Learning the latest at Oregon State University - Wood Based Panels International

Jim Reeb, OSU, symposium chairman, makes point in opening meeting

Learning the latest at Oregon State University

A group of western US and Canadian plywood management and production people gathered at OSU, Corvallis, Oregon, in June for the 37th annual manufacturing seminar to learn the latest and to study long-term trends. Bill Keil joined them and sent this report

Published: 07 November, 2005

Jim Funck showing wood samples

Chairman Jim Reeb of the sponsoring College of Forestry group welcomed the attendees and set them off on two days of instruction by a dozen US and Canadian university professors and industry suppliers.
Steve Zylkowski, quality services director of APA – The Engineered Wood Association, Tacoma,Washington led off by announcing record North American panel production last year. He declared, “All engineered wood products are doing very well in North America, and LVL [laminated veneer lumber] is probably the most robust. North America is the target for LVL exporters.”
He noted that skyrocketing oil prices are forcing resin prices upward, but other factors such as US housing starts are very positive for the panel market. After the record 2004, he expects housing starts to decline slightly until gaining over a two-year period, beginning in 2008.
China is much in the news, but Mr Zylkowski said Brazil has a much larger impact on softwood plywood. Chile is also important.When US prices rise, imports increase. Brazil is the main OSB exporter.
He said the new flood of OSB production will impact all sheathing prices, but he predicted that one-third of the announced mills “will not happen”. OSB’s share of the residential sheathing market is now 72% and is predicted to continue rising.
“The industrial market for plywood is the big one,” he declared. “We have significant needs that can’t be met with OSB.”
Moving to marketing, he strongly advised producers to learn what customers want and to educate the end-users.
Jyrki Pesonen, vision systems manager, Raute Group, New Westminster, BC, explained electronic vision veneer defect detectors and sorting methods employing linescan and matrix/area cameras.
“The higher the resolution, the better the results,” said Mr Pesonen. “And colour is much more helpful.”
Systems enable veneer clipping and grading simultaneously where green end laserbased sensors clip material based on the camera. In patching, a camera defines defects and determines how and where to patch. “The camera is consistent. There is always minor variation on the human side,” Mr Pesonen concluded.
Linear programming is the speciality of Steve Griffith, Optware Solutions, Beaverton, Oregon. He said: “You can quickly get into thousands of variables making it difficult to handle with spreadsheets and other methods.”
Typical of the many variables are log procurement, transporting logs to alternate mills, primary or secondary conversion, sawn lumber or making veneer.
Linear programming helps business product mix – assembling veneer in different ways, allocation/transportation, multiple mills blending multiple raw materials, and minimising manufacturing cost. On the timber side, scheduling timber harvest during the year, according to weather and environmental conditions, can be eased. Investment decisions such as maximising present value and cash flow are an important part.
Mr Griffith explained: “Once your business is modelled it can be optimised to reveal the best potential operating pattern.”
He said the Martco plywood mill in Chopin, Louisiana, has full plant detail. Each process and the entire plant are modelled. The company looks at it for product mixes, the single most important factor on the bottom line. Georgia-Pacific Corp, he said, optimises its orders to plan production for its 18 mills.
“Everything is tied to the price of oil,” warned Jim Wilson, professor emeritus, OSU, “and environmental policy is mandating emission control which can substantially increase use of natural gas and electricity,” [Editor’s note: oil prices passed US$60 per barrel at mid-year.]
He said the price range is enormous for fuel, depending on such factors as location and negotiations. It all boils down to the fact that energy plays an increasingly important role in production costs.
Emission controls can increase gas consumption by 150% and electricity costs by 30%, all without producing any more products. In plywood production, this additional load is principally in controlling emissions from dryers and boilers.
Professor Wilson had some tips to conserve energy:

Negotiate favourable energy rates: spot markets vs contracts
Maintain dryers
Sort sap/heart
Keep dryers full
Lap veneer
Control exhaust air
Don’t over-dry
Dry to higher moisture content
Sort re-dry for ‘room conditioning’
Use minimum press time
Cover log conditioning vats
Insulate vats or chests
Control water temperature.

Associate professor Charles Brunner presented an outline of wood anatomy and the wood structure elements that affect veneer. He said annual rings affect the figure and surface quality. Sapwood/heartwood affects colour and initial moisture content and spiral grain affects strength and splitting.
Associate professor Jim Funck said: “All of you are impacted by the dryer,” opening his session on drying veneer for quality plywood. He emphasised that drying energy requirements increase as moisture content decreases. He said green moisture contents vary by species. Softwoods vary a great deal by heartwood and sapwood, however hardwoods don’t vary as much. The season also affects moisture content.
The important control in the dryer is that of air flow, temperature and velocity. This is achieved by dampers, full loading, good seals and proper maintenance.
Veneer should be sorted ahead of the dryer for species, moisture content, and thickness; he indicated that denser wood with the same moisture content takes longer.
Shrinkage only begins with moisture removal beyond the fibre saturation point. Radial shrinkage is different to tangential. He said: “That’s why we lay up plywood in opposite directions, but LVL is designed to replace solid wood, so most is laid up in the same direction.”
Continuing the drying discussion, Tim Fisher, veneer plywood sales director, The Coe Manufacturing Co, Portland, Oregon, said veneer drying in the Southeast US mainly uses steam. Hot oil is emerging in some regions and hot water is employed to some extent in China and Southeast Asia. However there is a problem in achieving sufficiently high temperatures.
Most new dryers have floors with insulation, and very tight seals at door bases, with an open area under the dryer floor for longer life and easier maintenance.
Sheet overlapping, where the trailing and leading edges are crowded together, produces greater production.
He emphasised that the mass air flowing through the dryer, not the air velocity, dries the veneer. He said surface temperature of offbearing veneer should be about 120ºF for moisture metre accuracy and pieces should not overlap as they go through the meter.
Joe Karchesy, associate professor, explaining wood adhesion, said adhesives must wet the wood, flow over the surface, and transfer to the other surface. They must penetrate the wood two to three cells deep.
Dense woods are harder to glue and too much moisture causes problems. Veneer surface texture (rough surface can result in gluing voids) and surface chemical composition, such as oil spills, can also be problems.
Wally Rowland,Willamette Valley Co, Springfield, Oregon, said adhesive dry-out is the biggest problem. He said consistency in resin ingredients is quite important and wheat flour is the most important extender. Extenders not only improve the performance of the adhesive, but conserve resin.
Gary Remillard, Dynea, Eugene, Oregon, said that an almost infinite number of resins can be tailored for unique mill performance by varying formaldehyde/phenolic molar ratio, percent of non-volatile solids, catalyst type and percentages, molecular weight distribution, reaction procedure and additives.
For adhesive design he asks for information on conventional, intermediate, or high moisture content veneer drying practices; plant operating practices; product mix; log/veneer source; and bonding requirements.
His advice on adjustments for optimum gluing performance are: veneer temperature, glue spread, open assembly time, pre-press time, and hot pressing time/temperature.
In pressing, Mr Remillard discussed staged pressing with pressure reduced from 175psi and then down to 150psi and then ramp down to 50psi for the last 30 seconds. “It gives the pressure a chance to escape instead of blow,” he explained.

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