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Large diameter logs for the chipper canter

Friedrich Rothmund (on the right) and DI (FH) Alexander Gleich from Linck show the new saw line developed in a Team.

New saw line ensures supply of glued-laminated timber material

The new Linck saw line provides more and more raw material for the saw- and planing mill Rothmund. A chipper canter-circular saw combination processes 60.000 m³ round logs/year whereof many have a small end diameter of more than half a metre.

Straight out of the picture book: The sawmill Rothmund in the Klettgau lies in the winter sun. Managing director Friedrich Rothmund is driving the timber grab on the frosty log yard. And a brand-new Linck saw line for future transforming of 60.000 m³ softwood logs into high-quality lumber is sparkling in the sawmill building. The majority of the lumber is designed for further in-house processing. More than 60 cross sections are required for producing solid structure timber. As the existing gangsaw could no longer meet the requirements, the company Rothmund ordered a chipper canter-circular sawline about a year ago which impresses by the diameters processed. Small end diameters of 50 cm are not uncommon.

Here is where its starts: The saw logs having passed a 3D-scanner are positioned in the chipper canter infeed to guarantee optimum added value.

Lumber supply for further processing must be ensured. First of all the saw mill Rothmund sees itself as producer of raw material for solid structure timber, duo beams, laminated construction timber and to a small extent for window scantlings needed in the Rothmund production facility for edge-glued panels next door. The two brothers Friedrich and Markus Rothmund started their edge-glued panel production in 2001 and since then they have established themselves in the Southern part of Germany, Switzerland and Austria. The increasing further processing needed more and more raw material which Rothmund wanted to produce in its own facilities from local and often large diameter wood. The reduced space available made it necessary to sort the logs with sorting increments of 4 cm into the concrete bins. However, the optimum cutting pattern for a saw log with 40 cm small end diameter is sometimes different from the one for a log with 43 cm diameter. "This situation required flexible machines that can be adjusted quickly," explains Alexander Gleich from Linck who accompanied the project from the beginning.

Chipper canter first, then circular saws. The saw line starts with the log loading station on the western side of the sawmill building. A Microtec Discan scanner measures the saw logs three-dimensionally. Optimising is carried out according to the sales prices for lumber assortments. After having passed the four rotating rollers at 70 m/min. feed speed, the saw logs are transported through the chipper canter VM50 followed by the primary saw unit CSMK 375-A2/B2 with two each saw flanges on both sides. Up to six sideboards are sawn off at the same time. "The sideboards produced are up to 66 mm thick so that they can also be used for solid structure timber if they have a corresponding quality" explains Rothmund. As prices for such timber are considerably higher than for the typical 23 mm formwork, the saw logs are sometimes asymmetrically processed in the machine so that there are no boards on one side, however high-quality ones on the other side.

Attention to detail: The hydraulic valve panel shows the care with which Linck is planning his plants - for example with regards to easy maintenance.
At a glance: Following the chipper canter, boards are separated(1) and fed through the horizontal split saw (2) and double arbor circular resaw (3) towards the sorting plant (4), cants go back to the beginning (5).

… eight products for solid structure timber ready. Following the breakdown saw, the sideboards drop onto the belt conveyor leading to the existing board edger. The cant is now transported through the resaws which are out of working range. It is then transported back past the right-hand side of the plant and beyond the still operative gang saw to be loaded for a second pass. The 3D-scanner measures the two-sided cant again. The spiked rollers grip the cant for a second pass through the chipper canter and the breakdown saw unit. Again sideboards are sawn off. The four-sided cant is now fed into the horizontal split saw HKM360-A2 splitting it horizontally if required. The following double arbor circular saw CSMK 375-A1 with a fixed saw setting of maximum 450 mm length is ripping the cant. Up to 21 products are possible in combination with the horizontal split saw. A 4 m long saw log with 40 cm small end diameter, which operator Branko Misanovic has on its screen, is for example split into four products 66 x 111 mm and four products 66 x 175 mm. Cross conveyors finally feed the main products to the new sorting plant from TC Maschinenbau, St. Veit an der Glan/Austria. More than 70 % of the main products are used for further processing.

Everything under control: Machine operator Branko Misanovic in his tidy control cabin.
The operator terminal is showing amongst others the current cutting pattern and the power consumption.

Clear control. Nobody refers to "mega sawmills" any more. Sawmills like in Klettgau are more likely the future of the domestic sawmill industry. This is also Rothmund's opinion and he remembers the order placing. "I told: This is the budget, the saw line shall meet the given requirements and I intend to process 60.000 m³ round logs per year". Linck convinced him with its technology. He talks about "the Mercedes among the saw lines". Many details leave indeed a good impression starting with the robust machines, over the well performed hydraulic system up to the visualisation on the screen on which the machine operator can see all important parameters. For example: Which cutting pattern is processed? Which orders are handled? Where are the logs and cants in the saw line? At the top left part of the screen a needle is showing the power consumption, a value which is used for automatically setting the feed speed. Despite the saw line is rather new, Misanovic is sitting rather relaxed in his seat now exercising monitoring functions only.

„Money is made with optimisation“". A good hardware is only part of the success. After having asked which part of the plant pleases him best, Rothmund states "The optimisation system - as profit is made here". With round log prices of 92,50 €/m³ ex forest road (forest measurement) and more and more reduced deductions for large diameter logs, the raw material has to be utilized in the best possible way. The optimisation system is permanently working in the background calculating the optimum cutting pattern for each log from seven main product dimensions and five sideboard thicknesses. Recovery values of more than 70% are achieved with particularly large logs and certain cutting patterns. But not only the quantity counts. The saw line represents big advantages for the production of solid structure timber (SST). The possibility of making a horizontal cut with the circular split saw results in SST-raw material far away from the core. Rothmund: "This is the best quality. There is nearly no warp. However this is possible with large diameter logs only". Compared with the gangsaw, sawing accuracy considerably increased. The higher accuracy now saves 1 mm with each single saw kerf cumulating to a considerable sum with 60.000 m³ round logs per year.

Second round: The 3D-scanning system measures the two-sided cants a second time prior to finally splitting them in the Linck line.

Tailor-made suit.Central Europe probably has to say goodbye to the "saw mill in the open countryside" which means that Linck engineers will have to adapt their saw lines more and more into existing sawmill buildings. The space available in the sawmill Roth was 30 m only. Not much for integrating the rotating rollers, three saw units, a chipper canter and the sideboard drop-off station. Up to 5.1 m long saw logs can be processed. The full-length logs make it possible to precisely set the crosscuts on the Holtec log yard. Six employees only work in the sawmill building. This high workplace productivity is important as the sawmill is only one kilometer from the Swiss border and therefore qualified personnel is expensive.

Friedrich Rothmund Säge- u. Hobelwerk

Founded in 1929
Site Klettgau/Germany
Managing Director Friedrich Rothmund
Processing capacity 60.000 m³ round logs per year (50 % spruce, 30 % fir, 10 % pine, rest: Douglas fir, larch)
Products Raw material for solid structure timber production, laminated timber, window scantlings, lumber, packaging material