Weyerhaeuser has invested $24 million in recent years to re-work the green end of its OSB plant in Edson, Alberta, part of a continuous improvement program that has delivered resultsin the form of increased OSB production.
By Tony Kryzanowski
A $24-million investment by Weyerhaeuser over the past several years to replace the green line at its OSB plant in Edson, Alberta is part of a continuous improvement program at the mill. This ongoing program has resulted in the plant producing nearly double the amount of OSB compared to its original design when the mill opened in 1983. The plant now has rated annual production capacity of 440 million square feet of OSB on a 3/8ths inch basis, compared to the original design production of about 230 million square feet.
The latest capital investment included a building addition, installation of two Carmanah stranders and a variety of conveying systems provided by Tri-Tech Machine Ltd. Weyerhaeuser handled the engineering services for the project while the prime contractor was Eugene Forest Systems.
“All of the money was spent on the green end of the plant,” says plant manager Mitch Gregoire. A good deal of the money went to replace old strander technology from the early 1980s. “One of our new stranders is almost as productive as two of our older standers.”
Gregoire says Weyerhaeuser was able to build the addition and install the new stranders and conveyance system while the older green line continued to feed the plant. A wall was literally knocked out to connect the new green line with the existing plant, and the new line was integrated without any major disruption in production.
Like so many other OSB plants, Weyerhaeuser’s Edson facility is riding out a down cycle, with reduced OSB demand due to the reduction of housing starts in the United States. Gregoire says the Edson facility produces flooring and sheathing and a significant portion of its production is exported to the United States.
Historically, the State of California alone has housing starts equal to or more than all of Canada, noted Gregoire, explaining why the US market has such an impact on Canadian OSB manufacturers.
Gregoire says there are several reasons why the Edson OSB plant has become so much more productive over its lifetime, including improvements in both production techniques as well as materials, such as resins. Weyerhaeuser has also worked hard over the years to overcome whatever production bottlenecks may have existed in the system, which has had a further positive impact on overall production.
Handling and conditioning of logs has improved operations. Wood arriving in the yard has been merchandized to eight-foot lengths in the bush. Typically during the winter log haul, loads from arriving log trucks are fed directly into the conditioning ponds at the infeed using Komatsu PC400 log loaders equipped with Weldco-Beales short-wood grapples.
Once properly conditioned, logs proceed to the green line where they encounter two Nicholson debarkers and the new Carmanah stranders that create the strands used in OSB production. The strands are dried using three triple-pass MEC dryers before being placed in storage bins. Before the strands are dropped from the storage bins and placed on the Schenck forming line, they are mixed with resin. Their placement, or orientation, on the forming line mat depends on whether they will end up as the surface or core of the OSB panel, and the amount of raw material and resin is determined by the panel thickness.
The Dieffenbacher press has a series of openings like a baker’s oven, which are filled in sequence with specific lengths of mat material from the forming line. Once filled, the press clamps down on the strand/resin mixture in each opening using heat and a specified cycle time to produce raw OSB panels.
When the cycle is complete, the OSB panels exit the press on a conveyor and proceed through a Globe trim saw line that creates the four-foot by eight-foot OSB panels. The panels are stacked, strapped, packed and then allowed to cure in the warehouse for about 24 hours. Samples of the product are tested on a regular basis to ensure that they meet the required performance standards for building construction applications. Weyerhaeuser’s Edson facility employs about 150 people to meet its round-theclock operating schedule.
Earlier this year, Weyerhaeuser announced reduced operations at three of its OSB mills, including the facility in Drayton Valley, Alberta as part of a strategy to align its production with current demand. According to Weyerhaeuser’s 2005 Investor Guide, the company has capacity to produce about 4.3 billion square feet of OSB per year. The curtailed production at the three plants, the others being in Hudson Bay, Saskatchewan and Sutton, West Virginia, could reduce overall production by between 500 million and 600 million square feet on an annual basis.
A successfuland quickchipper install at Weyerhaeuser with 3D modeling
Last September, the Weyerhaeuser sawmill in Drayton Valley, Alberta, was given a last-minute opportunity to replace the main mill chipperbut it had to be done by year end.
The intake of the old CAE 55- inch chipper, installed shortly after the original mill was built, could not handle the flow of trim blocks from the sawmill and planer mill, resulting in multiple jam-ups per shift. The blocks had to be diverted to the refuse systemthereby losing chip revenue for the mill and adding the daily cost of labour to clear the blocked intake.
The feasibility study was given to McGregor Consulting of Spruce Grove, Albertathe contract project managers for the plantwith the following demanding scope criteria:
• The new chipper had to have a capacity large enough to handle all of the trim blocks produced by both the sawmill and the planer mill.
• The existing infeed vibrating conveyor had to be replaced by a larger conveyor with a wider intake.
• The new equipment had to be specified, ordered, delivered, installed and commissioned before the end of 2006 in order to get project approval.
The first challenge was delivery: Could a left-handed chipper be delivered to the site by December 21 at the latest? Carmanah Design (formerly CAE) said it would be “impossible.” However, the supply of a right handed chipper was just “nearly impossible.”
The second challenge was would the larger chipper fit into the extremely restricted area that the old chipper occupied? Rough measurements from the Carmanah drawing delivered the same answer: “nearly impossible.” As space restrictions were severe, McGregor Consulting decided to make a 3D computer model of the area, including all the existing equipment, and to position a 3D model of the chipper inside the model.
The model revealed that the motor support frame would not fit with the existing refuse conveyor Carmanah agreed to lift the frame to clear. It also revealed that the chipper lid, in the open position, would not fit with the “Superflow” conveyor above itCarmanah agreed to alter the lid to clear.
The vibrating conveyor posed the next problem as the existing conveyor had a downward slope of about five degrees from its infeed to the chipper infeed, with a concrete footing that went under floor level at the chipper end. As the company had never seen or heard of a sloping vibe conveyor, McGregor Consulting decided not to copy it with the new one. Due to height limitations they decided on a “balanced” vibrating conveyor from Edem that does not require a concrete base and can be anchored to the floor.
“The biggest problem, however, was that the existing chipper had a left-hand feed and the new one had a right hand feed.” explained Alan McGregor vice-president, design, of McGregor Consulting. “That meant the new chipper had to sit at approx. 90 degrees to the existing rectangular foundationdirectly across the old foundation width.” The question was: Should concrete be added to the base? McGregor concluded that was a non-startera sixfoot deep excavation in the area was impossible given the allotted shutdown duration. Another call to Carmanah revealed that the company had actually replaced 55-inch chippers with 65-inch chippers using the same concrete bases.
However, they had never switched a 55-inch left to a 65- inch right on the same base. McGregor Consulting went back to the 3D model for another look. They could pick up about 75 per cent of the footing area. They also found that the chipper had to be raised 8-3/4-inch to match the chipper bed plate with the bottom of the vibe trough. They then designed an adapter structure that was held down by all (seven) of the existing anchor bolts and supported the overhanging parts of the new chipper base. The upshot? The new chipper replacement project was completed ahead of schedule and under budget, says company president Davis McGregor. “What started out as nearly impossible turned out to be relatively easy after first being completely assembled in 3D cyberspace in our computers,” McGregor says.