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The effects of wood temperature, cutting width, and knots on the surface quality of black spruce cants processed by a chipper-canter were evaluated. Four matched groups of logs were machined at temperatures of 20°C, 0°C, −10°C, and −20°C. Each log was transformed at two cutting widths (CW: 12.7 and 25.4 mm). Knot characteristics were measured on the cant surfaces after log processing. Surface quality of cants was assessed by roughness and waviness parameters and torn grain. The quality of surfaces was affected by the temperature of logs and cutting width. Poorer surface quality was obtained at larger cutting widths. This was caused by increased cutting forces when processing more material at larger cutting widths, compounded by the presence of knots. Waviness and roughness were higher for frozen logs than for unfrozen logs. Although the sub-zero temperatures caused higher cutting forces and vibrations, their effect was partly offset by the strengthening of the earlywood and the brittle behaviour of frozen wood. Correlations and regression analyses showed that the optimisation of the cutting conditions for decreasing waviness and roughness should also reduce the torn grain depth. Moreover, the position and area of knots could be considered to minimise waviness and roughness and the occurrence of torn grain. [ABSTRACT FROM AUTHOR]

A conventional straight knife cutterhead and three helical knife cutterheads were tested for planing sugar maple wood (Acer saccharum Marsh.). Effects of helix angle and feed per knife (FK) on maximum cutting forces, sound level, and power consumption were evaluated. A 3-axis dynamometer, an array microphone, and a watt transducer were used to simultaneously record the forces, sound level, and power consumption during machining, respectively. Parallel ([F.sub.P]), positive and negative normal ([F.sub.NP] and [F.sub.NN]), lateral ([F.sub.L]), resultant ([F.sub.R]) forces, and sound level increased as FK increased. Helical tools produced lower [F.sub.P], [F.sub.NP], [F.sub.NN], and [F.sub.R]. Parallel forces tended to decrease as helical angle increased. Differences among helical tools were not significant for normal forces. Helical tools produced higher [F.sub.L] at medium (2.9 mm) and high (4.7 mm) feeds per knife. [F.sub.R] decreased as helix angle increased. The impacts of these cutting forces on the appearance of surface defects and ways to reduce them were discussed. Helical cutterheads considerably generated lower sound pressure level, with a maximum difference of up to 8 dB(A). At low FK (1.3 mm), helical tools required slightly lower cutting power. Key words: cutting forces, helical planing, peripheral cutting, sound level, surface quality, power consumption. Une tete de coupe munie d'un couteau droit conventionnel et trois autres munies de couteaux helicoidaux ont ete testees pour le rabotage du bois d'erable a sucre (Acer saccharum Marsh.). Les effets de l'angle d'helice et de l'avance par couteau (FK) sur les efforts de coupe maximums, le niveau sonore et la consommation d'energie ont ete evalues. Un dynamometre a trois composantes, un microphone et un transducteur de puissance ont ete utilises pour enregistrer simultanement les forces, le niveau sonore et la consommation d'energie durant le rabotage. Les forces paralleles ([F.sub.P]), normales positives et negatives ([F.sub.NP] et [F.sub.NN]), laterales ([F.sub.L]), resultantes ([F.sub.R]) ainsi que le niveau sonore augmentaient avec l'augmentation de FK. Les outils helicoidaux produisaient de plus faibles valeurs de [F.sub.P], [F.sub.NP], [F.sub.NN] et [F.sub.R]. Les forces paralleles avaient tendance a diminuer avec l'augmentation de l'angle d'helice. Les differences entre les outils helicoidaux n'etaient pas significatives dans le cas des forces normales. Les outils helicoidaux ont produit une FL plus elevee avec une avance par couteau moyenne (2,9 mm) et rapide (4,7 mm). La valeur de FR diminuait avec l'augmentation de l'angle d'helice. Les impacts de ces efforts de coupe sur l'apparence des defauts de surface et les facons de les reduire sont abordes dans la discussion. Les tetes de coupe helicoidales ont genere des niveaux de pression acoustique considerablement plus faibles, avec une difference maximale de 8 dB(A). Avec une faible valeur de FK (1,3 mm), les outils helicoidaux ont requis legerement moins de puissance. [Traduit par la Redaction] Mots-cles: efforts de coupe, rabotage helicoidal, coupe peripherique, niveau sonore, qualite de surface, consommation d'energie., Introduction Sugar maple (Acer saccharum Marsh.) is a diffuse-porous hardwood and one of the most important tree species in the province of Quebec, in Canada. Maple wood represent 5.2% (in [...]

The effect of the radial force applied by a ring debarker tip to frozen balsam fir (Abies balsamea (L.) Mill.) logs, obtained at three positions on the stem, was studied. A one-armed ring debarker prototype was built, which controlled the radial force, the rake angle, and cutting and feed speeds. Balsam fir logs at -19[degrees]C were debarked at three levels of radial force. The rake angle, tip overlap, tip edge radius, and cutting and feed speeds were kept constant. Debarking quality was evaluated by two criteria: the proportion of bark remaining on log surfaces and the amount of wood fibres in bark residues. Log characteristics (dimensions, eccentricity, bark thickness, and knot features), bark-wood shear strength, and the basic densities of sapwood and bark were also measured. Results showed that the radial force had a significant effect on debarking quality. The proportion of bark remaining on log surfaces increased while the amount of wood fibres in bark residues decreased as radial force decreased. A radial force of 18.5 N*[mm.sup.-1] is suggested for an optimal debarking quality. In contrast, log position on the stem did not affect the debarking quality indicators. Results also showed that the proportion of bark remaining on log surfaces increases as bark-wood shear strength and the proportion of knot surface increase, while the amount of wood fibres in bark residues increases as bark-wood shear strength decreases and logs are more eccentric. The results give useful information to improve the debarking process within the studied range of log diameters and debarking parameters. Key words: ring debarker, radial force, bark-wood shear strength, debarking quality. L'effet de la force radiale appliquee par le couteau d'une ecorceuse a anneau sur des billes gelees de sapin baumier (Abies balsamea (L.) Mill.), a trois positions dans la tige, a ete etudie. Un prototype d'ecorceuse a anneau a un bras a ete construit, permettant de controler la force radiale, l'angle d'attaque ainsi que les vitesses de coupe et d'avance. Des billes a -19[degrees]C ont ete ecorcees a trois niveaux de force radiale. L'angle d'attaque, le chevauchement du couteau, le rayon a l'extremite du couteau, ainsi que les vitesses de coupe et d'avance ont ete maintenus constants. La qualite de l'ecorcage a ete evaluee a l'aide de deux criteres: la proportion d'ecorce qui reste a la surface de la bille et la quantite de bois dans les residus d'ecorces. Les caracteristiques des billes (dimension, excentricite, epaisseur de l'ecorce et caracteristiques des nreuds), l'adhesion bois-ecorce ainsi que les densites basales de l'aubier et de l'ecorce ont aussi ete mesurees. Les resultats montrent que la force radiale a un effet important sur la qualite de l'ecorcage. La proportion d'ecorce qui reste a la surface des billes augmentait tandis que la quantite de bois dans les residus d'ecorces diminuait avec la diminution de la force radiale. Une force radiale de 18,5 N*[mm.sup.-1] est suggeree pourune qualite d'ecorcage optimale. Par contre, la position de la bille sur la tige n'avait pas d'effet sur les indicateurs de qualite de l'ecorcage. Les resultats montrent egalement que la proportion d'ecorce qui reste a la surface des billes augmente avec l'augmentation de l'adhesion bois-ecorce et de la proportion de la surface occupee par les nreuds, alors que la quantite de bois dans les residus d'ecorces augmente avec la diminution de l'adhesion bois-ecorce et l'augmentation de l'excentricite des billes. Les resultats fournissent des informations utiles pour ameliorer le processus d'ecorcage dans les limites des diametres des billes et des parametres d'ecorcage etudies. [Traduit par la Redaction] Mots-cles: ecorcage a anneau, force radiale, adhesion bois-ecorce, qualite de l'ecorcage., Introduction The process of removing bark from the stem is the first step in the manufacturing process of most wood products. Debarking systems and strategies are developed to increase the [...]

The effects of cutting speed (CS) and feed-per-knife (FK) on the surface quality of black spruce (Picea mariana [Mill.] B.S.P.) cants processed by a chipper-canter were evaluated. Nine matched groups of logs were studied at 20, 25, and 30 m/s of CS, and 19, 25, and 32 mm of FK. Each log was processed at frozen and unfrozen conditions. Knots and grain angle measurements were taken on the cant surfaces after machining. The quality of cants was assessed utilizing waviness, roughness, and torn grain. The results showed that the surface quality was affected by CS and FK. Surface quality improved as FK decreased, likely due to decreasing cutting forces. The waviness tended to improve as CS increased, which could be partly due to the reduction of the non-cutting period between knives at higher CS. The waviness and depth of torn grain were similar for frozen and unfrozen logs. Surface quality varied within the cant, being generally poorer in the lower half. Knots and orientation of spiral grain (left-handed) contributed to diminishing the quality of surfaces. Finally, the results of correlations and regression analyses showed that optimizing the cutting conditions to decrease waviness should also reduce the depth of torn grain. [ABSTRACT FROM AUTHOR]

A conventional straight knife cutterhead and three helical knife cutterheads were tested for planing sugar maple (Acer saccharum Marsh.) and black spruce (Picea mariana (Mill.) B.S.P.) woods. The effects of helix angle and feed per knife (FK) on roughness, tactical perception, and anatomical features of the planed surfaces were evaluated. Rk and Rpk parameters were found to be more descriptive in evaluating the roughness of these woods and proved to be good indicators of tactile perception. Roughness increased as the helix angle and feed per knife increased for both wood species. Sugar maple showed smoother surface than black spruce. Surfaces planed with helical knives showed a fuzzy texture resulting from cell-wall fibrillation. For sugar maple wood, the differences in roughness between straight and 40° helical knives were small. Therefore, the latter must be preferred for planing this species. Roughness of planed black spruce also increased as helix angle increased and in this case its effect depended on FK. The straight knife produced the lowest roughness, for all studied FKs. Planing with helical knives produced higher roughness as a result of cell-wall fibrillation. This defect was more pronounced than that of sugar maple, and by far more present with helical knives of 50° and 60°. Therefore, straight knives working at low FK (1.3 mm) should be preferred for planing black spruce wood when roughness is a critical concern. Possible benefits provided by rougher surfaces planed by helical knives are discussed. [ABSTRACT FROM AUTHOR]

The cutting speed (CS) and feed per knife (FK) are among the most important variables affecting chip size produced by chipper-canters. Nine groups of black spruce logs were processed at three CS (20, 25, and 30 m/s) and three FK (19, 25, and 32 mm). Each log was processed under frozen (−13°C) and unfrozen (19°C) conditions. Chip size was assessed by thickness and by width/length. Chip size increased as CS decreased and FK increased. Frozen logs produced thinner chips and higher proportions of small chips. The weighted mean chip thickness (WCT) increased as the FK increased and CS decreased. The highest accepts proportion by thickness was obtained at 19 mm FK and 20 m/s CS, while the highest width/length accepts were produced at 32 mm FK and 20 m/s CS. Grain angle and knot proportion were the most significative covariates for chip size. Regressions showed that FK, CS, knot proportion, grain angle, and taper were the best predictors for WCT, explaining 86% and 81% of the WCT variations for frozen and unfrozen logs, respectively. Therefore, a combined evaluation of cutting parameters and raw material is essential to predict WTC, reduce chip size variations, and thus improve chip quality. [ABSTRACT FROM AUTHOR]

A conventional straight knife cutterhead and three helical knife cutterheads were tested for planing black spruce wood (Picea mariana (Mill.) B.S.P.). Effects of helix angle and feed per knife (FK) on maximum cutting forces and sound level were evaluated. A 3-axis dynamometer and an array microphone were used to simultaneously record the forces and the sound level, respectively. Parallel (FP), lateral (FL), resultant (FR) forces, and sound level increased as FK increased. Helical tools produced lower FP, positive and negative normal forces (FNP and FNN), and FR. Parallel forces tended to decrease as helix angle increased at high FK (4.7 mm). Differences among helical tools were not significant for normal and resultant forces. Cutterheads with the two highest helix angles (50° and 60°) produced higher FL at low (1.3 mm) feed per knife. Impacts of these cutting forces on the production of surface defects and ways to reduce them were discussed. Helical cutterheads considerably generated lower sound pressure level, with a maximum difference of up to 11.5 dB(A). [ABSTRACT FROM AUTHOR]

Four matched groups of 15 black spruce logs were processed with a chipper–canter at temperatures of 20, 0, −10, and −20°C. Each log was transformed at two moisture contents (MCs) (green and air-dried) using two cutting widths (CWs) (12.7 and 25.4 mm). Mean MC for each CW was assessed from a sample of the obtained chips. The results showed that mean power, energy consumption, and specific cutting energy were significantly affected by the temperature and CW, and in a lesser degree by the MC. These parameters were greater when cutting frozen logs. Mean power and energy consumption were higher at the larger CW, as a result of the higher volume of removed wood. However, specific cutting energy increased as CW decreased. This behavior was related to the higher level of fragmentation occurred with the smaller CW. These results are useful to estimate changes in energy requirements occurred within the range of cutting conditions studied here. [ABSTRACT FROM AUTHOR]

Liquid phase sintering (LPS) of powder metallurgy (PM) components is a well-recognised strategy to enhance the densification of pressed-and-sintered compacts. This work reports the investigation on the liquid phase formation when a Fe–Ni–Mn–C–B master alloy (MA) is used as a boron carrier in combination with two iron base powders pre-alloyed with Mo. Through differential scanning calorimetry tests, quantitation of the microstructure with the help of artificial intelligence, as well as measurement of sintered density and strength as a function of sintering temperature, it was possible to unravel the mechanisms that take place before and during LPS. It was confirmed that a cascade of events takes place in the solid state prior to reaching the temperature necessary for a eutectic reaction to form a liquid. Additionally, the pre-alloyed Mo content was identified as a factor that modifies the initiation of LPS but not the LPS mechanisms per se. [ABSTRACT FROM AUTHOR]

The microstructures of powder metallurgy steel components, especially those made from premixes, are known to be complex due to the presence of a diversity of stable and metastable phases, as well as pores. Similarly, this microstructural heterogeneity also characterizes the fracture surface of these specimens, where various fracture modes can be observed. In addition, the presence of certain phases in varying volume fractions, or located in critical areas such as grain boundaries, can act as a preferred path for crack initiation, crack propagation and fracture. In this work, a Deep Learning algorithm was trained and used as a tool to deal with the tedious and complex task of segmenting highly inhomogeneous fractographs, where individual microstructural features are not easily discernable. The quantitative values derived from the segmented fracture surfaces, combined with a quantitative assessment of the microstructure obtained using a second Deep Learning algorithm, allowed us to establish correlations between the proportion of specific phases and variations of mechanical properties, as well as changes in the preponderance of certain modes of failure. [ABSTRACT FROM AUTHOR]