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.
In this project, a comprehensive experiment studied the impact of wax type, wax content, wax heating temperature and wax molecular weight on OSB panel performance. It shows that to allow tall oil, hydrogenated soybean wax, linseed oil, and low density polyethylene (LDPE) to be used for OSB, further work is needed. We need to add wax in the OSB process; otherwise panel dimensional stability will be ruined. There is an optimal wax content of around 1% in OSB production. The wax content in OSB panel did not need to be higher than 1%. With the waxes tested, wax heating temperature should be higher than 90°C. At a fixed wax heating temperature, optimal wax molecular weight is 520 Daltons for OSB application. Applying high molecular weight wax (600 Daltons) on panel surface may help to improve panel bending strength.
The experiment shows that partial substitution of slack wax with LDPE at the OSB panel surface layer may be feasible.
Experimental results also show that using contact angle and surface tension tests may help us to screen waxes for OSB panel application.
Based on the experimental data, one should handle different waxes in different ways. By engineering wax application parameters one can develop a cost effective way to produce composite panels to meet dimensional stability requirement. Further testing on the feasibility of using contact angle and surface tension to differentiate wax should be conducted. Emulsifying low density polyethylene should be further investigated. Further research is also needed to verify how wax operational parameters affect panel strength.
A pilot plant apparatus was built to electrostatically spray phenolic resin on strands. To evaluate the resin distribution on these strands, an image analysis method was developed. The experimental conditions in this study made it difficult to compare electrostatic treatments to control (non- electrostatic) treatments. Although not statistically significant, there were notable differences between these treatments which indicate that electrostatic resin application may improve panel properties and is therefore worth further investigation. First of all, the electrostatic treatment produced panels with a 10% higher internal bond than the control. Secondly, the resin distribution results show that the electrostatic spray, on average, covered a 30% greater area of the strands than the control even though both treatments applied resin at the 2% resin solids level. Further experiments using alternative test procedures are planned to compare electrostatic treatments to control treatments that simulate industrial conditions.
A prototype scanning system successfully demonstrated the capability of real-time, log pocket monitoring that can be used to alert operators of improper pocket filling practice.
Several previous FPInnovations studies have shown that the log pocket filling is often poorly controlled resulting in poor log alignment and/or incomplete filling that adversely affects both flake quality and strander productivity. Until now there have been no systems available to automatically measure the alignment of logs being fed into the strander or measurement of the actual filling of the strander pockets. An automated monitoring system is needed to signal operators when the log pocket is improperly loaded. This feedback can allow operators to maintain proper log filling procedure to maximize flaking quality.
In March 2013 a machine vision scanning system comprised of a camera, 2 line lasers and computer with image analysis software, was tested for two days at the Peace Valley OSB mill (PVOSB) in Fort Saint John, BC. The scanner’s camera and lasers were mounted 13 feet above the center of the log pocket base. Images of pocket filling were acquired and analyzed for pass/fail conditions. Two image groups were selected for analysis, one of full pocket, aligned logs (pass) and the other containing misaligned logs and/or insufficient pocket fill (fail). For all pocket scans, scanner measurements were compared to manual visual classification.
Approximately 50 different pockets were scanned with results and images saved for analysis. For fill height and vertical log alignment measurement, the scanner correctly identified >95% of all the pockets examined. However, log alignment measurement in the horizontal x-y plane did not function as intended due to poor image contrast that could not be resolved during the mill trial. This technique has been shown to work well in previous pilot plant tests (Groves, 2012) which confirms that the underlying measurement fundamentals are sound. It is recommended that only minor lighting adjustments are required for the scanning system to work well in a mill setting.
Implementing this technology in OSB mills should help to reduce the occurrence of poor pocket filling that can adversely affect strand quality. It should be noted that even small improvements to strand quality and productivity can yield significant cost benefits. It is estimated that reducing fines by a modest 1% and improving productivity by 1% can return in excess of $1 million/year based on an average size Canadian OSB mill.
There are six species of poplar native to Canada's forests. One of the most abundant and widely used of the species is the aspen poplar (populus Tremuloides). Aspen has become the most desirable species for the production of oriented strandboard (OSB). Certain sections of Alberta and British Columbia have considerable stands of aspen. The aspen stands also contain varying amounts of balsam poplar (populus balsamifera) and black cottonwood (populus trichocarpa) and various hybrids of the three species. Forintek Canada Corp's Technical Advisory Committee (TAC) was asked by the B.C.Ministry of Forests to establish whether cottonwood could be a suitable furnish for the production of OSB, since it represented a sizeable potential resource in British Columbia. The poplar species are loosely identified by several names and to confirm the actual species we were referred to Mr.Bob Brash, District Manager, Dawson Creek Forest District. Mr.Brash confirmed that the species in question was in fact balsam poplar (populus balsamifera). Balsam poplar is also known as black poplar and balm poplar. An extensive literature search was conducted on the use of balsam poplar/cottonwood in the production of OSB. The literature review and a summary are reported here.
This report compares international standards for particleboard, waferboard, OSB, MDF, hardboard as well as cement bonded wood composite panels. Property requirements are discussed and comparisons are made between countries. Formaldehyde emission regulations were surveyed in eighteen countries.