Work reported in this study was carried out with the key objective of evaluating fasteners holding capacity in commercial wood panels for the purpose of exploring potential markets or expanding existing ones for OSB and other panel products in the upholstered furniture industry.
In order to have a better understanding of the upholstery furniture industry, visits were made to major upholstered furniture manufacturers in the Montreal area in November and December of 2003. These visits provided the research group with a comprehensive knowledge on the various types of wood materials and processing technologies being used at these plants, including ways of connecting the various components of the frames. Interviews with the plants staff indicated that fasteners holding capacity in OSB and other panel products are some of the major issues that are currently limiting the increased use of wood-based panels in the upholstered furniture industry.
In order to better understand the relationship between the fasteners holding capacity and the density distribution in panels, a comprehensive testing program was established. A total of 20 panels of medium density fiberboard (MDF), 16-mm thick, particleboard (PB), 16 mm thick, and oriented strand board (OSB), 11 mm, 15 mm, and 18 mm thick, with 4 replications each, were scanned using a commercial X ray system to obtain in-plane (horizontal) density distribution of the full size panels. In addition, basic panel properties (i.e., bending strength (MOR) and stiffness (MOE), internal bond (IB) and density profile) were determined. Sampling of test specimens from mapped panels was carried out in such away to cover low and high horizontal density zones.
Fasteners holding capacity tests including; lateral resistance of screws, edge and face withdrawal and head pull-through resistance of screws and staples were carried out. Correlations between fasteners holding capacities and localized horizontal density distributions were established in order to investigate how density distribution within the plane of the panel could affect the fasteners holding capacity. Investigations on the fasteners holding capacity in panel specimens subjected to static and cyclic loadings were made as well for the purpose of examining the effect of repeated cycles of loading and unloading events (i.e., short-term fatigue).
Findings from this study indicated that poor fasteners holding capacity especially on the edge of the panel is one of the key panel attributes that is currently limiting the use of OSB and other wood panel products in the upholstered furniture. Fastener driven in low density points or zones may fail at much lower load level than that driven in high density points with failure initiating at those low density zones and progressing to other zones from there (i.e., loaded end or edge distance). For the type of cyclic loading regimes used in this study (90 cycles at different load levels), no significant differences were observed.
Recommendations are given on how to improve the panel attributes in order to increase the fasteners holding capacity and resolve some of the technical issues limiting the market access of wood panel products in the upholstered furniture industry.