Because it offers good milling properties, especially for self-locking tongue and groove, medium- and high-density fiberboard (MDF and HDF) have gained acceptance as a substrate in the manufacture of engineered wood flooring (EWF). Depending on the component selected, delamination in the fiberboard or severe cupping deformation have, however, been observed. The aim of this study was to identify key design parameters in EWF made with MDF and HDF substrate, taking into account the density of the fiberboard, the characteristics of the face layer, and the type of backing process selected to meet quality requirements. A sliced face layer led to lower cupping deformation than a sawn face layer. With a sawn face layer, denser HDF provided a better substrate for EWF. The use of melamine-impregnated paper as a backing layer significantly contributed to reduced cupping deformation in all cases.
This article is the first to describe a process of manufacturing engineered wood composites that combine two nonwoven textile technologies: bicomponent fiber and needle punching. Hardwood fiber was blended with 10 percent urea formaldehyde and formed into mats. The mats were sandwiched with polypropylene/polyester bicomponent fibers and then needle punched. Needle punching was done by means of barbed needles that oscillated in a vertical direction with regard to the surface of the fiber mat. The barbed needles mechanically interlaced the bicomponent web to the wood-fiber mat and pulled some of the polymer fibers through the thickness direction of the mat. During hot pressing, the polypropylene sheath of the bicomponent fiber flowed, bonded with adjacent wood fibers, and coalesced with the sheath of the adjacent bicomponent fibers. The mats were pressed until the urea formaldehyde was fully cured. Bending and tensile properties of the needle-punched wood composite were assessed and compared with medium-density fiberboard (MDF). An average increase in storage modulus of 40 percent was observed for the 640-kg/m3 panels and 48 percent for the 550-kg/m3 panels. A mean longitudinal tensile modulus of 923 MPa was measured for the laminate panels. This is an improvement in tensile modulus of elasticity of almost 34 percent over the wood-fiber core material.
Test of fire-retardant-treated (FRT) laminated veneer lumber (LVL) indicated moisture gain under adsorption and moisture loss under desorption conditions. The moisture content of FRT specimens increased considerably under adsorption conditions compared with control specimens, while it was not found to be a significant difference under desorption conditions. The statistical findings revealed that impregnation with chemical salts had significant effects on the expansion properties. Fire-retardant treatment also had meaningful effects on the swelling properties. However, the expansion and swelling properties of the LVL were not affected significantly by the veneer drying temperature. Generally, equilibrium moisture content of LVL decreased with increasing veneer drying temperature. The interactions between fire-retardant chemicals and veneer drying temperature were also found to be insignificant.
Monitoring the moisture content of lumber is an important part of the manufacturing process. Lumber that is too wet or too dry will have a lower value than properly dried lumber. The cumulative sum (CUSUM) chart is proposed as an alternative to traditional control charts for detecting small sustained changes in the mean charge moisture content of kiln-dried lumber. Charts are presented and interpreted for two kilns. The CUSUM chart readily detected changes in the mean moisture content that were not detected with an X-chart. For the CUSUM chart to work well, the process must be in a good state of control with the mill’s average moisture content near the target moisture content.
The effects of knots on the bending strength of dimension softwood lumber were investigated for two Alaska-grown species, yellow cedar (Chamaecyparis nootkatensis) and Sitka spruce (Picea sitchensis). An empirical measure of the bending strength ratio for knots was determined by comparison of full-size in-grade test results to corresponding test results from matching small clear specimens. The empirical strength ratios were compared with theoretical strength ratios calculated using existing formulas given in ASTM D245 (ASTM International 2005). It was determined that existing formulas do not provide accurate estimates of bending strength ratio for the two Alaska-grown species under study. Additional predictor variables were used to develop a new model to estimate the influence of knots on the bending strength ratio. Comparison of new formulas to existing formulas demonstrates that this new model is more effective at accounting for variations in bending strength ratio caused by the presence of a knot. It was concluded that the use of the models presented in the 2005 version of the ASTM standards for knot bending strength ratios should be reevaluated. This is especially important for any new timber species being added to the design tables. Species-specific models for estimated bending strength ratios, utilizing additional predictor variables, would help to better predict the effect of knots on bending strength of structural lumber.
Diversity in land management objectives has led to changes in the character of raw material available to the forest products industries in the US Pacific Northwest. Increasing numbers of logs from small-diameter trees, both plantation grown and those from suppressed or young stands, now constitute a large proportion of logs coming into the mill yard. Wood coming from plantations or young stands has different properties than wood coming from older, suppressed stands. This research examined wood properties of small-diameter plantation-grown Douglas-fir and western hemlock with the goal of a better understanding of utilization of small-diameter, fast-grown trees for use in manufacturing engineered wood composites. Twelve trees of each species were harvested and three bolts cut from each tree. Each bolt provided samples for X-ray densitometry profiles, compression, and tension parallel to grain and flexure tests. Both species were found to have a very high proportion of juvenile wood. Most wood properties decreased with increasing vertical position and increased with increasing distance from pith for both species. Increased competition for wood fiber, which accounts for as much as 25 to 35 percent of total wood composite (such as particleboard, medium-density fiberboard and oriented strand board) manufacturing costs, necessitates an understanding of raw material properties and their variations. This knowledge could assist in optimizing the manufacturing process and maximizing efficiency of wood raw material use, thus increasing profits.
Estimating yield from lumber cut-up in rip-first rough mills for material management and job costing purposes is uncertain unless simulation models are used. To augment the toolbox for industry practitioners, a novel yield estimation model was derived using linear least squares techniques and data derived from an orthogonal, 220–11 fractional factorial design of resolution V. The model estimated 450 of 512 cutting bills tested within 1 percent absolute yield. However, cutting bills that do not adhere to the model’s framework suffer a larger estimation error. The least squares estimation model thus is a helpful tool in ranking cutting bills that adhere to the model’s framework for their expected yield levels and facilitates the selection of part sizes to be included in cutting bills. Further research is needed to make the model useful for a wider range of cutting bills.
In this article, we report on the effect of internal log defect scanning on the gain in lumber value recovery for five hardwood species, consisting of black cherry, hard maple, yellow poplar, red oak, and white oak logs. A total of 29 logs, 6 logs per species and 2 logs each for log Grades 1, 2, and 3, were scanned with a medical X-ray computed tomography scanner to acquire their cross-sectional images. The one exception being for red oak logs, for which we scanned two Grade 1 logs, one Grade 2 log, and two Grade 3 logs. These logs were then sawn in the sawmill to determine the actual value recovered from each log. Virtual logs constructed with the scanning images of these logs were then sawn on the computer using the TOPSAW software. Based on simple live sawing simulations, overall the average value gain for all species and grades was 46%, while the gains for black cherry, hard maple, yellow poplar, red oak, and white oak were 42, 33, 83, 24, and 60 percent, respectively. The average gains for Grades 1, 2, and 3 logs were 27, 47, and 97 percent, respectively. Regression analysis of the gains indicated that while there are no significant differences among the species, the gain for Grade 3 logs was significantly different from other log grades.
The moulder is one of the most widely used machines in the wood industry. Its function is to cut stock with rough dimensions to a finished width, thickness, and cross-sectional shape in one pass, making it cost effective to produce mouldings, floors, window and furniture components, etc. Today’s moulders are fast, safe, flexible, versatile, precise, and productive. Many different configurations can be selected when specifying the purchase of a moulder. The Moulder Economic Calculator (MEC) was developed to determine the economic impact of choosing different moulder configurations. The calculator uses input data on machine price and purchase method, machine configuration, production parameters, and production costs. The MEC program gives three types of outputs: surface quality, productivity, and costs. The MEC program is a flexible tool that allows the user to estimate the cost of machining one linear foot of wood. Some capabilities of the MEC program include determining the effect of machine price on machining cost, the effect of setup time on production time, and the effect of machine configuration on machining cost. In this way, the MEC program allows the user to compare between different machine configurations and determine which best meets the user’s cost, production, or flexibility requirements. The model was taken to Weinig USA, where their experts reviewed the model and offered their input.
Evaluations of products based on visual stimuli are at the same time both subjective and important. The aim of this study was to examine the relationship between the visual properties of wood flooring and people’s reactions to computer visualization of interior wood products. The research strategy involved showing digital pictures of the same room, but with different wood floorings. The impressions of potential consumers were measured by means of rating scales for each descriptive word. This was done using the method of Kansei engineering, in which statistical connections between properties and semantics (descriptions) were analyzed. The research presented here contributes to theory and practice in two important ways. First and most important, the study shows that the chosen method is suitable for measuring people’s preferences on visualizations of interior wood. Second, the results indicate that certain properties are important for a floor to be judged as ‘‘good-looking’’ and others for a floor to be deemed ‘‘modern’’ or ‘‘vivid.’’
This article focuses on branding in the forest products industry. It examines corporate and product cobranding. Traditionally, in the forest products industry, uses of new industrial product brands have been promoted in a cobranding context with their better-known corporate brands. This research, using data collected from residential homebuilders in the northwestern United States in the spring and summer of 2007, explores the brand associations of quality, leadership, and environmental stewardship related to corporate and product brands in this cobranding context. Specifically, the research explores the transfer of the noted brand associations from the corporate brand to the product brand as well as the transfer of these brand associations from the product brand to the corporate brand. Resulting analysis of the data noted that stronger rated brands significantly improve ratings of weaker brands generally, while weaker brands do not significantly devalue stronger brands in the cobranding context.
Prodealers are building materials suppliers whose client base comes mostly from the homebuilding industry. Because they represent an important channel for wood products, a 2007 survey of US prodealers examined (1) lumber attributes demanded, (2) products and suppliers requirements, (3) trends in substitution between countries supplying lumber to the United States, and (4) trends toward prefabrication of structural components. Forty-six prodealers were surveyed; most answered for multiple stores. On average, respondents purchased 60 million board feet of lumber in 2007, and their overall consumption was estimated at 2.76 billion board feet. By far, the most common grade in the prodealer segment is dimension lumber (No. 2 and Better), and the most common type is the spruce-pine-fir species group (SPF). Within the sample, 5 percent of US lumber imports came from offshore. Canada supplied 51 percent of the lumber purchased by respondents, and the United States supplied 47 percent. Wane as well as warp and twist were consistently identified as the most challenging lumber attributes for prodealers. Product quality was identified as a primary reason for changing lumber suppliers. In characterizing properties of the dimension lumber imported from Europe to the United States, it was found that European lumber stands out mostly for visual appearance and low wane. For customer support and timely deliveries, respondents tended to favor US mills. The study suggests that customers are not fully satisfied with lumber, especially with regard to wane and straightness, and that lumber quality issues may be more important today than in the past.
In 1977, the value of wood household furniture shipments from domestic manufacturers exceeded kitchen cabinet shipments by 170 percent; conversely, in 2006, shipments of cabinets exceeded shipments of furniture by 78 percent. The most apparent reason for the decrease in domestic furniture shipments is the increase in furniture imports, whereas cabinet demand has increased because of the popularity of larger kitchens and the robust housing market prior to 2006. However, there also are less apparent factors. A large portion of domestically produced wood furniture is sold to consumers from retail stores whose buyers ordered product at semiannual furniture markets. Meanwhile, a growing volume of cabinets are designed and ordered by consumers at home improvement centers. Furniture manufacturers carry large volumes of finished products in inventory, while cabinet manufacturers carry low inventories. Furniture has become a quasi commodity that is priced within narrow ranges depending on quality, whereas sale methods for semicustom and custom cabinets allow consumers to order the species, finishes, and features they want. The price competitiveness of the furniture industry has allowed imports to become the major source of product. The need to price furniture at levels competitive with imports has also resulted in a greater use of composite materials versus lumber and dimension stock. By contrast, kitchen cabinet manufacturers are using greater volumes of lumber and dimension. While these factors have resulted in a contrast in fortune for the wood household furniture and cabinet industries in the United States, possible opportunities exist for the reemergence of parts of the domestic furniture industry.
Urbanization of forestland has the potential to reduce the timberland base indefinitely. Wood-using industry located in areas with declining timberlands may be forced to expand the range of procurement operations to meet production requirements. This article examines 11 different land use and land cover variables as predictors of woodshed area for sawmills in the northeastern United States. Based on woodshed maps provided by 175 sawmills in seven states, geospatial analysis and multiple regression are used to test the hypothesis that mills in areas with higher proportions of nontimber land have larger woodsheds. Results indicate that mill characteristics, not landscape variables, are the strongest predictors of woodshed area. Although some cover types, including farmland and open water, are associated with larger woodsheds, none of the measures of urbanization used in this study are significant predictors of woodshed area. If urbanization is leading to a reduced flow of sawlogs, the explanation for the lack of observed effects of urban cover on woodshed area may be tied to the flow of sawlogs from terminal harvests, prior relocation of sawmills out of urbanizing areas, or the implementation of alternative procurement and production strategies that help sawmills remain competitive as local wood supplies tighten.
The impacts of additional log sorting on production and cost per ton for mechanized, tree-length southern pine harvesting systems were evaluated. The analysis included evaluation of extensive data sets of weekly production along with short-term field time studies to directly measure the impacts of sorting on production. For this study, a product separation, or sort, was defined as a separate pile generated by the loader operator. The data were used to create a model to evaluate log sorting impacts on production and costs. Tree-length harvesting systems encountered weekly production losses when sorting more than six products, while modified tree-length harvesting systems using roadside processors lost production after nine product sorts. Hourly production was significantly impacted by both operator technique and the type of product handled. Operators who processed wood in advance of truck arrivals and loaded trucks from processed piles loaded trucks in 60 percent less time than loader operators who processed stems while loading. Increasing the number of sorts often required more processing while loading since the room to store processed wood under stationary loaders is limited. Adding precut sorts significantly reduced production over that seen with an additional tree-length sort, due to the additional processing and loader movement with multiple stem pieces. With the current product price differentials typical to southern log markets, we did not find increased net revenue to the landowner from additional sorts. In fact, we found that at current prices additional sorts can reduce revenue by 6 to 15 percent.