21 September 2017

Rotary cutting/peeling, the future of large trunks

Today, large trunks find themselves on the horns of a dilemma, with plenty of trunks available but great difficulty making a profit with them. Sawmills are reluctant to tackle this abundant French resource because of the conversion method and its consequent low yield.

We met up with Christian Lallia, the director of Finnso Bois. As a partner to Finnish and Canadian companies, he has been looking into rotary cutting and the resulting products that can provide expanded outlets for large trunks.

What explains the poor profit margins on sawn large trunks?

For 15 years or so, lots of interested parties have been searching for ways to optimize the sawing of large trunks, but the market is having a hard time finding a good economic solution. For one, the quality of large trucks can vary wildly. This is not a problem for good quality large trunks—which sawmill operators can extract good value from in specific markets—but the medium and low qualities (poor mechanical properties, discolouring, etc.). Sawing a large trunk costs a third more than converting small-to-medium stock. To make up for this competitiveness penalty, we have to either buy large trunks cheaper, which owners do not take kindly to, or we must sell them at a higher price, which the market is not ready to pay.

A canter line can output up to 100 cubic metres an hour with a single operator; for large trunks, make that 20–30 cubic metres and a team of operators. In a market veering toward more and more standardization, even if we manage to bring conversion costs down to a minimum, there will still be an overcost whatever solution is used to produce standard cuts.  Sawing nonetheless remains a valid solution, the more so when certain new factors open the way to a better payback.

What are today’s most suitable techniques?

Large logs are by definition big and heavy; they demand the use of saw lines with extremely tough and therefore costly equipment. They do not lend themselves to improvisation.

I see an alternative solution as being more appropriate to large trunks: rotary cutting and peeling technology. I’m not claiming this as my brainchild; it has been used for good many years in Sweden and Finland, where key players in the sawing market redirect their biggest logs to their rotary cutting machines. Rotary cutting produces wooden “sheets” that can be used for example for plywood and laminated veneer lumber (LVL). By reconstituting a product from sheets having variable specific properties, you get more out of the wood, with yields exceeding 50%. The target market for these products are construction, transport, packaging, and others.

Value recovery from medium and low quality stock is thus optimized, fetching a higher selling price. Given the market growth of around 2–5% per year for softwood ply, a market measuring more than 2 million cubic metres in Europe (with a self production of only 50%), this becomes an excellent outlet for large trunks. Another advantage of rotary cutting is the short turnaround time between the log’s arrival at the plant and shipping of the final product, notably due to the drying time of only a few minutes.

So in your opinion what is the best current outlet for large trunks?

As I stated earlier, the sawing of high quality logs for high added-value applications will continue for a long time to come. For lesser quality logs, however, the rotary cutting technique is very relevant and can be used for making boards, panels, planks, and beams. LVL is ideal for a whole host of applications, structural or otherwise (such as furniture). It fully meets the requirements for standardized timber as well as for the high-performance construction timber demanded by architects. Today, the biggest European and French manufacturer of LVL and gluelam is the Finnish-Swedish Stora Enso group, who recently started up its first rotary cutter and who, with its Finnish factory, has already gate-crashed the European top three club of LVL manufacturers.

France has a long tradition of rotary peeling and plywood (over 500,000m³/year in the 1980s), often made from African imported timber but more and more from home grown timber. Well-managed family businesses are engaged in dynamic development, certainly helped by the raw material’s omnipresence in France. Companies outside France are also lining up to profit from the windfall.

Seville’s “Metropol Parasol” is built with LVL beams.
Par Frufaro - Travail personnel, CC BY-SA 3.

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