Wood and Fiber Science (E-Journal)
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Performance Evaluation of the Least-Cost Lumber Grade-Mix Solver
Get PDFThe least-cost lumber grade-mix problem is of high economic interest to industry. Finding the minimum grade or grade-mix for a given cutting bill can save a company large sums without incurring additional costs. To academia, the least-cost lumber grade-mix problem is of significance due to its complexity and the difficulty to obtain near optimal or optimal results.An earlier study used a new statistical approach to solving the least-cost lumber grade-mix problem. A five-factor mixture design was used to create a lumber grade-mix response surface, on which the minimum cost point is determined. However, this model's merit has never been assessed so far. This study compares the performance of the new statistical model with solutions derived from the widely used OPTIGRAMI 2.0 least-cost lumber grade-mix program.Results revealed that the statistical optimization approach provides better overall solutions for both raw material and total production cost scenarios. For 9 of 10 cutting bills tested, the statistical model found lower-cost solutions compared with those provided by OPTIGRAMI 2.0. The maximum savings found was 105/m3 when processing costs were included (cost savings of 10%). Thus, the new model has the potential to help wood products manufacturers decrease their material and processing costs. This model has been incorporated into ROMI, the USDA Forest Service's rough-mill simulation tool
Investigation of OSB Thickness-Swell Based on a 3d Density Distribution. Part I. The Finite Element Model
Get PDFA finite element model was developed for predicting thickness-swell of oriented strandboard. The model accounts for both vertical and horizontal density variations of the board, or the three-dimensional density distribution. Density variation, resulting from manufacturing processes such as strand orientation and pressing cycles, affects the uniformity of thickness-swell in OSB. The model uses nonlinear constitutive behavior in the through-the-thickness direction. Moisture changes were modeled using transient moisture transfer equations and coupled moisture-density-stress-strain relations. The model was used to predict thickness-swell during a 24-h soak test. The model was able to predict average thicknes-swell of commercial panels with an acceptable error, generally less than 10%
Preharvest Veneer Quality Evaluation of Douglas-fir Stands Using Time-of-Flight Acoustic Technique
Get PDFAcoustic technology has been successfully used as a nondestructive technique for assessing mechanical properties of various wood products and species as well as in tree selection and breeding based on stiffness. In an ongoing endeavor to optimize merchandizing and enhance timber value recovery, seven second-growth Douglas-fir stands of similar age classes in western Oregon were sampled, totaling 1400 trees and more than 3000 logs. The objectives of this research were to 1) investigate the spatial variability of time-of-flight (TOF) acoustic velocities in standing Douglas-fir trees; 2) develop relationships between average Director ST300® (ST300) TOF acoustic velocities of standing Douglas-fir trees and actual veneer produced; and 3) determine the influence of diameter at breast height (DBH) on TOF sound speeds. Spatial location of the stands in terms of their latitude, longitude, or altitude had no predictive capability regarding their veneer quality. Standing tree TOF acoustic velocity and the actual G1/G2 veneer produced using a stress-wave grade sorter had no significant correlation. Significant differences were found among the three different ST300 tools used along the duration of the study as well as between the two opposite side measurements within trees. DBH correlated poorly with both acoustic velocity and G1/G2 veneer recovery
Validation of the Standardized and Simplified Cutting Bill
Get PDFThis research validated the framework for the standardized and simplified cutting bill presented in an earlier paper. The cutting bill validation was carried out in two ways. First, all 20 of the cutting bill's part groups were examined to determine if significant yield influences resulted from changing specific part sizes within the boundaries of a given part group. Second, five cutting bills from industrial operations were fit into the framework of the cutting bill, and the simulated yields from these industrial cutting bills were compared with the fitted cutting bills. Yield differences between the two were calculated and tested for significance. Tests revealed that the standardized and simplified cutting bill framework performed as designed. The maximum yield difference observed was 2% and the average less than 1%. Clustering the industrial cutting bill part requirements according to the cutting bill framework led to an average absolute yield deviation between the original cutting bills and the clustered cutting bills of 3.25%. These results show while cutting bill part-size requirements can be clustered into part groups, yield differences of a certain magnitude are introduced by so doing
Effect of Wood Species on Water Sorption and Durability of Wood-Plastic Composites
Get PDFWood-plastic composites (WPCs) were made from isotactic polypropylene and 10 wood species (8 hardwoods and 2 softwoods). Water sorption and durability of the composites were evaluated. WPCs made with eastern redcedar and Osage orange had low moisture sorption characteristics, lower levels of fungal decay, and increased resistance to mold compared with composites made from other species. The color of the composites was initially quite different, reflecting the differences in color of the various wood species, but after outdoor exposure, the samples were similar in appearance. Metals in contact with WPCs corroded during accelerated exposure and the corrosion of galvanized steel was greatest when in contact with WPCs made from southern pine and black walnut. WPCs made from hickory, sweet gum, black cherry, and red oak corroded ordinary steel more than composites containing other species. These results demonstrate that the inherent characteristics of the wood filler can affect the properties of WPCs. The use of durable wood species in WPCs could result in products with improved durability performance
Effects of Hot-Water Treatment of Black Spruce and Trembling Aspen Bark RAW Material on the Physical and Mechanical Properties of Bark Particleboard
Get PDFThe understanding of the interaction between bark extractives and adhesives is fundamental in the manufacture of bark particleboard for optimum adhesive curing, and mechanical and physical properties of the boards. The effect of hot-water treatment on black spruce and trembling aspen bark was investigated to highlight its impact on the bark particles/phenol-formaldehyde adhesive system, and on the physical and mechanical properties of bark particleboard made from hot-water-treated bark of both species. Bark was soaked in hot water maintained at 100°C for 3 h. The results showed that the hot-water treatment affects the physical and chemical properties of the bark by decreasing hydrophilic characteristics, acidity, and the amount of condensable polyphenols that can react with formaldehyde. The mechanical properties, including static bending and internal bond of particleboard made from untreated black spruce and trembling aspen bark, were higher than those of boards made from hot-water-treated bark of the same species. The thickness swelling of particleboard made from hot-water-treated black spruce and trembling aspen bark was higher than that made from untreated bark. One exception occurred for particleboard made from 100% trembling aspen bark for which no significant difference was found between particleboards made from treated and untreated barks
Evaluation of Three Surfacing Methods on Paper Birch Wood in Relation to Water- and Solvent-Borne Coating Performance
Get PDFHelical planing, face milling, and sanding were used to surface paper birch wood prior to application of coatings. The surface roughness and wetting properties of the wood were evaluated as well as the pull-off strength of water- and solvent-borne coatings, before and after aging. The specimens surfaced with helical planing produced surfaces with the highest surface roughness, the best wetting properties, no subsurface damage, and good pull-off strength before aging. Those surfaced with face milling generated surfaces with intermediate surface roughness, lowest wetting properties, slight surface and subsurface damage, and good pull-off strength before aging. The sanded samples produced the lowest surface roughness, intermediate wetting properties, the highest surface and subsurface damage, and good pull-off strength before aging. After aging, all samples coated with the same varnish exhibited the same pull-off strength regardless of the surfacing treatment. However, loss in pull-off strength after aging was lower for helical planing than for the others. This suggests that helical planing could produce more suitable surfaces for indoor furniture applications. Finally, the water-borne coating created stronger bonds with the substrate than the solvent-borne coating
Impact of Mountain Pine Beetle-Attacked Lodgepole Pine Logs on Plywood Manufacturing
Get PDFIn this work, the possibility of increasing value recovery from mountain pine beetle (MPB)-attacked lodgepole pine (Pinus contorta Dougl.) logs was further investigated, including veneer grading, gluing, panel lay-up, and hot-pressing. This was a follow-up to an earlier study that demonstrated that, by segregating MPB logs, the value recovery could be improved through narrower veneer clipping width, more accurate moisture sorting, and greater drying productivity. Based on pilot plant tests, compared with control veneer of spruce—lodgepole pine—alpine fir (SPF), MPB veneer had various degrees of bluestain, and was significantly denser and stiffer. To minimize manufacturing costs for MPB plywood, glue spread can be kept at the same level as currently used by control SPF plywood. However, the pressing time of 5-ply MPB plywood should be lengthened by about 10% compared with that used by the 5-ply control SPF counterpart. The assembly time should be maintained within 10 to 15 min, keeping veneer temperature as low as possible. Furthermore, the parallel-ply MOE and MOR of 5-ply MPB plywood were approximately 15 and 20% higher than those of 5-ply control SPF plywood, respectively. As a result, MPB veneer was more suitable for making specialty plywood products requiring high stiffness and strength. If manufacturing parameters are properly adjusted in grading, gluing, and hot-pressing, segregating MPB logs from the normal SPF mix also provides an opportunity to manufacture high stiffness plywood with superior dry- and wet-gluebond performance. This could further offset, to a large degree, the reduction in material recovery and the loss in market share for some appearance-based plywood products
Effect Of Processing Parameters, Resin, and wax Loading On Water Vapor Sorption of Wood Strands
Get PDFThe outdoor use of oriented strandboard (OSB) is undesirable if exposed to atmospheric vapor or rain; however, increasing resin and wax content can mitigate adverse sorption behavior of panels under such negative conditions. The objective of this study was to investigate the effect of resin loading, emulsion wax loading, and pressing parameters on the water vapor sorption behavior of loblolly pine strands. Pure earlywood of loblolly pine (Pinus taeda) strands were cut and oven-dried at 50°C. The phenol-formaldehyde resin or wax was sprayed on the wood strands, which were oven-dried at 50°C for 900 s. All specimens were equilibrated at 11% relative humidity (RH) over a saturated salt solution. After equilibration, specimens were placed in a conditioning chamber with the RH increasing from 11-80%. The mass change was continuously recorded by a dynamic contact angle analyzer. The results show that platen temperature, wax loading, compression ratio, and resin loading were influential, in decreasing order, on sorption behavior