Solid wood and residue yield analysis of small-diameter red oak logs

Forest Products Journal, Jan/Feb 2008 by Perkins, Brian, Smith, Robert L, Bond, Brian

Abstract

A yield analysis of solid wood and residues from 233 red oak small-diameter logs (6 to 10 inches small end d.i.b.) was conducted. The results indicated that 75 percent of the 1-inch lumber was grade 2 A and 3 A, while the remainder was No. 1 common. The container part yield from the cants ranged from 63 to 66 percent. The total solid wood and residue weight yield included lumber and container parts (35%) chips (29%), sawdust (26%), and bark (10%). This research adds the yield of lumber, cants, residues, and container parts from red oak in the 6- and 7-inch diameter ranges to existing yield data. The lack of upper grade lumber yield in the small-diameter timber (SDT) in this study suggests a log purchasing strategy for lumber manufacturers capable of using SDT and wanting to avoid producing upper grades of red oak lumber. Lumber and pallet part manufacturers could use the yield information in this study to estimate their capability to utilize SDT.

In the eastern hardwood forest, where small, nonindustrial, private forests (NIPF) are the principal forest ownership group, diameter limit cutting is often the predominate method for harvesting timber (Fajvan 2006). One motivation for NIPF owners to harvest timber is to generate revenue from their property. The largest and thus highest-value timber is harvested, and the smaller, lower-value timber resides in the stand. This practice, known as high grading, has occurred for decades in the hardwood forest and has resulted in more residual low-value, low-quality smaller timber (Nyland 1992). In the southern industrial forest, there has been a decrease in the pulping capacity from 139,880 tons per day in 1994 to 127,390 tons per day in 2003, along with a simultaneous decrease in the production of pulpwood from 180.8 million green tons in 1994 to 162 million green tons in 2003 (Johnson and Steppleton 2003). Viable markets are needed to address these trends of decreasing demand for and increasing supply of smaller, lower quality timber.

Research to identify lumber yield from small-diameter hardwood timber (SDT) (Hanks et al. 1980, Curnbo et al. 2004) discovered high proportions of lower grade lumber, and these grades are often used in pallet and flooring manufacturing. Craft and Emanuel (1981) and Serrano and Cassens (2000) investigated the yield of pallet cants and pallet parts from SDT. Cants, container parts, and lumber were produced to investigate the yield of lumber and container parts from SDT. Red oak was chosen for the yield study because of its relative abundance in Southwest Virginia, and the lack of engineered wood product markets for ring-porous species. In addition, red oak is a common species for the flooring and pallet market, which Cumbo et al- (2004) suggested as a likely market for lumber derived from SDT.

Utilization of SDT by lumber manufacturers may become more important as companies seek to reduce costs, avoid producing higher grades of red oak, and as log supplies become more limited to smaller and lower-quality logs. The objective of this research was to determine the volume yield of lumber, cants, container parts and residues from red oak SDT. This yield data were subsequently used in another study in order to address the economic viability of utilizing red oak SDT.

Methods

A yield study was initiated at a local hardwood scragg mill that is operated in unison with a pallet and container part manufacturing operation. This particular scragg mill had a shifting twin circular saw and rotating end dogging set-up, gang resaw, edger, and trimmer. The pallet and container part operation consisted of a cut-off-saw, gang resaw, part salvager, and a double-head notcher. The scragg mill was chosen because its design allows processing of logs into cants and lumber at high feed rates, and has low investment and operating costs (McCay and Wisdom 1984).

After discussions with mill personnel at the case-study mill, the minimum acceptable inside bark diameter was set at 6 inches due to limitations of the log processing equipment. Given this restriction, the small-end diameter range was limited to between 6 and 10 inches.

The red oak togs used in the study were sampled from the participating mill's log inventory. The target sample size was 50 red oak logs for each 1-inch small-end diameter class from 6 to 10 inches, for a total of 250 logs. The small-end diameter was measured along two axes (perpendicular to each other) and averaged, and the length of the logs was also measured. The range for each diameter group was from 0.4 below the nominal diameter to 0.5 above the nominal diameter. For example, the diameter range for the 6-inch group was from 5.6 to 6.5 inches. Each group of logs was marked with a unique color on the end of each log in order to facilitate sorting and tracking. All logs were below USDA Forest Service grade three logs due to diameter limitations of the USDA Forest Services' Standard Grades for Hardwood Factory Lumber Logs (Vaughanetal. 1966, Rastetal. 1979), and further analysis of log quality was not included in the study. The participating scragg mill produces lumber from relatively lower quality, smaller logs as compared to a grade sawmill. The logs in the 6- and 7-inch diameter groups were sampled from a log pile that had been sorted for species from their pulpwood inventory. A summary of the logs used in the yield study is summarized in Table 1.