"La durée et les conditions de stockage des bois ronds durant
l’été ont des conséquences négatives sur la qualité, le rendement et les propriétés du bois. La perte en eau, l’apparition de fentes, de coloration et de carie ne sont que quelques-uns des problèmes pouvant survenir."
A multi-agency trial was established to determine the impacts of commercial thinning on the growth, yield, and development of white spruce stands. The commercial thinning operation was completed using a Timberjack 1270 harvester and a Timberjack 1210B forwarder. The Forest Engineering Research Institute of Canada (FERIC) monitored the harvesting phase, determined the operational cost and productivity of the harvester and forwarder, determined the residual tree damage, and evaluated the effectiveness of a brushing crew in increasing the productivity of the harvester in areas with high densities of non-merchantable trees.
In November and December 1994, FERIC compared the lumber yield from two roughly 75-m3 furnishes of softwood harvested with two different systems. One furnish was harvested as full-trees using a feller-buncher, a cable skidder, and a stroke delimber. The other was harvested using a cut-to-length system comprising a single-grip harvester and forwarder. All the wood was scaled and milled separately at Domtar Inc.'s sawmill in Val d'Or, in Quebec's Abitibi region. The results were similar for both furnishes, though the cut-to-length system provided a slight benefit in terms of volume yields and the value recovery per cubic metre. Conversely, the average value of the products produced from full-trees was slightly higher. Losses after drying were nearly identical. However, the operational context may not have been perfectly typical, especially in the case of the full-tree system. Other studies would be necessary to confirm the wider applicability of the results in this report.
To develop a method for establishing a fibre budget in a sawmill, we selected a sample of stems and had it converted into lumber. We also took advantage of this opportunity to pursue this exercise somewhat further by quantifying volume and value recoveries for the sample, as well as the various performance indicators used to monitor the lumber manufacturing process.
A specialized company measured and weighed the stem sample to determine mass/volume ratios. The stems were then bucked and debarked, and we recovered all resulting products and by-products to measure and weigh them, and develop the different bucking ratios. The debarked logs were sawn in a mill and, as for bucking, all resulting products and by-products were quantified, weighed and classified. We used all product and by-product volumes or weights to generate the various indicators used to monitor operations and process performance.
With products and by-products suitably quantified, we introduced product values, which allowed us to determine the value of all products and by-products generated from the conversion of a given log or stem sample. In addition to making it easier to control production value, these performance indicators can be used to compare values generated from similar samples with modified production criteria, or different samples processed through the same production criteria. The ultimate objective is to measure the effects of changes in the resource or the sawmilling process.
To produce in 1993 a conversion factors publication which will help the forest products industry and government agencies in eastern Canada improve the usefulness and comparability of wood consumption and forest product yield information, by reducing errors and inaccuracies caused by frequent misinterpretation of units and inappropriate conversions.
This volume is a useful reference tool which covers conversion factors for the Western industry. Topics include log volume, wood density, bark, sawmilling, veneer and plywood, boards, pulp, shingles and shakes and energy. In many cases the factors presented are average values or rough estimates, but often this level of accuracy is sufficient for mill calculation purposes.
Four-foot hard maple bolts, ranging in diameter from 6 to 16 inches, were produced from pulp wood and sawlogs. The bolts were live-sawn into 1-inch boards to identify the coordinates of each board defect in order to mathematically reconstruct each bolt for simulated sawing. The optimum bolt values were obtained by "computer sawing" the bolt models several times into dimension stock, squares or pallet stock using three sawing patterns; live, around and cant sawing. In the simulated sawing of the actual and theoretical bolts, live sawing consistently resulted in the highest product value. The only exception was for bolts containing a large amount of discoloured wood. In these cases, around and cant sawing performed better than live sawing. In general, liver sawing produced the highest product value for the following reasons; the production of wider boards allows a greater resawing flexibility, fewer saw cuts with less kerf loss and the production of fewer slabs. In-plant studies were conducted to determine the effect of the sawing pattern on productivity. Live sawing increased productivity by 18% for small diameter bolts and up to 30% for larger diameter bolts over the other sawing patterns. While multi-pass systerms may be suitable for the larger, higher quality bolts, it is doubtful that such a system would be viable processing small diameter material down to 6 inches. In processing smaller diameter bolts, it is necessary to have a single-pass system with high productivity to offset the lower quality and value of this material.
L’objectif du projet visait à déterminer la fréquence des bris et des dommages sur les tiges de Pin gris lors de la récolte par arbres entiers et à en quantifier l’impact sur le rendement en volume et en valeur des produits. Les travaux ont été réalisés chez Produits Forestiers Domtar Inc. à Chapleau, en Ontario en novembre 2001.
Deux échantillons de tiges de Pin gris ont été prélevés, le premier contenait 100 tiges représentant les tiges non endommagées et un deuxième échantillon de 121 tiges pour représenter les tiges brisées ou avec des dommages mécaniques. Le matériel échantillon a été mesuré et tronçonné dans la cour de la scierie. Tous les produits tronçonnés ont été mesurés et identifiés avant d’être transformés dans la scierie. Les sciages produits ont été transportés au laboratoire de Forintek à Sainte-Foy pour être séchés et classés.
Les résultats des diverses évaluations montrent que 18% des tiges récoltées sont soit brisées ou endommagées et que plus de 75% des bris se retrouvent dans le haut des tiges. Pour une scierie ayant un approvisionnement de 400 000 m³, les sections manquantes de tiges privent la scierie d’environ 90 000 billes de sciage annuellement. Ces billes possédaient le potentiel pour générer 765 Mpmp et 1 400 Tma de copeaux. Ces pertes représentent plus de 363 000$ annuellement ou 3,96$/Mpmp.
Dans la population de billes tronçonnées on retrouve un autre 3,87% de billes qui ont été endommagées lors de la récolte. L’éboutage additionnel requis pour éliminer ces dommages génère des pertes additionnelles de 0,09 $/Mpmp.
Les fentes après séchage sont aussi plus fréquentes dans les sciages provenant des tiges brisées que des tiges non-brisées. La perte en volume est négligeable alors que la perte en qualité ne représente que 0,02 $/Mpmp.
Au total, les bris et les dommages qui affectent les tiges suite à la récolte selon la méthode par arbres entiers génèrent des pertes de 4,07 $/Mpmp ou 0,94 $/m³ ce qui représente environ 376 000 $ annuellement pour une scierie dont l’approvisionnement est de 400 000 m³.
The objective to this study was to process a matched sample of tree lengths harvested from a mature and an overmature site in order to quantify to lumber volume, lumber quality and lumber value of each tree sample.
