Samples of end-matched preservative-treated dimensional lumber have been exposed in ground contact for 10 years at Forintek's two test plots in Ontario. At Kincardine, the site supports a colony of the Eastern subterranean termite, Reticulitermes flavipes (Kollar); at Petawawa, there is no termite activity. While decay is somewhat more pronounced at Kincardine, the major difference between the sites is due to the presence or absence of termite activity. Termites are a much more serious threat than decay for treated wood with shallow preservative penetration.
During the last decades, Engineered Wood Flooring and Laminated Flooring experienced dramatic increase in demand from consumers in Europe and Asia, and those two products have taken large market share to the traditional hardwood strip flooring and to other floor covering material like textile, vinyl, etc. In North America, these new multi-layer parquets are just taking off, in 1997, Engineered Wood Flooring share of hardwood flooring was 34% and growing fast. This compares with a market share of 67% in Europe. There appears to be much room for growth in North America. The rapid increase of hardwood flooring products in the world in recent years associated with the decrease of available hardwood raw material made the multi-layer and laminated flooring products interesting alternatives for the hardwood flooring industry. Canada is an important supplier of the hardwood raw material for the European production of both hardwood and EW Floorings. Since some volumes of EWF production from Europe are exported to North America, we do not see any reason why they should not be manufactured in Canada with a competitive advantage. The window of opportunity is there to be exploited.
High Pressure Laminate flooring, a composite product made of High Density Fiberboard (HDF) overlaid by coated paper and presenting a very high-resistance surface finish, is also growing very fast in the U.S. The focus was less on this product in this report since contrarily to EWF, HPL flooring is already being produced in Canada. Also a high capacity for manufacturing this product is currently being built in S-E Asia and in China and we know these countries are low-cost producers, very hard to compete with.
Standards and methods for testing such products were reviewed. It was observed that the European market is very much standard driven, German standards leading the way in that respect. North American are more driven by "lifetime limited warranties”, although some voluntary standards have been defined by the industry. In any case, all testing methods that were observed in these standards can be performed in Forintek materials testing laboratories.
The main problems associated with such products are certainly their negative reaction to variation of moisture content. In this report, methods for predicting those reactions were elaborated in terms of quality of construction and performance. More specifically, testing methods were defined, tried and found to be effective to test surface planeity, gap formation associated with shrinkage and cupping. A process quality control method was also proposed to help eventual producers to control their gluing process. Certainly more research needs to be done to find the best parameters in terms of products and methods of production to develop high quality products that consumers will like to use in their home. Additional research is also required in order to find which backing and core materials could provide the future Canadian EWF industry a sustainable competitive advantage.
Given the remarkable growth of engineered wood products (EWP) in recent years, and considering industry’s desire to maximise product recovery and value, Forintek undertook a literature search and mill visits to investigate drying practices in Eastern Canada regarding major engineered products (MSR lumber, finger-jointed studs, wood I-joists, glued-laminated beams), and how such practices affect manufacturing processes.
The study revealed that most plants were equipped with on-line moisture detectors to reject undesirable pieces, but, with a few exceptions, little effort was made to adapt drying specifications to EWP requirements. The lumber used was generally dried to the same standards as commodity lumber (19 per cent maximum) even though high moisture contents caused pieces to be downgraded by MSR machines, and moisture content differentials between adjoining pieces was thought to be responsible for some poor finger-joints in structural studs. Based on the experience of some mills, questions were raised as to the effect of high-temperature drying on mechanical properties.
However, attitudes were observed to be changing to a client focus as operations became better established, especially in integrated plants. Recommendations made to support improved returns through drying quality include investigation of 1) the effect of moisture content differentials on finger-joints, 2) optimum moisture contents and drying schedules for MSR production, and 3) the effect of high-temperature drying on I-beam flange material performance.
L'industrie du sciage est une composante majeure de l'économie canadienne. Avec les coûts croissants d'approvisionnement et la qualité décroissante de la matière première, cette industrie doit améliorer son procédé actuel ou chercher de nouvelles façons de récupérer davantage de chaque arbre. Étant donné que les opérations effectuées lors du procédé de sciage impliquent des décisions comportant plusieurs paramètres, l'utilisation de l'ordinateur s'avère de plus en plus avantageux.
Dans le cadre de ce projet, des modèles ont été développés afin de simuler le sciage selon la courbure. Cette technique, de plus en plus répandue, permet de récupérer davantage de sciages de meilleure qualité. Avec la panoplie d'équipement de sciage courbe ayant chacun ses particularités, il devient difficile de savoir quelle technologie sera la mieux adaptée à nos besoins. L'utilisation de la simulation permettra de mieux comprendre cette technologie et de bénéficier de son plein potentiel.
Log bucking is one of the most important operations in the transformation of trees into lumber. A bad decision at this stage can jeopardize the optimal recovery in volume or in value. The problem of optimizing the recovery during the bucking process has been solved using, among others, the dynamic programming approach. By introducing certain assumptions into the dynamic programming algorithm formulation this approach becomes both more realistic and more efficient. The algorithm defined here is used in an integrated bucking-breakdown model. Example simulations demonstrate the computational speed improvements that result from the introduction of the assumptions.
A literature review was made of publications on veneer drying. A discussion on the three types of air-circulation dryers, longitudinal, cross-flow and jet dryers is presented as well as other drying methods including platen, steam-press, radiofrequency (RF) and RF/vacuum drying. Good temperature control in veneer dryers such as in jet dryers using high temperatures in the green end and lower temperatures in the dry end will result in higher quality veneer with less surface inactivation. By maintaining a high humidity in veneer dryers, the following benefits result: faster drying rates, lower energy costs, less chance of surface inactivation and less chance of dryer fires. The following veneer drying benefits result by incising veneer on the lathe: faster drying rates and flatter veneer for easier handling on automated lay-up lines. Other important benefits include: fewer spin-outs at the lathe, less curl-up for the veneer near the core, especially spruce, higher veneer yields, reduced "blows" in plywood during pressing and improved preservative treatability of plywood. A drying strategy involving drying incised veneer to a uniform high moisture content and pressing this face incised veneer (15% m.c.) with dry core incised veneer (3% m.c.) using a moisture tolerant phenolic adhesive, could allow up to 30% reduction in pressing time.
Published literature on joining of panel products into larger sized sheets was collected and evaluated. Current technology can produce acceptable bending strengths and stiffness for oversized panels. This technology is at present commercially available in Canada. There is a small current market in Canada for these types of products which is being met by imports.
Warp and twist can be defined as any deformation of panel shape from a flat plane and frequently results from exposure to moisture or humid conditions. Warpage and twist is generally considered to be less of a problem for composite panels than for solid wood products since any movement in one layer tends to be counterbalanced by that of other layers. However increased consumer demand for specific panel thickness and face species and the need for panel manufacturers to control costs has resulted in some panel products giving less than optimum performance. While many research papers on composite panels discuss warp and twist few have featured these as the main objective. This study has attempted to review the current level of knowledge in published literature. The consensus opinion in the published material is that for a panel to resist warp and twist, the construction must be balanced in species, density, grain orientation, layer thickness and moisture level.
This report covers three days of testing on the primary breakdown line at the Pope and Talbot sawmill in Spearfish, South Dakota. Significant increases in production were achieved by using variable speed drives on the feed system and quadruple bandmills. By selecting rim speeds that provide the better cutting accuracies, this increase can be obtained with little or no increase in sawing deviation. In addition variable pitch sawblades alleviated washboard problems at all rim speeds tested and showed a small improvement in cutting accuracy. There appeared to be some alignment problems with the quad that were temporarily overcome by shimming the guides.
This project was initiated to provide technical assistance to the Alberta wood drying industry. The specific objective was to identify opportunities to improve product quality through modification of the drying schedules. Seven mills representing almost 50% of the solid, softwood lumber production in the province were selected for the project. All mills provided a great deal of cooperation and commitment to the project was excellent. In general, lumber drying operations in Alberta are in good physical condition and operating personnel have a sound knowledge of basic drying concepts.
In general, drying schedules were found to be quite harsh. the specific concerns at most mills related to too rapid a heat-up rate and extremely low relative humidity at the end of the drying cycle. Most of the schedule modification called for more gradual and controlled heat-up rates with higher wet-bulb temperatures. The objective of this modification is to avoid setting up conditions othat promote variability in moisture content from board to board. Higher relative humidity is required at the end of the drying cycle to avoid over-drying faster drying boards. Achieving a reduction in final moisture content variability and a higher overall average moisture content should be the objective of drying schedule modifications.
Mill visits were used not only to review drying schedules but also to conduct a brief inspection of drying practices and equipment. It would be unproductive to identify schedule modifications if there were obvious shortcomings in other areas of the operation that would make it difficult to implement or over-shadow the effect. The primary concern with drying equipment is the leakiness of the structures. A common recommendation to mills was to tighten up kiln doors and walls in order to retain more moisture in the kiln environment. Another area of concern was related to lumber handling operations. Most problems in this area could be addressed through educating and training staff working at stackers, handling material in the yard, or preparing loads for the kiln.
Logging and log storage practices at all of the mills visited has a serious and detrimental impact on the drying operations. At most times of the year, operators are having to deal with a wood supply that has a mix of initial moisture content conditions. Most mills seem to manage the small percentage of balsam fir in their mix effectively. Some future gains may be achieved through refined presorting techniques that take into account initial MC variability as well as differing drying characteristics between species.