Thirty full-length sample trees from the B.C. Interior were selected for a study to determine whether external log characteristics can predict internal log quality. The sample trees were also used to create 3-dimensional log images for sawmill simulation purposes. "LogSaw", a simulation tool with internal log defect detection capabilities, was used to explore the extent to which internal and external log quality information can improve log breakdown optimization. A model of a hypothetical sawmill producing lumber for the standard North American dimension market was created to study how lumber value recovery depends on different sawing optimization scenarios.
Three sawing optimization scenarios using different levels of knowledge of internal log defects were compared to currently used sawing optimization technique:
Ideal sawing optimization - all defects within log interior are known.
Sawing optimization using only the knowledge of surface knots.
Sawing optimization using log rotation instructions based on zones of least external knot density.
Simulation results have shown that it is worthwhile to “look into the log”. When compared with the current optimization technique, the sawing optimization, including the full knowledge of log interior, has increased the value recovery by 6.2%. When only the surface knots were projected into the log interior and included in the optimization, the value recovery had increased by 4.3%. Even this 4.3% increase is still a big improvement because this sawing optimization could be implemented using currently available scanning technologies and optimization software enhanced to include log surface knots. The scenario of using log rotation instructions based on predicted zones of least internal knot density did not show value recovery improvement.
Including surface knots in the log breakdown optimization has considerably increased sawmill revenue; the hypothetical sawmill considered in this study, processing 400,000 m3 of log per year, has increased its revenue by $2.2 million.
Manufacturing analysis using computer flow simulation has been applied successfully in pilot projects to several Alberta value-added wood products companies in the sectors of re-manufacturing and furniture manufacturing. This project continues these pilot projects examining the application and potential benefit in manufactured/prefab homes. An Alberta manufactured/prefab home manufacturer was selected for this project. The wall-line was chosen for this study. The study was accomplished through detailed observations and data collection, which identified several bottlenecks that included the framing table, squaring table and the linear configuration of the line. From observations, the squaring table was labour intensive and the material handling equipment was quite slow. At the framing table, the stud grade being used contained many twisted and bowed boards, which required additional time to align and fasten the studs. Lastly, the single-line configuration created bottlenecks during the transition from sheathed and unsheathed products. From observations and discussions with staff, potential improvement scenarios were developed. Simulation models were developed for each of these scenarios to evaluate their effectiveness and return on investment. The scenarios examined were: affect of panel sheathing ratio, improving efficiency at the squaring table, improving efficiency at the framing table, addition of a branch-line for unsheathed products and the addition of the branch-line in combination with increased efficiency at the framing table. The implementation of pre-cut OSB panels was simulated to reduce processing times at the squaring table by 30%, which increases throughput by 15%. The addition of a branch-line for unsheathed products showed a potential production increase of 10.8%. However, the simulation models also showed that the framing table could not maintain a consistent supply to the squaring table. The use of a higher stud grade was modelled showing a potential production improvement of 17.5%. As a result, the potential benefits in this particular wood products business demonstrates that computer flow simulations can be applied to Manufactured/Prefab Home manufacturers and may potentially have further implications in other similar Alberta value-added industries.
The objective of this project was to quantify the lumber value recovery up-lift that is achievable by adding surface defect detection to board profile scanning in sawmill edger optimization. Optimized profile edging solutions of 194 spruce-pine-fir sample boards were compared to optimized edging solutions that took into account surface defects as well as the geometric shape of the board. The edger optimization improvement was found to be marginal. Data analysis showed a benefit of only $0.13 per m3 of processed logs, an equivalent of $237.11 per shift. The findings of this report are mill specific. The value recovery figures were collected in a mill with given log supply, machinery and market orientation. A more significant up-lift in value recovery would likely be obtained for higher valued products produced from larger logs typically processed in coastal sawmills.
Le tronçonnage demeure pour la majorité des scieurs de bois feuillus un domaine problématique possédant un potentiel d’amélioration significatif, tant au niveau du volume sciable que du rendement valeur de la ressource disponible. La récupération de la valeur optimale d’une tige est directement liée à l’efficacité du préposé au tronçonnage. De mauvaises décisions de sa part résultent en une perte de valeur. Les principales raisons entraînant de mauvaises décisions sont la complexité et l’imprécision des lignes directrices, le grand nombre de classe de qualité, les exigences de productivité, le manque de formation et d’outils d’aide à la prise de décision. De plus, le nombre possible de combinaisons de longueur de billes et de découpes pour une même tige est assez important. L’évaluation d’une partie seulement des solutions potentielles requiert déjà un effort mental important.
Un système de tronçonnage complètement optimisé demeurera probablement une solution inaccessible pour la majorité des industriels à moyen terme. Cependant, la technologie des lecteurs et des caméras progressant très rapidement, il existe une possibilité de développer un système hybride qui pourrait générer des bénéfices importants. La ressource disponible est bien souvent de piètre qualité et il est envisageable de maximiser le volume de fibre sciable en optimisant le tronçonnage selon la courbure et la géométrie des tiges. Ce projet vise à chiffrer les bénéfices potentiels de cette approche de tronçonnage et d’en valider la faisabilité économique.
This project presents the results of a computer simulation of the recovery obtained from six bucking optimization systems equipped with different scanner and conveyor combinations.
Forty sample stems were scanned and stem models developed to provide input for Forintek’s sawing simulation program, OPTITEK®. Input files of both sawmill machinery and their products were developed based upon the operation of a typical sawmill in the Interior of B.C. Optimized bucking solutions were generated, and sample stems were sawn accordingly. Lumber value and volume recovery data were obtained and enabled a performance evaluation of the six bucking optimization systems.
In this project the affect of both the log conveying system and the type of scanner was considered. Both lineal and transverse conveyor systems were studied and the effects of true shape, partial true shape and XY scanners were modelled. Various combinations of parameters were studied and the annual dollar production for such combinations were computed.
Recommendations are made relating to the different systems studied and how the results may be of benefit to mill optimization.