Log sawing positioning optimization and log bucking of tropical hardwood species to increase the volume yield |
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| Authors: | Pedro Ah Shenga Peter Bomark Olof Broman Dick Sandberg |
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| Institution: | 1. Wood Science and Engineering, Lule? University of Technology, Skellefte?, Swedenpedro.shenga@ltu.se pedroshenga@gmail.com;3. Wood Science and Engineering, Lule? University of Technology, Skellefte?, Sweden |
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| Abstract: | The sawmill industry is a very important link in the Mozambique forest products value chain, but the industry is characterized by undeveloped processing technology and high-volume export of almost unrefined logs. The low volume yield of sawn timber has been identified as a critical gap in the technological development of the industry. To improve the profitability of the industry, there is thus a need to develop methods and techniques that improve the yield. In this paper, different positioning of logs prior to sawing and the possibility of increasing the volume yield of crooked logs by bucking the logs before sawing have been studied. A computer simulation was used to study the cant-sawing and through-and-through sawing of the logs to determine the volume yield of sawn timber from the jambirre (Millettia stuhlmannii Taub.) and umbila (Pterocarpus angolensis DC.) species. The optimal position, i.e. the position of the log before sawing that gives the highest volume yield of sawn timber for a given sawing pattern when the positioning parameters, offset, skew and rotation, are considered gave a considerable higher volume yield than the horns-down position. By bucking very crooked logs and using the horns-down positioning before sawing, the volume yield can be of the same magnitude as that obtained by optimal positioning on full-length (un-bucked) logs. The bucking reduces the crook of the logs and hence increases the volume yield of sawn timber. |
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| Keywords: | Roundwood sawmilling headrig jambirre Millettia stuhlmannii umbila Pterocarpus angolensis offset skew rotation |
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