RADIAL STICK SAWING OPTIMIZATION

Stability in wood is related to moisture content and annual ring direction. Many manufacturers choose radial material for less shrinkage and swelling ratios and uniform shape change avoiding deformations especially for layered and joined materials. Sawmill operators usually prefer quarter sawing diagram to obtain radial boards from logs for this purpose. However, quarter and another diagrams give solutions for only boards that have larger dimensions than sticks, which are commonly used layered materials. In this study, radial stick sawing optimization from logs was aimed. For this purpose, commercially preferred logs with 200mm, 300mm, 400mm and 500mm diameter, and cylindrical shape, were drawn in CAD program. Commonly used sawing diagrams (live, quarter, around) were tried empirically basing on cross sections. However, studies showed that when tangential boards were sawn to obtain radial sticks, all sticks could not be radial due to annual ring direction, especially at the end of boards. Therefore, some diagrams were modified to obtain maximum radial stick yield. Results showed that the radial stick yield can reach 57,8% and the yield increment reached max. 28,9% (12,97% in average) when the all diagrams for all logs were considered. Especially around sawing method gave maximum radial stick yield. It is originated from the diagram, which normally gives radial sticks from tangential boards. Furthermore, modified sawing diagrams gave better yields from commercially preferred diagrams. However, sawing process is becoming extended and complicated with them. Otherwise, it is suggested that log sawing optimization programs should calculate lower dimensions than boards with considering secondary sawing process and annual rings can be drawn in program or scanned for evaluating board is radial or tangential.

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