Skip to content
PhD Johan Skog
PhD Johan Skog whose research gave fruit. Photo Kersti Bergkvist

New timber calculation delivers greater precision

Published: 7 June 2013

A new method for X-ray of logs developed at Luleå University of Technology (LTU) and SP Technical Research Institute of Sweden provides much higher accuracy than before and is ready for use in sawmills. PhD Johan Skog has developed the method in his research, presented in a new thesis at Luleå University of Technology.

- It will provide the sawmill industry new opportunities to control the manufacture of specific products with requirements on for ex. heartwood noun and density, and it will lead to less waste and improved profitability for mills, says Johan Skog.

Because wood is a biological material with high non-uniformity will also boards sawn from logs of similar size differ widely in characteristics. This means that a large proportion of the boards sawn will carry unwanted combinations of size and quality. With the help of 3D measurement frame in log sorting and X-ray frame, which many sawmills invested in, important quality information is obtained. Johan Skog has, based on these measurements, developed a method of calculation which means that the quality of the measurement can be increased further, where the log's outer shape is used to estimate the X-ray path through the log.

- By compensating for the walkway through the log, it is possible to improve the contrast of the radiographs, and this will in turn make it possible to calculate important quality variables like heartwood noun, dry density, moisture content and the presence of tree top cut he says.

The method has been tested on both sawlogs of pine and spruce. The new calculation method that Johan Skog has developed exhibits much higher precision than estimates based on X-ray images that are not compensated. He is currently working at SP Technical Research Institute of Sweden.