High-tech wood cutting in Sweden

“With our new automated saw, we achieve a speed of 150 metres per minute. This makes it the fastest band saw line in the world”, explains Johan Fredriksson from Swedish timber supplier Norra Timber. The modular line was supplied by the Swedish subsidiary of the American system builder USNR. It includes the flexible function terminals CPX/VTSA in key places for actuating the pneumatic and hydraulic systems.

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,” emphasizes 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.

Higher timber yields

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.

Faster commissioning

“The automation platform CPX and the function-integrated valve terminals CPX/VTSA that actuate all drives – no matter whether pneumatic, servo-pneumatic or hydraulic – also play a major role in our modular design,” remarks Jonas Ljung, design manager at USNR. The robust valve terminals with protection to IP65 can handledust, sawdust and wood shavings and are operated with different pressure zones. They actuate the many pneumatic cylinders of the type DNC and ADN that carry out positioning, clamping, centring and transport functions.

Hydraulic drives get their electrical pulses via the automation platform CPX. If greater flexibility is required because of the different dimensions of the logs, making the clamping and centring positions different, the pneumatic cylinders are actuated using the servo-pneumatic module CMAX via the CPX/VTSA. The pneumatic cylinders DNC used for this are additionally equipped with a displacement encoder to ensure precise positioning.

International fieldbus modules

The connection to the process control level is maintained by the CPX fieldbus module. “Here in Sweden we mostly use the PROFINET module, or Modbus® from Schneider Electric for other customers in Europe. In the USA and Canada, however, the band saw line can be supplied with the EtherNet/IP module or the DeviceNet® module on the CPX,” says Ljung when describing the high flexibility of the function-integrated valve terminals from Festo. Control cabinet assembly is not necessary with the CPX/VTSA because of the high protection to IP65. Thanks to this and the fieldbus technology, the time for installation and commissioning is reduced by 65%. There is less need for wiring, since there are also 80% fewer connection points. “As well as these hard facts, what’s also important for us is that Festo has been our partner in automation technology for more than 10 years and their automation experts are always on hand with service and advice – worldwide,” says Ljung.

Successful cooperation

USNR – known in Sweden until recently by the brand name Söderhamn Eriksson – is a longstanding partner of Norra Timber. USNR is a worldleading American corporate group in woodworking machines. With the integration of Söderhamn Eriksson, the Americans have gained a strong foothold in northern Europe and at the same time landed a technology leader in timber processing, since the Swedes have long had a name worldwide in the industry for speed, productivity and fl exible automation.

“We were very happy that USNR installed the new line in two weeks, as it meant that we were able to get back to working at full speed after four weeks. We had planned more than six weeks of downtime,” reports Project Manager Fredriksson from Norra Timber. The shorter commissioning time was made possible by the modular design of the band saw line. Reducers, log turners, conveyor lines and band saw units are independent units that are put together in the assembly halls of the Swedish subsidiary of USNR in Söderhamn with all of their automation technology before being installed as complete modules on the factory floor of Norra Timber.