On the frontline – SCANNING & OPTIMISATION
Seeing through the bark
Sweden’s biggest sawmill, SCA Bollstabruk, has had MiCROTEC’s
Tomolog system up and running since the start of last year. The mill immediately enjoyed a 1%
increase in yield but that was just the beginning
production that wouldn’t be eternally grateful to know how the logs look inside before breaking them down. After years of R&D, MiCROTEC has realised that dream.
T The new system is called
Tomolog and the key to its effectiveness is the CT.LOG, featuring an advanced rotating x- ray source that the South Tyrolean company presented at Ligna last year. The three-dimensional x-ray scan has a processing speed of 200 m/minute, which helped convince leading forest products group, SCA, to install a Tomolog at its Bollstabruk mill, which is currently the most efficient
he internal optimisation of logs has always been a dream – there isn’t a head of
sawmill in Scandinavia largely because it produces a radiograph from two x-ray sources for every log. Based on imaging, the volume without bark, knots and other wood defects are detected and recognised. “To come to the point –
Tomolog works so well that another system has been ordered for the SCA sawmill in Tunadal,” MiCROTEC said.
Base camp: 1 million m3 /y
Bollstabruk is one of the locations in which SCA is heavily investing. The sawmill is by the river Ångermanälven – logistically a great location because the sawmill can be serviced by deep-sea vessels.
In 2011, the sawmill produced
MiCROTEC’s Tomolog system has helped make SCA Tunadal one of the most productive sawmills in Europe 460,000 m3
the 1 million m3
of pine products out of processed. The
volume for next year is supposed to be significantly increased to 1.4 m3
and every log within that will
have a 3D image generated. “After the manual acceptance, the logs are sent on longitudinal conveyors to the scanning station,” SCA’s Jimmy Hörnström said. “The Tomolog x-ray scanner is located there as well as a DiShape 3D-scanner and a Screenlog colour-scanner. Tomolog analyses the internal structure. DiShape determines the characteristics of the surface including bark. Screenlog generates head and butt images of the log. “All three systems together build the Logeye system,
MiCROTEC’s integrated multi- sensor quality scanner for logs. The multi-sensor scanner uses x- ray analysis, 3D reconstruction and colour scanning similar to the Goldeneye installations for secondary manufacturing.”
Safety first The Tomolog scanner seems unimpressive from outside but the brilliance is in the detail. Two x-ray sources, geared with 160 kV, send their radiation through the wood. On the opposite side, two sensors receive the signal that, depending on the density of the irradiated wood, has been more or less absorbed. Starting from here, an accurate model can be calculated. “One learns at an early age at the dentist that ionizing radiation
FEBRUARY/MARCH 2012 | International Forest Industries 25
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