University of Tasmania
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Methods to increase the efficient utilization of hardwood lumber to produce high value products

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posted on 2023-05-27, 23:55 authored by Davis, KJ
This work aims to demonstrate the potential benefits of using board-scale high-resolution digitized information to improve the utilization and description and communication of the visual characteristics and properties of hardwood lumber within the appearance hardwood lumber supply chain. Current practice in the appearance hardwood timber industry is to batch boards according to grading standards that largely disregard the variation caused by natural growth characteristics, such as knots, splits, grain variation, and decay, which largely determined the physical and mechanical properties of boards. These standards describe acceptable characteristics as a boundary condition. There is little assurance that any grade, other than those that contain very few characteristics, can be efficiently and effectively manufactured into high-value products. Often this results in loss of potential utility and value of lumber that contains a high frequency of growth characteristics, such as knots. The physical and mechanical properties of manufactured homogenous (uniform) materials, such as steel and paint, are described and communicated precisely and accurately within the supply chain. This provides a high level of assurance that material will perform as intended and required. However, this level of assurance is not provided by most grading systems used for natural materials, such as hardwood lumber. This reduces the ability to obtain the best-suited boards and to accurately predict the visual outcome and manufacturing expense for hardwood lumber that contains frequent growth characteristics. The problem occurs largely because of the lack of high-resolution information describing the characteristics of lumber and the absence of a meaningful way to exchange such information between lumber producers and high-value product manufacturers in the appearance hardwood lumber supply chain. To address this problem, a system was developed to determine ways that the exchange of high-resolution board-scale information describing the size and distribution of growth characteristics within the supply chain would improve the utilization of hardwood lumber. The system involved four areas of research. The first area focused on developing a characterization module to describe knots using digital images. The second area explored methods to improve the ways that an acceptable range of knots could be defined and selected. It also explored the visual outcomes of the effects of different sizes and types of knots using a wood appearance panel as an exemplary product. The third research area developed a novel lumber sorting approach based on the ways that useable areas of a board were defined by the users. Finally, the fourth area determined ways to match the best-suited group of boards to different product part requirements. User input directed the way the system simulated the batching and processing of boards. The system's capacity enables greater detail in the communication between producers and manufacturers in the appearance hardwood lumber supply chain. This capacity overcomes the current lumber grading systems by providing the necessary framework to pass and use detailed digital information describing the physical properties among members of the supply chain. The system was built around the occurrence of knots in boards. However, the system could be expanded to include other growth characteristics that allow an even more detailed prediction of the yield of product parts and the potential visual outcomes available from different resources. The system demonstrated a novel lumber sorting approach that could more effectively differentiate boards into groups, a means to achieve a desired visual outcome from a population of available boards, and a way to determine the manufacturing costs for products. Overall, the system was tested on two short-rotation, fiber-managed, plantation-grown hardwood species from Tasmania, Australia. The system indicated that, despite the common belief that lumber produced from these resources is difficult to utilize for the production of high-value secondary products, a significant proportion (75 percent, and 77 percent for Eucalyptus nitens and E. globulus, respectively) of the boards from the study produced a high yield of pieces for appearance wood panels that had different visual attributes caused by the inclusion of different sizes and types of knots. Currently, there are nearly 1 million hectares of plantation hardwood forests in Australia, of which, approximately 92 percent of the volume of harvested timber is exported as low-value fiber for the pulp and paper industry. The findings in this study suggest, that with appropriate technological developments, lumber produced from short-rotation, fiber-managed resources from Australia could be utilized in higher-value appearance products and markets. The system was tested by simulating the potential production of appearance wood panels with differing visual attributes caused by different sizes and types of knots. It was demonstrated the production of appearance solid wood panels could be viably produced from lumber produced from plantation resources. Because the production of standardized solid wood panels is relatively straightforward, panel products present a means to contribute to local economies, such as the State of Tasmania. The findings also suggest an approach for the uptake of undervalued and underutilized hardwood resources in other regions, such as North America.


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