Troy Lumber is a second generation, family owned company that has been doing business in Troy, NC for 85 years. The facility is home to a sawmill and planer mill that processes Southern Yellow Pine into dimension lumber.

Troy Lumber recently completed a front-end mill renovation project that has improved its economic outlook with a 7-12% recovery increase.

The mill replaced an older four-sided canter line with a new primary line and a new USNR 12” Horizontal Shape Sawing (HSS) system with MillExpert scanning, optimization and controls. Allen Whitesell, Vice President of Production said, “This project changed our whole world.”

USNR provided a centering infeed, transfer deck, infeed module, horizontal shape chipper and a double arbor HSS. USNR also supplied a complete optimization package including the 3D Smart TriCam scanning and MillExpert™ cant optimization system, along with controls integration.

After seeing the HSS double arbor gang in operation at Culp Lumber and Bennett Forest Industries, the President of Troy Lumber, Fred Taylor Jr. said, "We were impressed with the piece count and the finish of the wood coming out of the USNR HSS machines. Then we toured 15 other mills in the South, and after seeing what everybody else had, we thought the HSS was the best machine on the market."

The mill bucks the logs and sorts by diameter. Big logs go to the carriage, which also uses USNR’s MillExpert optimization, and small logs go to the new primary line that feeds the HSS with two-sided cants. A reciprocating belt sends cants from the carriage to the HSS and boards in need of edging and trimming go to downstream machine centers.

Troy Lumber is seeing major benefits as a result of the project. “Our two and better grade percentage has increased dramatically,” Fred said and added, “Our trim loss has dropped dramatically, and the lumber dries straighter too.” The mill cuts a high percentage of prime lumber and tries hard to avoid making lumber with any wane at all.

	Fred stated, “We’re seeing more sideboards that are longer and cut with more accurate faces.” Allen agreed and said, “Yes, we’re pretty much getting what we want from our material with the HSS.”

Virtual Pivot Technology: better accuracy, less maintenance

USNR’s HSS machine uses the revolutionary "virtual pivot" technology that enables the gang to continuously vary its pivot axis based on cant curvature and thickness. Depending on the curvature of a cant, the optimal point of rotation varies. The virtual pivot technology allows the saws to track the curve more accurately.

The design of the HSS also significantly reduces maintenance. The sawbox and motors are mounted on a simple base, and the whole mass rides on air bearings. Linear positioners precisely locate and orient the sawbox assembly anywhere in space. Gone are all the pins, bearings, cam followers and tracks used on other machines that require heavy maintenance to control sawing accuracy.

“The lumber is very uniform,” Allen declared, “We can run more lumber through our planer mill because of the uniformity of the lumber we’re making in the sawmill now.”

Fred confirmed, “Our planer production has actually gone up because of the quality of lumber we’re sending to it.”

Troy Lumber is currently processing about 6,000 logs per 8-hour shift, making 2x4s through 2x12s, 4x4s and 1x6s. The HSS is designed to be able to accommodate larger cants, up to 30” in width. Troy Lumber processes a wide variety of cant sizes from 4” to 12” thick. The design of the machine allows them to reliably process 8’ cants.

“We cut some 8’ lengths, and we’ve made mistakes and sent 7’ pieces through the HSS,” Fred admitted, “and it did just fine.” The system is currently running an average of 14-15 cants a minute, and can peak up to 18.

The machine configuration allows for a dense array of press rolls to maintain a secure hold of the cants. Control of the piece is so critical to accurate curve sawing that USNR presets the press rolls to facilitate the process.

When a roll positions on a cant and determines its thickness, temposonic feedback is used to preset the downstream rolls just enough to hover a 1/4” above the cant. When the cant approaches, the roll only has to lower a fraction of an inch as opposed to its maximum up position, which takes significantly longer. Until the roll makes contact there is nothing holding the cant at that location.

Troy Lumber’s new HSS gang system uses a chipper and gang combination with USNR controls to synchronize the movements of the chip heads and the saws. This enables the system to automatically achieve maximum recovery at high feed rates. USNR’s unique horizontal shape chipper uses conical chip heads and the same articulating bearings employed by the HSS to pivot along the cant’s axis of curvature.

MillExpert Shape Sawing cant optimizer delivers results

Troy Lumber’s HSS system receives cants from the carriage and the sharp chain. When a two-sided cant is presented to the USNR horizontal shape chipper, the remaining two sides are chipped away before it enters the gang.

“When it comes to recovery, what you don’t chip off is as important as what you do,” said Bruce Johnson, USNR’s Project Manager for the job. The sophisticated MillExpert cant optimization software has the ability to examine over a million solution permutations based on log grade, true shape, and product geometric definitions including wane parameters, as well as real dollar values.

The software provides advanced curve sawing capabilities including surface feature recognition which allows cant characteristics such as width, length, taper and sweep to be used to classify user definable grades. Multiple grade zones are easily configured within the cant, allowing different products with different values, targets, and wane rules to be placed in specific areas of the cant.

The HSS is capable of deflections of greater than 4 inches in 16 feet with the optimizer controlling the maximum allowable curve depending on cant characteristics.  A variable timber pocket allows the machine to cut anything from a 3” to 8” timber with the optimizer having the flexibility to limit the amount of curve depending on the size of the timber.

Fred added, “It's three times better than what our acceptance test stated, and we’re well pleased with it.” He went on to explain, “I would say we get somewhere in the 7-12 % recovery range, and our grade percentage has gone up between 3-5%. Our trim loss has gone from around 4% trim loss at the planer to around 2%.”

Start-up target date was a bull’s eye

The project was installed and started up on a quick turnaround, purchased in mid-October with a start-up date of March 10. Fred remembers, “it was a time-sensitive project and hitting that start-up date was critical for us.”

“The USNR team was really organized and arrived onsite ready to make the system work,” said Fred. “I have a hard time finding anything bad to say about the way USNR handled this project.”

Another factor contributing to the success of the start-up is USNR’s ground-breaking PLC system based on distributed I/O. According to Chuck Van Horn, USNR Control Products Manager, “We have eliminated more than 90% of the traditional field wiring and reduced start-up costs with our factory-wired PLC control system.”

Machine segments are pre-wired at the USNR factory to remote I/O modules that are mounted directly on the equipment. This reduces customer electrical requirements and enables complete system pre-testing prior to shipping.

Allen said, “Some of the hurdles we had to jump through were not USNR’s, and it wasn’t their place to fix them. But USNR went out of their way to help, and that went a long way with us.”

Allen Whitesell is Vice President of Production and has worked at Troy Lumber for 20 years. Fred Taylor Jr. is the President of Troy Lumber and has worked at the mill since 1992. His father, Fred Taylor Sr. is the CEO and is also very integral to the daily operations.