Back End Help
By Jean Sorensen
One of the trickle down effects of handling increasing amounts of mountain pine beetle (MPB) logs is that BC’s Interior dimension lumber mills are seeing a growing number of boards landing in the back end with more, and more varied, defects. Even screening logs in the bush, optimizing in the front end, and enhanced edger optimization has not eliminated all the defects rushing by graders and auto-graders.
The mills’ challenge is not only dealing with greater volumes, as mills increase feed speed and get larger, and handling more defects. With vanishing margins, they must also ensure that every piece of lumber is graded just right, meeting grade rules without giving anything away or trimming off valuable wood.
Council of Forest Industries (COFI) representative Gary Crooks in Kelowna says that “We are getting more lower grades coming out of lower grade product because of the checking and defects”. Yet, Crooks said COFI, accredited by both the American Lumber Standards Committee and the Canadian Lumber Standards Accreditation Board, as well as the inspection arm of the National Lumber Grading Authority, is still seeing mills stay on grade and meeting international grade standards.
The 5% margin exists to accommodate the subjective nature of visual grading. “It’s there because of a difference of interpretation,” he says, but there is no doubt that graders today are dealing with more problems when making discretionary calls. Auto-grading is a way of gaining more insight into and control of bug-kill lumber, but as Crooks says “it’s not l00%” and some human input may still be required.
Beetle-based defects are also raising structural issues. Forintek’s Dr. Conroy Lum agrees mills are experiencing “some difficulties in applying the grade rules. There is a lot more lumber with cracks.” While it’s “a matter of getting used to it” he says, the greater predominance of MPB wood is changing the international perception of BC Interior wood. “Customers are saying that our wood looks different,” he says, adding that in essence, it does. Instead of milling and grading live wood, BC Interior mills are grading wood that is from dead or dying stems and the resulting lumber has the characteristics of the MPB infestation, namely stain and more checking. That in turn makes some wonder whether wood from dead trees has the same performance characteristics as that from green stems? And, are defects encountered in live wood milled the same as defects in dead wood?
As an example, Lum says that “The (current) grade rules limit the size and length of checks and where they might appear, but don’t limit the frequency,” he says. The board may still technically be on grade, but there may be a need to question whether the frequency of checking impacts structural integrity, points out Lum.
Lum’s research is attempting to ensure that those lumber grades that builders have associated with a structural strength level also apply to MPB wood. “Are we still comfortable with the design values (derived from testing on green timber) prior to the MPB?” he says. As a result, Lum has been working on an unusual project – a regional one funded by the MPB Initiative Fund – which has been sampling batches of graded MPB wood from Interior mills, and attempting to determine whether characteristics remain on grade. He is also developing a protocol for compensating or correcting for any discrepancy that may be found.
He realizes it is a challenging task, as integral lumber quality can change within geographic areas, and also by samplings. While grade rules are meant to be applied on a national level, Lum hopes to establish a protocol or guidance that agencies such as the NLGA can use to adapt current grading standards – if necessary – to regional or local mills dealing with what Lum calls a “natural” disaster, such as ice storms, fire, or bug infestation. Lum expects to present findings to the NLGA by late March. He may find there is no change in the structural integrity of the lumber despite more checks, and at that point it becomes a market issue between the mill and customer as to how they want to sort the wood.
Making Today’s Grade
In the meantime, sawmillers have to be able to get the most from MPB wood at the mill back end. COFI in December 2007 released an MPB report on the Interior of BC carried out by former deputy minister of forests Don Wright. The report estimates that lodgepole pine stands are 36% of the merchantable timber in BC’s Interior region. An estimated 80% of the pine in the Interior will be killed by the time the beetle runs its course by 2015, resulting in an average 30% of all BC Interior stands. In some areas that figure translates into 50% or more in the region. The report is recommending that harvest levels be kept high for as long as possible. Moreover, recent reports indicate that mills will be able to make lumber from this resource for much longer than originally assumed, perhaps for another decade or more (see box on page 17). In short, there’s money to be made at getting good at handling this stuff.
Coe Newnes McGehee is one supplier that has been attempting to bring more information together in an integrated optimization system that will deal with MPB-specific issues. CNM has developed the next generation of its Lineal High Grader (LHG), something it has been working on for the past three years. LHG’s auto-grading systems are not new, although most units sold up until the past few months are used mainly for geometric scanning. The new generation allows for the board to be looked at in many different ways, with that information relayed back to a computer where the collective information on the defects is evaluated for a truer picture of the board’s quality. It works very much like a folio system, with layers of information superimposed upon one another and then an evaluation made about the type and severity of the defect.
CNM’s optimization product line manager Chris Wells says his company calls the technology DataFusion. “Fusing data” is not a new concept. In fact, studies began in the US military decades ago when staff attempted to find ways of gaining more accurate information on foreign objects, such as aircraft or missiles by combining radar and thermal imagining. The concept has since evolved in medical research and industry in general.
In the wood manufacturing industry, there has been more of a focus on fusing data together in the primary breakdown stage than in the back-end of the mill. Some systems have also brought applications to stud mills, but dimensional lumber posed a greater challenge.
CNM’s DataFusion system uses four technologies:
- Laser profile sensing (triangulation for geometric data collections such as size, wane, skip, holes, crook, bow, twist, splits and shake).X-ray, which measures density and determines MSR/MEL and identifies rot, pith location, and knots.
- Vision (captures digital images of the board surface and identifies knot type, discolouration, small holes, stain, check, fine split/shake, rate of growth, machine surface defect and rot).
- Scatter and dot vector, off-shoots of the vision technology that uses the tracheid effect on the lumber’s surface to measure grain angle and identify blond knots, blue stain, slope of grain, grain distortion, and diving grain.
It’s an array of data that only today’s processing speed can handle, and while the LHG was designed as a modular system, allowing mills to start with the basic geometric system and then add other components later, Wells says mills today are simply starting off with the full visual package.
The beta test site for the full vision scanning LHG has been West Fraser’s Fraser Lake division in the central interior. A spokesman at the mill site says the prototype started approximately three years ago and has been “experimented with over a period of time”. The mill has two lines running, one with the upgraded LHG system and one with geometric scanning only.
“It does detect defects much more accurately,” he says, when grade and productivity figures are compared to the line without the system. However, he declined to reveal the percentage figures.
Despite the ability of the unit to work independently, West Fraser is using its system with manual graders. The advantage it has provided is picking out dry-lumber defects with greater accuracy. The spokesman said it would be much more difficult to stay on grade without the system, and errors in grading might occur, resulting in lost revenue.
“If we didn’t have it, there would be a change in the quality, and we would have to run slower than we have in the past. We are running at 160 boards a minute,” he says, which allows the manual graders the ability to inspect lumber yet over-ride an auto-grading decision. With the ability to see finer shake, rot and white spec, the system is really complementing the graders at the site, he feels.
Wells said the West Fraser system has been designed to deal with bug-killed wood, yet other systems where bug kill lumber is not a problem are using the same algorithms to grade dimensional lumber up to 3,000 fpm a minute. Two systems in Europe are actually running at 3,300 fpm, and in all cases mills can choose to eliminate, complement, or reduce graders. “We leave that up to the mill to decide,” he says, although he acknowledges that the range and volume of defects in mills with a heavy dead wood diet can make it tough to do without at least one check grader. Auto-graders have become one of the fast growth sectors of technology for companies such as CNM. The reason, says Wells, is their ability to provide a fast pay-back on investment. That can be achieved through a combination of labour cost reductions, increased product recovery (reducing trim loss) and grade recovery, and increased throughput and grade recovery (above grade especially).
One of the system’s strengths is its ability to deal with defects within defects, such as shake in wane. “The system has been able to see the fine shake in the stained wood, and very accurately track it into the wane and through the eased edge,” he says. Defects within wane and eased edges, he says, have always been a challenge to optimized systems, but by having more information through an integrated LHG system, a better grading decision can be made.
Currently there are 13 visual grading systems sold or installed worldwide; four in Canada, one in Australia, and the rest is in the US, where larger companies such as Weyerhaeuser have embraced the technology. In Canada, WF’s Fraser Lake has the beta model, one has gone to a Fraser Papers sawmill in New Brunswick that deals with a lot of balsam fir and rot issues, and two more are slated to go to West Fraser’s Quesnel operation. The company has also done LHG grade testing at its facility in Salmon Arm, BC for such major MPB players as Canfor and Tolko, with favourable results.
“My assessment is that the system has reached the level where you could use it to grade dead MPB lumber,” concludes Barry Harley, planer manufacturing control and special products coordinator at Tolko’s state-of-the-art Quest Wood Division. “This system would allow us to start cutting-in-two for grade recovery again.”
All good, as provincial figures for the Quesnel Timber Supply area identify it as one of the hardest hit areas, with 1.2 million ha of the 1.6 million ha area infested. Natural Resources Canada also cites the Quesnel area as having the largest change in fibre and revenue in the Interior because of the MPB over the next decade. With big volumes, and years to go, gearing up for the beetle is paying off.
BC's gain...your pain?
A new study by the reliable International WOOD Markets Group predicts the BC Interior sawmilling sector will remain a major force in lumber markets for possibly another 10 years, despite recent gloom and doom scenarios. I reported a few months back on the BC government’s update on the beetle salvage efforts, and its two “bad” or “worse” scenarios for future harvest levels. Both predict 20% drops from the 2006 harvest level over the next five years, ending with either 45 or 55% total drops within 10 years. If you’re thinking similar drops in lumber production, think again.
The discrepancy centres around the economic shelf life of beetle kill timber, and BC Interior sawmills’ growing skill at processing it. “We have learned that the BC Interior forest industry has become very efficient at milling three- to five-year-old dead pine trees,” says Mike Jahraus, IWMG vice president. “Although grade recoveries have slipped, so far the industry has largely been able to battle the potentially devastating impacts on mill productivity and lumber recovery by strategic capital investments in new technology, changes to mill configurations, and enhancements to log processing in the woods.” That includes relaxing top diameter requirements and leaving more cull in the woods, but the end result is the same. Over the next five to six years, the BC Interior lumber output will remain roughly where it has been since 2004, or 13.5 to 15 billion bdft/yr. After that, it will trend down, ending at between eight and 10 billion bdft by 2020, the same very respectable levels the region reached in the late ’90s. And, the report notes, it could be higher for those first 10 years.
Good news for local sawmills and loggers; bad news for folks elsewhere hoping that BC’s pain would be their gain. It will, but not as soon, and not as much. – Scott Jamieson
This is the first in a series looking at how some BC Interior and Alberta operations are dealing with the beetle. Next issue we look at green end strategies.