Stimpson Mills Go to New Strapping Technology

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Successful implementation by Samuel Strapping Systems leads Simpson Timber to upgrade other mills.

TACOMA, Wash. — One of the Pacific Northwest’s oldest forest products companies is also one of America’s most progressive. Simpson Timber Company was founded in 1890 by Sol Simpson when he took 50 men and 12 horses into the woods to work. Today the company operates both the largest straight line production sawmill in existence and the largest single site production mill in the U.S.

The single line mill at Commencement Bay near Tacoma, Wash., which was put into full production in 2002, is a demonstration of Simpson’s commitment to improvement and the future as well as a monument to the quality of sawmill equipment that is available today.

Collin Edwards, finishing superintendent at the Commencement Bay mill, pointed to the important role that machinery and equipment manufacturers can play in the success of a high volume production mill. When Simpson began the Commencement Bay project, they called on Samuel Strapping Systems for advice on how they could plan the packaging end of this large volume mill. Samuel’s technical sales team was able to recommend a polyester conversion package for a brand new Signode steel strapping machine that Simpson had in storage. Using the reliable VK-30 strapping head, the machine was converted from steel to run high strength Samuel polyester strapping.

In a single line mill like the Commencement Bay plant, every piece of equipment has a vital part to play in the profitability of the overall operations, Collin said. “We cannot have down time anywhere in the mill and fully meet our goals, so we depend on manufacturers like Samuel Strapping and all the others supplying our plant to give us their best.”

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With production throughout the entire $50-70 million plant at stake, only the most reliable equipment could be placed in the mill to avoid costly down time. The VK-30 must reliably strap more than 1 million board feet of lumber per day into bundles that are ready to wrap and ship.

The Commencement Bay sawmill is located central to Puget Sound and to Washington’s great timber resources. It was one of the largest sawmill projects completed in the U.S. over the past decade and has solidified Simpson’s position as one of the world’s premier timber processing firms. Located on 73 acres, the 180,000-plus-square-foot mill replaced an old stud mill the company had operated on the site since purchasing it from Champion International in the mid-1980s. Capacity at the new plant exceeds 250 million board feet per year.

The Commencement Bay mill is located almost at the exact center of Washington’s great Douglas fir and hemlock forests. The plant is also at a transportation nexus so logs can be brought in by truck or rail or floated in via log raft. Logs from northern Puget Sound locations or from the famed forests of the Olympic Peninsula arrive by raft and truck while those from the Cascade Mountains to the east or the coastal ranges to the south come by truck.

The logs are dewatered if necessary, merchandised, and then prepared for milling. An 850-foot-long, 35 ton P&H crane with a 330-foot span is the workhorse in the yard, stacking logs in decks up to 50 feet high.

When scheduled for breakdown, logs are delivered to a bucking line deck. They are singulated by a Linden quad feeder and moved to a 27-inch Nicholson debarker. After the bark has been removed, the logs pass to a Porter Engineering scanning system and bucking optimizer. The decisions made by the optimizer control the operation of a Stolberg Engineering dual-line circular saw bucking system.

From the bucking station logs move to canter line infeed decks; they are sorted based on the likely center cant yield of the stem. Logs with projected center cants of 4, 6 or 8 inches travel down one canter deck while those projected to yield 10 to 12 inch center cants are forwarded to a second deck. By varying the deck supplying logs to the breakdown centers at any particular time, the canter deck operator can control the flow of logs through the mill. If the operator sees a bottleneck developing, smaller logs likely to produce fewer jacket boards can be fed into the system until it is relieved, then larger logs can be reintroduced as capacity is available.

As the logs are fed down the canter line, they are scanned for orientation, rotated as they are conveyed, clamped in place and scanned again. The logs are then sent through USNR chipping heads and onto a USNR 6-foot high strain band saw. Line speed can vary from 250 feet per minute on large logs with sawing solutions to 550 feet per minute on small logs with chipping-only solutions determined by the scanners.

Sideboards from the band mill go to a USNR three saw optimized edger while cants go to a 12-inch double-arbor Hi-Tech/Comact curve gang saw system. Lumber exiting the gang goes to a trimmer and then to a 52 bin Hi-Tech sorter. Stacking is accomplished by means of a Gillingham Best unit.

The Commencement Bay mill produces green and dry lumber. For drying operations the mill is equipped with six double-track USNR dry kilns. Two 120-foot units, two 108-foot units, and two 80-foot kilns provide combined drying capacity of 1.3 to 1.5 million board feet, depending on the lumber. The shorter kilns are used for lumber produced in smaller quantities so that lumber does not have to sit green while an adequate volume is accumulated to fill a kiln.

Once dried, lumber goes to the planing center. It is processed on a USNR planer that has a production speed capacity of 2,000 linear feet per minute. The planer outfeeds to two 20-foot slow-down belts. The lumber is then graded on a three-person grading table. The graders inspect the lumber for defects while a USNR trimmer-scanner and optimizer scan the lumber for trimming.

After the wood is grade stamped, the green lumber is routed to a TDS Technologies anti-stain spray booth. Finally, the lumber goes to a 42 bin Hi-Tech sorter and Hi-Tech stacking system. The Samuel Strapping Systems VK-30 bands the lumber with high strength ¾-inch polyester strapping before it goes to a Gemofor automatic wrapping machine.

With the high-speed, high-volume operations, problems with any single process, even a simple one, can cause bottlenecks and significantly impact mill throughput. The strapping process is one example. “We average 325 loads per day per shift with more than 1 million board feet passing through,” noted Collin. “Any extended down time can be felt all the way back through the mill.”

The single Samuel Strapping Systems VK-30 head has easily been up to the job required of it, he said. Strapping green packs of lumber stacked 16 high or dry packs at 21 high, the machine has provided 97-98% up time while strapping up to1.4 million board feet daily. The reliability is a tribute to the quality of the machine and the support from Samuel Strapping, said Collin.

“We had not had a lot of experience, especially with polyester banding, prior to the building of this mill,” Collin said, “but the machine has proven to be very user friendly. The Samuel Strapping people have been great about providing the support we’ve needed to get up to speed, and our own people have done a very good job of learning what has to be done to keep machinery like this running efficiently, and then making sure it does run well.”

The strapping system chosen by the mill engineers has provided other benefits, too. The system supplied by Samuel Strapping is set up to use polyester strapping, and Collin considers polyester a huge advance over steel or galvanized metal bands that mills use for strapping lumber. The polyester is safer, costs less, and improves quality, he said.

Safety is a paramount concern at the Commencement Bay mill, according to Collin. “We stress safety above all else here,” he said, and that is one reason why the company uses 3/4-inch polyester strapping instead of 5/8-inch. Since the mill is highly automated and operates at high production speeds, there is little visual contact at the finishing end once the lumber is strapped and moves on to packaging. The additional strength of the 3/4-inch banding provides an extra margin of safety. Plastic is safer for employees all around, according to Collin. “You’re always seeing cuts, even through heavy gloves, with steel,” he said. “Plastic banding has not presented that problem.”

Polyester strapping has another advantage in the humid climate of the Pacific Northwest, Collin noted. Polyester bands do not rust and stain lumber. The company has experience with steel banding, and it may rust and discolor finished bundles. “You don’t see that with polyester,” said Collin. Polyester banding material also is easy to handle and cost-effective compared to steel, he noted.

Perhaps the greatest compliment you can pay a machine is that it does its job so well that other mills use it, too. That has been the case with Samuel Strapping Systems. A few dozen miles away from Tacoma, Simpson Timber Company’s Shelton operation is the largest single site lumber mill in the U.S. Based on the success of the strapping system at the Commencement Bay mill, both of Simpson’s Shelton plants were recently retrofitted with the VK-30 strapping heads.

“The conversions were done over a weekend and went extremely well,” said Shelton finishing plant superintendent Bob Miller. “We’re pleased with the safety and cost benefits and have been very pleased with the service we’ve received from Samuel Strapping Systems.”

Few companies are able to survive as long as Simpson without a strong commitment to the future and improvement — in lumber products, safety, efficiency, and other areas. At Commencement Bay and Shelton, Simpson has made a considerable investment in improvement and in the future. Its commitment and investment have spurred the development of two of the world’s premier lumber production facilities. The mills make a strong impact on the region’s economy and are setting standards for conservation, production and safety.