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Canucks head to Florida—to help with sawmilling

Florida-based Suwannee Lumber needed to find a way to handle dense, heavy and pitchier Southern Yellow Pine through its sawmill. The solution? Bring in the Canucks, in the form of Bosch Rexroth Canada and its MAC-8 control system.

They may take up to six generations to mature, rise to a majestic 150 feet, and live for half a millennium, but to 21st Century U.S. lumber producers south of the Mason-Dixon Line and east of the Great Plains, pinus palustrus trees can be a pain.

We’re talking, of course, about Southern Yellow Pine, specifically Longleaf Pine, the granddaddy species of the pinus genus. Longleaf leads a family of 10 hard needled, resin-heavy relatively “hard” pines that eventually move into homes as durable, good looking floors, pressure-treated decking, paneling, siding, windows, doors and moldings.

That’s the positive part. The palustrus problem, however, is in production. Modern, competitive high-speed production.

For a sawmill looking to rapidly—and profitably—turn raw trees into finished lumber, the stuff can quite literally gum up the works. It’s the nature of the material to be harder, heavier, denser and pitchier than any other pine specie. It’s enough to give high speed sawmill operators and equipment manufacturers high anxiety.

Witness the recent story of Florida-based Suwannee Lumber Company, one of the leading Southern Yellow Pine, Longleaf Pine lumber producers in the U.S.

It’s the nature of Southern Yellow Pine to be harder, heavier, denser and pitchier than any other pine specie. It’s enough to give high speed sawmill operators and equipment manufacturers high anxiety.

In a move to increase efficiency with updated equipment, Suwannee decided to replace its ten-year-old Chip ‘n Saw line with a new HewSaw R200 PLUS, a state-of-the art, programmable logic controller-operated (PLC) packaged hydraulic sawmill. It’s a small-footprint, full log processor. “Pretty much a sawmill in a box,” is the way Suwannee maintenance director and assistant mill manger Wes Grant describes it.

Manufactured in Finland and marketed through HewSaw North America of British Columbia, the HewSaw R200 PLUS is a remarkably sophisticated machine. It’s engineered to process logs using a scan and set philosophy, with each individual log being scanned on a conveyor. That data is used by a Pro Logic+ Optimizer system to instantly develop a log profile, which is in turn sent to a motion controller. Cutting heads and saws are immediately positioned to manufacture the desired pattern of lumber from the log.

At the same time, and only trailing behind by a mere 14- to 16-feet, another log is fast on its way to becoming porch decking. Any possible change in pattern is precisely achieved in the time it takes the log to travel to the cutting heads. With a feed rate of 650 feet per minute, don’t blink if you want to see it happen.

Delivered from Finland to Florida in November 2008, Suwannee Lumber’s HewSaw R200 PLUS was designed to be fitted on-site with a hydraulic power unit, motor control centres and motion and logic controllers.

Two other integrators, both from Canada, supplied the optimizer, sequential logic controller and frequency drives. Bosch Rexroth Canada provided the hydraulic power unit from its fabrication shop in Welland, Ontario. The machine also arrived from The Land of a Thousand Lakes equipped with Bosch Rexroth proportional valves.

As anyone who’s ever done it can attest, commissioning sophisticated machines can be time consuming, and the HewSaw R200 PLUS is no exception. It’s a team effort, and there are literally hundreds of calibrations and settings that have to be completed and tested before the machine can run according to specs.

Twenty-two days after the old line was dismantled, the first log was run through the new HewSaw R200 PLUS.

Along the way, some challenges surfaced. Suwannee mill manager Chuck Morgan reports that from the get-go, the machine simply was not able to perform up to its capability. “We struggled with axis problems, inconsistency (of) movement and we had some hydraulic issues,” Morgan says.

The fundamental problem? It had to do with the wood the equipment was working with, rather than the equipment. Southern Yellow Pine and its inherent characteristics were apparently lining up to defeat the machine.

Relates Suwannee’s Grant: “This was the first location where the HewSaw machine was installed and running with Southern Yellow Pine.

“That species is much heavier, more dense and has a stickier gum than anything else that the machine is being used to cut. So, the Southern Yellow Pine handed the machine a plethora of problems that had to be overcome to run it.”

Rock Fournier is the project manager/sales for HewSaw. It’s his job to make sure customers are satisfied with his company’s products and, if they’re not, to find a way to fix the problem.

Some additional expertise was called in—HewSaw teamed up with Suwannee management to call in Bosch Rexroth Canada.

There are limitations to what electronic devices can do. Problems frequently occur when a device is being asked to perform tasks for which it was not designed.

Such was the case, Bosch Rexroth sawmill industry specialist Rodney Trail discovered, with HewSaw and Suwannee Lumber’s Southern Yellow Pine challenge. “If you have some external disturbances or there’s something going on with the wood, you can often have issues with the motion controllers. And the motion controller is the heartbeat of machine. You have a ‘brain’ at the top that’s telling the motion controller what to do, but if it can’t execute those requests properly, then the machine has to stop. And every time the machine stops, a company loses money,” Trail says.

Led by HewSaw, an international team from Bosch Rexroth, HewSaw, Pro Logic+ and Suwannee Lumber Company was assembled and was given tight deadlines to fix it and be back on line.

So positive were they that they had the solution, Bosch Rexroth even upped the ante by guaranteeing HewSaw in writing that its new MAC-8 control system would solve the oscillation concerns. That pledge immediately caught HewSaw’s attention.

“It was really interesting to us that Bosch Rexroth was willing and prepared to give us a written guarantee that its controller would work. What we stipulated to Bosch Rexroth was that we could not do any changes to the hydraulic system—it has to be the controller—and they did come through with their promise of stabilizing the axis,” says the team at HewSaw.

Proprietary Bosch Rexroth modeling software was used to accurately model all positioning axis on the HewSaw R200 PLUS, pinpointing the trouble areas and provided complex control structures aimed at not only controlling the axis on the machine, but providing exceptional position accuracy and motion profiles within 0.1 mm.

The Bosch Rexroth MAC-8 multi-axis motion control is engineered to handle the combination of a large number of axes that need to be controlled in real time and process-specific parameters.

“This machine has run since we installed it in June 2010, and it hasn’t exhibited one of the problems that Suwannee Lumber had before,” says Bosch Rexroth’s Trail. “The machine has run pretty much rock steady since then.”

Trail’s view is echoed by Suwannee’s mill manager Chuck Morgan. “As far as the movement and instability that we experienced before, it has been much better. It’s a night and day difference. With the Bosch Rexroth controller, it’s like having a whole entirely different machine. HewSaw and Bosch Rexroth worked around the clock and they were able to bring the machine on line. And once we started to come on line, the machine came up and was running.”

This story and photos were supplied by Bosch Rexroth Canada, the Canadian subsidiary of Bosch Rexroth AG, one of the world’s leading specialists in the field of drive and control technologies. For more information please visit:
www.boschrexroth.ca