This study aims to understand the phenotypic and genotypic correlations among wood anatomical, physical, and mechanical properties of hybrid poplar clones. Samples were taken from seven clones grown on three sites in Southern Quebec, Canada. Five trees per clone were randomly sampled from each site to measure anatomical (fiber length, fiber proportion, vessel proportion, fiber wall thickness, tension wood), physical (basic density, volumetric, longitudinal, tangential, and radial shrinkage), and mechanical wood properties (flexural modulus of elasticity (MOE), modulus of rupture (MOR), ultimate crushing strength parallel to the grain). The observed phenotypic and genotypic correlations between these wood properties were moderate to strong, except for fiber length and vessel proportion. Genotypic correlations for all wood properties were higher than for corresponding phenotypic correlations. Furthermore, fiber length showed weak correlations, whereas, vessel proportion showed strongly negative correlations with all other properties. Strong correlations were also found among fiber proportion, fiber wall thickness, basic density, and mechanical properties. Furthermore, results from this study show close genotypic and phenotypic correlations between fiber proportion, fiber wall thickness, and wood density, which consequently affect the mechanical performance of wood products. These findings indicate that there is a substantial opportunity to improve wood quality by selecting several wood properties for different end uses. © 2018 by the authors.

Fifteen stems of jack pine (Pinus banksiana Lamb.) coming from three commercial thinned (CT) plots (control, moderate, and intensive thinning) in the Abitibi-Témiscamingue region, Canada, were cross-cut into three 2.4 m length sections: bottom, middle, and top logs. Logs were processed with a chipper-canter at three cutting widths (CW 12.7, 19.1, and 25.4 mm), producing chips and a three faced cant. Chips were assessed by thickness, width, and length. Knot characteristics [total knot number (TKN) and area (TKA)] were assessed in the three cant faces. Growth ring attributes [earlywood density, latewood density (LWD), ring density (RD), earlywood proportion (EWP), ring width, and rings per mm], mechanical properties (shear, splitting, modulus of elasticity and modulus of rupture in bending), and basic density were evaluated on samples obtained within each CW area. The weighted mean chip thickness (WCT) was significantly affected by the log position in the stem (LPS) and CW. WCT increased as CW increased. Jack pine produce thicker chips than black spruce, when processed under the same cutting parameters. Thickness of chips coming from bottom and middle logs was similar due to a greater taper of the bottom log, which slightly increased this dimension. Thickest chips were produced in the top log due to a higher TKA and TKN towards the top of the stem. Multiple linear regressions showed that TKA, CW, and RD were significant predictors of WCT. Chip size distributions were significantly affected by the CT, LPS, and CW. Thinned stands logs appeared to produce smaller chips than natural stand logs. Moreover, chip thickness distribution was affected primarily by TKA and EWP, while the width and length distribution was mainly affected by EWP, LWD, and TKN. Chip size in jack pine is to some degree determined by knot attributes, growth ring characteristics, and wood density of the raw material. These results suggest the potential advantage of sorting logs prior to chipping, either by species, LPS and/or provenance (thinned or natural stands).

Fifteen stems of jack pine (Pinus banksiana Lamb.) of 3 commercial thinned plots (control, moderate, and intensive thinning) and 15 stems of black spruce (Picea mariana (Mill.) B.S.P), both coming from the Abitibi-Témiscamingue region – Canada, were cross-cut into three 2.4?m length sections: bottom, middle, and top logs. Logs were processed with a chipper-canter at three cutting widths (12.7, 19.1, and 25.4?mm), producing chips and a three-faced cant. The middle section of the cant was used to evaluate surface quality across the grain on each face. Roughness and waviness parameters and depth of torn grain were recorded. Knot characteristics were assessed in the three cant faces. Poorer surface quality was found in the lower part compared to the upper part of the cant for both species. At larger cutting widths, jack pine logs coming from a natural stand showed lower surface quality compared to logs from thinned stands. Black spruce waviness increased with the cutting width and stem height. These results were attributed to the increase of forces and vibration when cutting at larger cutting widths, which was worsened by the presence of bigger, more numerous knots at the control plot and in the top logs. Black spruce had deeper torn grain compared to jack pine. Their differences in knot characteristics resulted in a maximum torn grain depth favored by the presence of more knots rather than by bigger knot size. Other knot characteristics, such as the position of the knots in the cant face, the insertion angle of the branch and the distribution of the knots around the log, should be studied to better understand the relationship between torn grain formation and knottiness.

The effects of rake angle, cutting direction, and depth of cut on cutting forces and surface quality of black spruce were evaluated. Cutting forces were measured during cutting at four rake angles (35, 45, 55 and 65), four cutting directions (0 -90, 15 -75, 30 -60, and 45 -45), and three depths of cut (1, 2, and 3 mm). Torn grain, waviness, and roughness were evaluated. The results showed that as rake angle increased, cutting forces, torn grain, waviness, and roughness decreased. The lowest cutting forces and the best surface quality were obtained with 65 of rake angle. At this angle, cutting forces and surface quality were more affected by depth of cut than by cutting direction variations. Thus, as depth of cut decreased, the effects of cutting orientation on the cutting forces and surface quality decreased. The application of these results to the canting work of a chipper-canter is analyzed. © 2013 Springer-Verlag Berlin Heidelberg.

Effects of cutting direction with respect to grain angle, rake angle, and depth of cut on cutting forces and surface quality during machining of balsam fir were evaluated. These factors were analyzed within a perspective of their application to a chipper-canter machining process. Balsam fir is one of the most important boreal species in Canada and is widely used in the pulp and paper industry and construction applications. Wood samples prepared at four cutting directions (0-90°, 15-75°, 30-60°, and 45-45°) were machined using four rake angles (35, 45, 55, and 65°) and three cutting depths (1, 2, and 3 mm). Results showed that rake angle was the most important factor affecting cutting forces and surface quality. Furthermore, as rake angle increased, the effect of cutting direction and depth of cut on cutting forces and surface quality became less important. At 65° rake angle, cutting forces decreased and surface quality increased as depth of cut passed from 3 to 1 mm. Surface quality also improved as cutting action changed from the 0-90° to 45-45° direction. The results gave useful information for improving the performance of the chipper-canter in terms of surface quality and energy consumption. © 2013 by the Society of Wood Science and Technology.

The anatomical properties of seven hybrid poplar clones grown in three sites in southern Quebec, Canada were investigated. Radial and longitudinal variations in selected anatomical properties of wood were measured by image analysis of transverse sections and by fiber quality analysis. Results indicate that all measured anatomical properties varied significantly across sites. Clonal variation was highly significant for all anatomical properties studied, and broad-sense heritability ranged from 0.10 (average vessel lumen area) to 0.76 (cell wall area percentage). Genetic gain was positive for all anatomical properties. The variation in radial pattern was characterized by a rapid increase in the first few years in fiber length, width, and proportion, wall thickness, and percent cell wall area. Ray proportion remained constant, whereas the vessel lumen area and proportion decreased with cambial age.

The effects of the cutting height and cutting width on the surface quality of black spruce cants produced by a chipper-canter were evaluated. Three diameter classes (101.6, 152.4 and 203.2 mm, as measured at the small end diameter of the log) each processed using two cutting widths (12.5 and 25 mm) were studied. The rotation and feed speeds, kept constant at 783 rpm and 197 m/min, yielded a nominal feed per knife (chip length) of 31.5 mm. Twelve logs for each cutting condition were transformed under frozen and unfrozen wood temperatures (winter and summer). The surface quality was analyzed according to roughness and waviness standard parameters. Torn grain was evaluated by means of its maximum depth. The results showed that the surface quality was affected by cutting height, cutting width, and temperature of logs. In general, surface quality was better when processing unfrozen logs at lower cutting width and cutting height. Surface quality varied also within the cant, being generally better at the small end of the log and at the upper part of the cant. The results give useful information to improve the performance of the chipper-canter in terms of surface quality.