Wood supplies are changing for many US plywood mills and so it is for Boise Cascade’s Elgin, Oregon operation. It has another distinction in that it successfully produces 94% sheathing in the face of a general trend to steer away from that product in favour of specialised panels. Competition from OSB has fuelled that trend. The mill produces about 235 million ft2, 3⁄8in basis, annually.
Elgin is dipping its toe into pine, targeting 7in to 12in smalldiameter logs. Pine log prices are more reasonable and Elgin will substitute it for white fir, for inner plies and backs.
The mill has peeled mainly Douglas fir, white fir, and spruce. Region engineer Jared Rogers said: “White fir used to be considered a weed by our foresters, but we could use more of it today. The pine is left, so we’re going to find a use for it – at least for core, if not faces and backs. It frees up the white fir for our stud mill.”
The mill complex has a log utilisation centre for barking and bucking. The plywood and stud mills complement each other quite well, with oversize and undersize logs going for studs (2in x 4in vertical members for timber wall frames). “It gives us better recovery,said Mr Rogers. “We get the entire product out of the log. The bark goes to hog fuel, chips to our paper mill, and sawdust and shavings to our particleboard plant.”
The plywood plant has considerable steam needs for its dryers, presses, and hot water vats. It shares two 60,000lb/hour Keeler boilers with Boise’s adjoining stud mill which uses steam for its dry kilns.
The utilisation centre has Nicholson A5, 35in and A3, 27in, ring debarkers, along with six 6ft Boise-designed chop saws on each side. Either side can make veneer or stud blocks, depending on quality and straightness.
A 78in Black Clawson whole log chipperhandles lily pads (log ends) and scrap.
Blocks entering the plywood line are kicked into bins from where they either go to inventory or to nine hot water vats designed by Boise. Most of the stud logs move directly on chains into the stud mill.
The log centre runs on a five-day week, while the plywood mill runs seven days.
Pine peeling has resulted in log conditioning changes: Douglas fir and larch spend 10 to 12 hours in the vats to reach a core temperature of 120oF (49oC). However, 85oF (29oC) after two hours’ vat time does it for the pine, which lays flat with limited wrinkling as it advances through the mill.
Blocks proceed through a Coe 790 charger with x-y positioning and a Coe 1390 core drive for the Coe-controlled Premier VL50 8ft lathe, which peels a maximum diameter of 27in (69cm). It has a large roller bar and clipping trash gate.
Peeled veneer offbears to one of three 100ft primary trays and then progresses to the Ventek scanner and Raute clipper. Four Raute bins automatically stack 54s while 27s go to the green chain, as do strips on two strip trays from the clipper.
An Acrowood chipper handles the residues, while an inventory area stores veneer awaiting drying.
The plant has three steam-heated veneer dryers: A Raute three-zone, four-deck, 20- section jet dryer; a Coe two-zone, eightdeck, 20-section longitudinal dryer; and a Moore two-zone, six-deck, 16-section longitudinal dryer. The longitudinal dryers are both split-feed so two different items can be dried at the same time on each dryer.
The Raute jet dryer is a 1998 model which handles 54s only and is equipped with a Raute automatic feeder, unloader, and moisture detector and a Ventek automatic grade scanner, ahead of a Raute eight-bin automatic stacker.
The Coe dryer, which is over 30 years old but has been rebuilt twice, unloads through Elliot Bay brush moisture detectors. The bottom five decks process 54s, which transfer to a Raute eight-bin stacker, while the top three decks process random-width material, graded and sorted by hand.
Both of the eight-bin stackers have Raute automatic unloading systems.When a bin accumulates a full load it rolls out on to a cart to go to the forklift pick-up area.
The Moore dryer is 40 years old but has also been rebuilt twice. It is used to dry fishtail, random, or 54s as required. The most recent rebuild included a Grenzebach AKIdesigned insulated steel floor.
“It’s amazing how much heat that concrete used to suck up, because our production jumped significantly,said production manager Greg Howard.
All emissions from the three dryers are routed to a Pro-Environmental Inc thermal/ catalytic oxidiser, or TCO, installed in 2003; the unit destroys more than 95% of the VOCs coming from the dryers.
After dry inventory, the material moves over to the lay-up line, a Superior five-station installation employing foam glue in a SparTek system. This produced glue savings of more than 20%, according to Mr Rogers.
A Coe carousel stacker after lay-up accumulates the panels ready for pressing in one of the three press lines with a total of 90 openings. “There are normally no problems in getting the wood into a press before the glue can dry out,said Mr Rogers.
Globe pre-presses serve the three steamheated 4ft x 8ft presses: a Williams-White 30-opening,Williams-White 36-opening, and a Merritt 24-opening.
A Kimwood five-bin grade sorting line follows the presses, where panels are sized, graded, banded, and stencilled for shipment.
A Timesavers top sander does some touch work and a Globe tongue-and-groove machine processes occasional orders.
