Sawn timber recovery rates of some PNG species of logs.
The results are presented of investigations into the sawn timber recovery rate of representative species of logs from Papua New Guinea, with a discussion of the factors which influence this. The latter include log characteristics and sawmilling efficiency. Efficiency is discussed in terms of equipment quality and type, and sawmill management (equipment maintenance, and training and rotation of personnel). Log quality is discussed in terms of size, defects and storage method. It is noted that the choice of sawing pattern is governed by log size, quality, mill type, processing method, product sizes, etc., and that this also influences recovery rate, as does the size of sawnwood. Six species were included in the investigation, which was undertaken at the sawmill of the Timber Industry Training College in Lae. Each log was marked and every piece of sawn timber derived given a corresponding mark so that sawnwood could be matched up: sawing was done by breakdown saw followed by secondary breakdown operations to the required size. Average recovery rates for the 6 species were: Dracontomelon dao, 54.5%; Palaquium spp., 39.5%; Diospyros spp., 44.5%; Dillenia spp., 47.9%; Terminalia spp., 46.0%; and Octomeles sumatrana, 69.3%. The overall recovery rate from this trial was 50.8%, compared with a rate of 43.5% for 8 species processed by the Stettin Bay Lumber Company. Separate recovery rates are given for each of these 8 species, but although some of the species are the same, they do not have the same recovery rates as the equivalent species in this study. The recovery rate from this study is considered low, and the cause is given as low quality of the logs due to storage in the logyard for several months. It is noted that it is not possible to quote a particular recovery rate for a particular species because of the wide variation found.