With Machine Stress Rating

North American lumber mills are all too aware of the pressing need to optimize premium raw materials as much as possible. If a company is not maximizing the profit level of its lumber, it’s not making efficient use of its material resources.

Lignum Ltd., a Canadian sawmill, was grading lumber visually in the early 80s, an unfortunately inefficient method which prevented them from maximizing their profits on their precious resource. Because most of their lumber was sold as normal visual grades, they lost millions of dollars of potential returns every year.

Located in Williams Lake, British Columbia, Lignum is a privately owned, 35-acre sawmill with 250 employees on site and 40 more at its administrative office in Vancouver. The company has been in business since 1946, and now has the highest production output of any independent mill in North America, about 250 million bd. ft. of dimension lumber per year, a construction grade SPF (spruce-pine-fir) cut in 2" widths, from 2 x 3s to 2 x 10s.

Back in the early 80s, the company’s Vice President of Operations began looking for a way to add extra value to their products. After hearing about lumber testing machinery, he attended the Portland Sawmill Convention in Oregon to investigate.

The VP decided that producing MSR (Machine Stress Rated) lumber was the answer to the company’s goal of increased profit. Consequently, Lignum purchased a Model 7100 Continuous Lumber Tester testing machine manufactured by Metriguard of Pullman, Washington, a company specializing in MSR, physical testing, and lumber grading equipment.

The Model 7100 measures the effect of grain angle via the direct measurement of lumber stiffness in MSR, MEL or E-rated lam grades. Running at the same speed as the planing line, the high-production machine rates dimension lumber through a rolling stiffness test.

As the lumber rolls under the first test span, it is first deflected downward, then bent upward to a prescribed deflection by the next test span. Weak pieces of wood broken during testing are removed from the production process, thereby preventing this substandard material from reaching clients.

If a piece of lumber passes the testing, the MSR label is sprayed on as it leaves the machine. Obtaining an MSR involves mechanical testing, visual evaluation to determine piece grade, and daily quality control tests to verify the strength and stiffness properties of the final product.

Lignum’s lumber tester immediately began increasing their profit margin. Prior to purchasing the machine, only a small percentage of their high-grade lumber could be sold for high-end uses. Since that time the company has sold 80 to 90% of its total volume as roof truss lumber for residential and light industrial applications.

"Before we purchased our lumber testing machine, we weren’t getting full value for our product," stated Barry McKinney, Quality Control Superintendent at Lignum. "There was no way to prove we sold good lumber using visual analysis alone.

"We’re now able to take full advantage of our high-quality wood," he explains. "Now most of our product commands a premium price in the marketplace. The testing machine enables us to demonstrate consistent quality."

MSR lumber products improved profits for Lignum by increasing grade recovery while reducing material waste. The company’s truss-grade products are attractive to building contractors because they form stronger roofs and floors.

"We still do visual testing with three QC checkers after the wood comes out of the testing machine, but now the visual testers only have to check for knots and other easily- observed irregularities," McKinney stated. "So their work can be more focused on detecting flaws, since the 7100 has already tested for strength."

The truss building business is growing, McKinney says, since most homes and businesses built on-site now use roof trusses constructed off-site by truss plants.

"With visually-graded lumber, you might use about 40 roof trusses on a normal house, but with MSR lumber you only need about 35 trusses because it’s so much stronger,’ McKinney said. "Even though the MSR lumber costs more for builders, there is a great savings in the volume of material needed and in reduced labor costs to install them. Builders may spend an extra 10% more on the cost of MSR lumber, but they will save 15 - 20% in overall material and labor costs."

During the last ten years, Lignum has been able to recover about 35 - 50% of their narrow-width product as MSR grade.

"Our total MSR lumber output works out to about 40 to 45 million bd. ft. per year," McKinney said. "In our larger widths, our MSR volume is about 25 - 30% of our total volume most years. MSR commands about $65 per thousand bd. ft. over visual grades, which has been fairly consistent over the last seven to eight years. As a result, using the lumber tester has added millions of dollars per year to our profit margin."

Even though Lignum has limited space in their plant, they plan on purchasing another Metriguard lumber tester within the next two years.

"We’ve had such success with our existing machine, we’re planning on expanding our mechanical testing capability," said McKinney. "We think that it’s the best machine available for producing MSR lumber, and I would recommend their equipment to other mills that want to guarantee quality."

For more information on lumber testing equipment contact Metriguard at 2465 NE Hopkins Court, Pullman, WA 99163; phone: (509) 332-7526; fax: (509) 332-0485; email: sales@metriguard.com.