Forest companies across Canada are interested in using laser scanners for scaling logs because it has potential for reducing scaling costs. Scanning logs over bark requires a method to obtain the under-bark diameter in order to calculate the solid wood volume. This report evaluates the methods of applying a bark factor to determine under-bark diameter. It also identifies new scanner scaling technologies for measuring bark thickness.
Oriented strandboard (OSB) manufacturing technology has been advancing steadily during the past few years. Today, the industry can produce higher quality OSB at lower costs than ever before in the product's history. Research results have shown that drying costs can be reduced and strand quality can be improved through proper wood yard management, and that the production efficiency can be improved through various ways of optimizing the pressing and processing operations. OSB quality has been improved and board density has been reduced by using long and thin strands in panel face layers and relatively short and thick strands in the panel core. The press times have been reduced by using higher press temperatures and higher mat face-layer moisture contents. The degree of strand alignment has been improved by controlling the falling distance from the alignment heads to the top of mat being formed. Strands alignment has been further enhanced by arranging the alignment disc gaps in such a way so that narrower strands can be aligned through narrower gaps and directed towards core while wider strands can be aligned through wider gaps and directed towards the panel surfaces. Based on these technical advancements, OSB can be produced faster and at a lower density without sacrificing quality. Consequently, the OSB industry is in the position to improve panel quality without resorting to costly options such as increasing resin content and press time.
Structural design catalogues enable road builders and field personnel to optimize aggregate thickness based on field conditions, thereby reducing overall road construction costs, increasing road performance, and reducing maintenance costs. Catalogue users can select a design suitable for a given level of road performance and traffic as well as for various subgrade and aggregate properties.
A new laser-based system was successfully developed in the pilot plant for veneer thickness and roughness measurements. This system was tested for both green and dry spruce veneer. The comparisons were made between the green veneer measurement and dry veneer measurement, and between the laser-based system measurement and actual digital measurement. A linear mixed effect model was used to estimate the within-sheet and between-sheet variations of veneer thickness and roughness and their causes.
A good correlation was found between the laser-measured thickness and caliper-measured thickness. The laser-measured average roughness could also capture the trend of veneer surface roughness determined by the visual classification. Thus, the new laser-based system can be a useful tool for measuring both veneer thickness and roughness.
For veneer thickness, the within-sheet variation seemed to be larger than the between-sheet variation, and the laser-based measure had a larger variation than the digital-based measure for both green and dry veneer sheets. With the green veneer, higher veneer moisture content and density would lead to a larger difference between the two measurements. The laser-based method tended to classify more "thick" sheets than the digital-based method, but this tendency was not obvious with the dry veneer. Such tendency also became negligible by factoring in either veneer moisture content or density. Thus, in the real applications, the accuracy of the new laser system can be improved for measuring green veneer thickness with a calibration of moisture content and/or density.
For veneer roughness, the within-sheet variation was again larger than the between-sheet variation, and the dry veneer had a larger variation than the green veneer. Further, the tight side variation was generally larger than the loose side variation. The above information is deemed useful for establishing an overall veneer quality criterion for industrial applications. Further work is scheduled to adopt the new laser-based system for real-time measurement of green veneer thickness and roughness.
The bending properties of aspen waferboard can be improved by increasing the resin content and/or board density. These options, however have limited effect and are very costly. On the other hand, panels produced with longer, oriented stands have demonstrated significant improvements in bending strength and stiffness. The panel industry has recently used wafers or strands up to approximately 102mm (4in), however, the utilization of much longer material is practical. In addition to more efficient use of the wood resource, structural panels with improved properties can penetrate more demanding applications, particularly as future engineering materials, and overcome some problems experienced with traditional wood composites such as creep. The overall objective of the study was to demonstrate that by using long strands, coupled with appropriate strand alignment, strand thickness, and face-to-core layer ratio, a structural panel can be produced with superior strength and stiffness in the aligned direction while maintaining adequate properties in the cross direction. The specific objective for this year's work was to establish the improved performance using panels produced in structural sizes and under conditions that parallel those of the industry more closely. Manufacturers of oriented strandboard and waferboard can use the information to produce high performance OSB panel products with minimal effects on production parameters and costs.
FERIC conducted a field study to determine the optimum aggregate thickness for roads traveled primarily by trucks equipped with tire pressure control systems (TPCS). The main objective was to establish if savings during road construction could help justify the cost of TPCS technology. The initial results showed that aggregate thickness could potentially be reduced by more than 28% at the test location. This reduction would result in savings in aggregate costs of at least $4000/km, which could help cover the cost of TPCS.
Basedon a preliminay testing, an optimized procedure for in-panel variability evaluation has been developed. A database was created consisting in fifty-five 0-2 OSB panels from nine member mills of the SBA conforming to the Canadian standards. The panels have been evaluated at the Eastern Laboratory of Forintek Canada Corp. and at the Alberta Research Council. Each panel was spit into 18 squares containing specimens for conducting tests on tensible strength perpendicular to surface (IB), thickness swelling (TS), water aborption (WA), moisture content (MC), density, thickness and static bending (MOR/MOE). Variance was used as the criteria for in -panel variability.
A survey with experts from the industry and research centres estimated that the variability on thickness, MOR/MOE parallel to forming, TS and IB is the most critical for the applications of OSB. According to the tests results, the most variable properties were MOE (variance from 405 to 676 GPa), MOR (variances from 28 to 38 MPa) parallel to forming and IB (variances from 5 to 11 kPa). The in-panel variability was on average ten times higher compared to among-panel variability, and the in product vatiability was three times as high as the among product variability. Density variation significantly affected only the variations in MC, WA, MOR and MOE. Density at break point and panel core density did not show better correlation correspondingly with MOR and MOE compared to average density. Further research is suggested to grade the factors of variability in OSB panels by their importance, to determine the criteria for acceptable limits of property variations and to define methods for on-line monitoring of horizontal density distribution.