Sapwood moisture-content measurements in Pinus sylvestris sawlogs combining X-ray and three-dimensional scanning

Abstract

Because today's sawmill processes are not fully adapted to the variability of the raw material, it is crucial to sort sawlogs according to material properties in order to process the wood efficiently and to obtain high-quality end-products. One material property that could be used for sorting is the moisture content (MC) of the sapwood, an important parameter for both the processing and the end-products. Most sawmills use three-dimensional (3D) scanners to sort logs and some have also invested in X-ray scanners. Previous studies have shown that, by combining raw data from 3D and X-ray log scanners, green sapwood density and dry heartwood density in Scots pine sawlogs can be estimated. In this study, the method was used to estimate sapwood MC in green logs. It was found that the MC estimate could be used to separate the logs into groups with high and low MC, correctly classifying all logs with MC below 100% as low MC logs. Out of all logs, 70% were correctly classified. The MC estimate could also be compared to the dry density-dependent maximum MC and used to identify logs that have actually started to dry.

Keywords:

• 3D scanning
• green density
• log sorting
• MC
• Scots pine
• X-ray scanning

Acknowledgements

This work was financially supported by TräCentrum Norr, a research programme jointly funded by industrial stakeholders, the European Union (ERDF) and the county administrative boards of Norrbotten and Västerbotten.