Johan Fredriksson is a production developer in the Sävar Såg sawmill of the Swedish timber supplier Norra Timber, located in the middle of never-ending pine and spruce forests in the north of the country. This means that there is an abundance of wood. “However, given the tough competition in the timber industry, it is crucial to invest in advanced technology in order to increase productivity and therefore yields,” emphasises Fredriksson. A further highlight of the sawmill is a computer tomograph upstream of the band saw line. This assesses the quality of the logs, and enables an optimal cutting pattern. It also protects the system by detecting foreign matter such as rocks that could damage the saw blades.
In the sawing process itself, automation technology from Festo supports the modular design. Thanks to the flexible function terminals CPX/VTSA, the flexible fieldbus modules and the large number of standards-based cylinders DNC, the plant modules worldwide can be adapted to individual customer requirements. In addition, the reduced wiring for the valve terminal technology shortens the time needed for installation and commissioning.
An understandably proud Fredriksson reports higher yields: “Up to now, we could only use 50% of a log for sawn boards. With the new band saw line, we have increased the timber yield per log by 6%.” With this, Norra Timber wants to increase its annual output to 270,000 m³ sawn boards by 2020.The rest of the log is turned into wood shavings used by the pulp and paper industry as well as sawdust and bark for the sawmill’s own combined heat and power station to generate the heat for the kilns.
“The new band saw line from USNR is superior to other sawing technologies because it generates relatively little sawdust and wood shavings thanks to its fine and precise cuts,” says sawmill expert Fredriksson. A further benefit to boost productivity is the reduced distances between the logs along the conveyor section, thanks to the band saw line’s individual modules, allowing the high band speed to be used to the full.