiale entre rangées adjacentes de couteaux (tirée de Stewart 1975b)
• Figure 1– 12 . Géométrie de la coupe périphérique hélicoïdale et de celle à couteaux droits (adapté de Stewart 1975b)
• Figure 1– 13 . Comportement des forces de coupe en fonction du temps, pour un porte-outil hélicoïdal (adaptée de Stewart 1975b)
• Figure 1– 14 . Divers niveaux de fil arraché à la surface de l'érable à sucre (tirée de ASTM D 1666 1987)
• Figure 1– 15 . Divers niveaux de grain laineux ou pelucheux à la surface du sapin Engelmann (tirée de ASTM D 1666 1987)
• Figure 1– 16 . Marques de copeaux à la surface du bouleau jaune (tirée de ASTM D 1666 1987)
• Figure 1– 17 . Goutte d'un liquide en équilibre (à droite) (adaptée de Rozumek et Elbez 1985) et énergies du système (à gauche) (adaptée de Good 1993)
• Figure 2– 1. Schema showing sample dimensions used for each test.
• Figure 2– 2. Tangential surface of sugar maple wood peripherally planed with a freshly sharpened knife.
• Figure 2– 3. Tangential surface of sugar maple wood sanded with a 120-180 grit program.
• Figure 2– 4. Transverse SEM micrograph of a sugar maple surface peripheral planed with a freshly sharpened knife and coated with polyurethane.
• Figure 2– 5. Transverse SEM micrograph of a sugar maple surface sanded with a 120-180 grit program and coated with polyurethane.
• Figure 2– 6. Adhesive failure of PU coating caused by the razor blade during SEM preparation. Arrows indicate vessels filled with PU sealer. Apparently, the extent of penetration was not sufficient to obtain satisfactory adhesion.
• Figure 2– 7. Typical matched planed (P) and sanded (S) specimens showing different conditions after accelerated aging.
• Figure 2– 8. Pull-off test dollies showing the coating interfaces holding fibers pulled out from the surface. At the left-hand side, four representative dollies pulled-off from planed surfaces (P); at the right-hand side, four dollies pulled-off from sanded surfaces (S).
• Figure 3- 3. Overall normal cutting force ( F _N ) for cutting sugar maple wood with a fixed-knife pressure-bar system, as a function of cutting depth (a) and rake angle (b), for three oblique angles (bars show standard errors).
• Figure 3- 4. Parallel cutting force ( F _P ) for cutting sugar maple wood with a fixed-knife pressure-bar system, as a function of cutting depth (a) and rake angle (b), for three oblique angles (bars show standard errors).
• Figure 3- 5. Lateral cutting force ( F _L ) for cutting sugar maple wood with a fixed-knife pressure-bar system, as a function of cutting depth (a) and rake angle (b), for three oblique angles (bars show standard errors).
• Figure 3- 6. Tangential surfaces of sugar maple cut with a fixed-oblique knife pressure-bar system. Multiseriate ray presenting splits parallel to the knife cutting edge (0.25-mm cutting depth; 25º α; 30º i ) (a). Rays that underwent ruptures by bending below the cutting plane (0.75-mm cutting depth; 25º α; 30º i ) (b). Rays severed in the cutting-plane level at the highest α level (0.25-mm cutting depth; 55º α; 30º i ) (c). Region where group of cells have been pulled out by lateral forces at the highest i level (0.25-mm cutting depth; 55º α; 70º i ) (d).
• Figure 3- 7. Proportion of samples with machining defects as a function of cutting depth and i (α pooled, n = 80) (a). Proportion of samples with machining defects as a function of α and i , for a 0.25-mm cutting depth (n = 20) (b).
• Figure 3- 8. Transverse SEM micrographs of sugar maple cut with a fixed-oblique knife pressure-bar system. At low cutting depth and α, the propagation of cracks below the cutting plane was inhibited by the pressure-bar action, limiting the defect to slight fuzzy grain (0.25-mm cutting depth; 25º α; 30º i ) (a). Superficial cell damage was not visible transversally even for the hardest cutting conditions (0.75-mm cutting depth; 25º α; 30º i ) (b).
• Figure 3- 9. Total wetting time (a) and k-value (b), using water as probe liquid, obtained in sugar maple surfaces cut with a fixed-knife pressure-bar system at a 0.25-mm cutting depth, as a function of α, for three i levels.
• Figure 4– 1. Macroscopic view of sugar maple helical-planed boards. At the left-hand side, a surface obtained by helical planing oblique to the grain; at the right-hand side, a surface produced by helical planing across the grain.
• Figure 4– 2. Proportion of samples with torn grain (left y-axis) and maximum defect depth (right y-axis) as a function of feed speed for helical planing oblique to the grain (cutting depths pooled).
• Figure 4– 3. Tangential surfaces of sugar maple helical-planed oblique to the grain. Low (a) and relatively severe (b) tearing out of vessel walls; sound cut vessels, rays and fibers (c); predominance of plateau-like zones, torn-out vessel walls and relatively crushed rays (d).
• Figure 4– 4. Transverse SEM micrographs of sugar maple surfaces produced by helical planing oblique to the grain at increasing feed speeds. Smooth surface obtained at 5.5 m/min feed speed (a); higher roughness and slight tearing out of cells (arrows) at 10.0 m/min feed speed (b).
• Figure 4– 5. Tangential surfaces of sugar maple helical-planed across the grain. Low (a) and relatively high (b) levels of fibrillation; neighboring cells pushed into vessels (a-c); severe separation of vessel walls and incompletely severed rays (c-d).
• Figure 4– 6. Transverse SEM micrographs of sugar maple surfaces produced by helical planing across the grain. Valley left by a group of fibers torn-out from middle lamella (a); group of torn-out fibers remaining attached to the workpiece (b).
• Figure 4– 7. Transverse SEM micrographs of sugar maple surfaces produced by helical planing across the grain. Rays presenting ruptures by bending below the cutting plane (a-b); multiseriate ray with rupture deeper than in uniseriate ray (a); arrow indicates a multiseriate ray and neighboring cells completely removed from the surface at the highest feed speed (b). Neighboring cells pushed into vessels at the lowest feed speed (c); arrow indicates tissues completely removed near a vessel at the highest feed speed (d).
• Figure 5– 1. Roughness average (R_a) as a function of sanding program for two abrasive minerals and two directions of roughness measurement (feed speeds pooled).
• Figure 5– 2. Roughness average (R_a) as a function of feed speed for two abrasive minerals and two directions of roughness measurement (grit sizes pooled).
• Figure 5- 3. Tangential surfaces of sugar maple sanded with 100-grit silicon carbide presenting relatively low fibrillation at 8 m/min feed speed (a) and high fibrillation at 14 m/min feed speed (b). This behavior was observed for the three sanding programs and for both types of abrasive minerals.
• Figure 5- 4. Transverse SEM micrographs of sugar maple sanded with 100-grit aluminum oxide. At 8 m/min feed speed, uncut multiseriate rays are usually bent and crushed (arrow) (a), whilst at 14 m/min feed speed these rays may remain raised, leaving peaks (b).
• Figure 5- 5. Transverse SEM micrographs of sugar maple sanded with silicon carbide at 8 m/min feed speed. The attenuation of roughness profile from the 100-grit (a) to the 100-120-150-grit sanding program (b) is noticed.
• Figure 5- 6. Maximum depth of damage of sugar maple surfaces as a function of sanding program for two abrasive minerals (feed speeds pooled).
• Figure 5- 7. Total time for complete surface wetting by water and surface energy as a function of the sanding program for sugar maple sanded with aluminum oxide (four feed speeds pooled).
• Figure 5- 8. Total time for complete surface wetting by water and surface energy as a function of feed speed for sugar maple sanded with aluminum oxide (three sanding programs pooled).
• Figure 6- 1. Transverse SEM micrograph of a sugar maple surface sanded with a single-stage 100-grit program and coated with polyurethane.
• Figure 6- 2. Transverse SEM micrograph of a sugar maple surface sanded with a 100-120-150-grit program and coated with polyurethane.
• Figure 6- 3. Transverse SEM micrograph of a sugar maple surface cross-grain helical-planed and coated with polyurethane. Arrow indicates a multiseriate ray with a rupture below the cutting plane.
• Figure 6- 4. Transverse SEM micrograph of sugar maple surfaced by fixed-oblique knife pressure-bar cutting and coated with polyurethane.