Title: Manufacturing Hardwood Dimension Products Directly from Logs: Potential Opportunities
Author: Kline, D. Earl; Lin, Wenjie; Araman, Philip A.
Source: Proceedings, The Forest Industries 21st Wood Technology Clinic Show. pp. 1-19.
Description: When a hardwood log is sawn into lumber, over 16 percent of the volume is converted to sawdust. Furthermore, 12 percent of the log is converted to slabs and 17 percent is converted to edging and trimming pieces, all of which are chipped. Hence, less than 55 percent of the log is actually converted to lumber. Lumber must meet the requirements of specific NHLA grades and the traditional market expectation of minimal wane. Lumber lengths commonly range from 8 to 16 feet in even-numbered foot increments. Odd-numbered foot lengths are allowed but are not common. The lumber produced is then dried (5 to 10 percent shrinkage) and cut into dimension parts, eliminating undesirable features such as knots, splits, checks, stain, and warp. Typically, the part yield or the ratio of the volume of dimension parts to the volume of lumber is under 60 percent. Given all of these process conversion losses, the dimension yield from logs is less than 31 percent. This dimension yield can be well below 25 percent when considering low grade hardwood timber resources and the accumulation of inefficiencies for the many processing steps that are required. Many techniques have been suggested to improve the overall dimension product yield from logs, including back-gages, thin kerf saws, and computer automation. However, as the price of the wood raw material increases and as availability and environmental constraints further limit the volume of high grade logs that can be harvested, all available options for better utilizing our precious raw materials need to be explored. Virginia Tech has been investigating the option of cutting logs directly to parts, eliminating the lumber step. The objective of this investigation has been to determine if it is economically feasible to produce rough green dimension parts directly from No. 3 Grade red oak logs. This paper will highlight the findings of this investigation, including: 1) the potential dimension yield from No. 3 Grade red oak logs, 2) the productivity of a direct processing mill, and 3) the profitability of a direct processing mill.
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Kline, D. Earl; Lin, Wenjie; Araman, Philip A. 1993. Manufacturing Hardwood Dimension Products Directly from Logs: Potential Opportunities. Proceedings, The Forest Industries 21st Wood Technology Clinic Show. pp. 1-19.
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