A next generation sawmill

Overall, about 32 million euros were invested in the new sawmill. In a two-shift operation, this investment is supposed to pay off for Swedish company AB Karl Hedin, which is the sole owner of Toftan 1 and 2, in as few as six years. One might think that such a performance is not a challenge given the raw material prices, but it is not that simple. “We pay 65 €/m³ ex works”, says Arula with regard to the costs of “his industrial wood”. The estimated price for dimensions of more than 20 centimetres is at least 90 €/m³.

Toftan 2 is basically part of a wood cluster. On the adjoining premises, Granuul Invest produces pellets from logs, and the sawmill Toftan 1 has been cutting coniferous wood with a centre diameter of more than 20 centimetres since the late 1990s. Thus, the production site needs to purchase logs of various dimensions. The pre-sorting of the logs, which are then transported to the three sites, is done in the forest.

Keeping an eye on efficiency

For the author of this article, Toftan 2 is the first sawmill which would deserve the title “sawmill 4.0”. The control unit of the Nordautomation log yard is equipped with monitors which display a number in the upper right corner: the overall efficiency. Whenever the sawmill as a whole approaches the required efficiency level of 70%, a smiley slowly starts grinning – and so does the person operating the unit, since the wage of every one of the 18 employees also depends on the output of each shift.

When the logs enter the yard, they are measured and a cross section is taken which then decides in which box the wood ends up. This way, up to 50 logs per minute are sorted. The conveyors run at a speed of up to 210 metres per minute.

2200 logs per hour

The sawing line is located next to the log yard. The Svetruck log stackers feed the Veisto sawing line for thinner logs. An incredible 2200 logs per hour pass through this line. “Our record is 3000 logs”, Arula says proudly.

In Toftan 2, the logs are only debarked shortly before being cut. The Nordautomation infeed system transports the logs without interruption. Log after log passes the Valon Kone debarker at a speed of up to 180 metres per minute. Next, the wood runs through a Prologic 3D scanner which then sends the data of each log to the main Veisto machine. With a space of 40 centimetres between each log, the wood now passes through the movable saws of the HewSaw R200 1.1. Thanks to servo control, 70 to 200 metres per minute can be cut. When Timber-Online visited Toftan 2, the line was running at its “winter speed” of 46 logs per minute.

Even thinnest boards are better than wood chips

In the cutting process, the focus is exclusively on yield. A 50% log yield is Arula’s goal according to whom “anything is better than wood chips”. This can pose quite the challenge in the subsequent handling of the sawn timber: Even thin but common side boards of 12 x 70 mm have to be handled in this final phase. Already at the initial pre-sorting, up to 200 boards per minute each are required for the sorting of the main and side boards.

Ever-increasing speed

In Toftan 2, production speed increases steadily from the log yard to the sawing line and the subsequent handling of the sawn timber. This is why Swedish high-performance machine supplier Gunnarssons was responsible for the most challenging part. According to sales manager Jörgen Gunnarssons, his “board accelerator” was chosen for three reasons: “Speed, precision and fewer staff required.”

Five employees in the sawmill

Five employees work in the production hall: One operates the sawing line, one employee each is responsible for the pre- and post-sorting of the wood, one handles the packaging and one works as a stand-in.

Virtually all production processes are fully automatic and controlled and monitored via a computer. The production site could not do without this technology. It would be impossible for any employee to accurately examine the quality of more than 200 boards per minute or to insert the slats between the boards at a speed of 17 two-metre layers per minute at two adjacent stations. In theory, it would be possible to manually put the squared timber between the packages, but this would cost too much even in Estonia (average gross income: 1,250 €). For this reason, Gunnarssons installed a closed circular flow for slats and squared timber which are inserted, removed and returned automatically.

At the two pre-sorting units, two large conveyors take over the main and side boards from the sawing line. They act as buffers before the sorting and the forming of the packages to be dried.

Fewer personnel than usual

“Only one employee monitors the pre-sorting process. Behind him, the wood to be dried is stacked automatically. As a rule, Central European production sites have six or more employees at stations like this one”, tells us Stephan Lohmeyer, CEO of Scantech, whose company completed several projects with Gunnarssons in the past 40 years and took over the representative office in the German speaking area in 2017.

The wood is dried in Heinola chamber kilns. Once the desired humidity is reached, the packages return to the Gunnarssons components. Layer after layer is removed, the humidity is controlled (Brookhuis) and the surface is scanned again (Rema). Based on the information obtained, two trimmers implement these suggestions on how to optimise the wood by cutting on average 9000 pieces per hour.

Two-shift operation in 2019

Starting in 2019, Arula wants to implement a two-shift operation in the sawmill in order to reach his defined target, i.e. to cut 400,000 m³ of “industrial wood”. In addition to a two-shift model, the managing director considers increasing performance by an additional 20 %. “With some adjustments, we will be able to meet the required 240 pieces per minute”, comments Jörgen Gunnarssons who is convinced that his company will fulfil their customer’s wishes this time as well.

CGV GUNNARSSONS

Established: 1951
Management: Jörgen (sales manager), Tony (head of automation) und Jonas (head of construction)
Products and services: Complete systems for pre- and post-sorting, high-performance planing lines, automation
References: BSW, Derome, Holmen, Hedin, Moelven, Norra Skogsägarna, SCA, Setra, Södra, Vida etc.
Distribution (DACH region): Scantec, Feldkirchen/DE