Big gains in cant throughput realized after two upgrades to curve-sawing gang.
URBANA, Arkansas—Curve-sawing methodsfor cants have been circulating in concept since the middle of the lastcentury. They began to take hold in the 1990s in softwood sawmills. Acurve-sawing gang guided by scanning and optimization technology can recoup themaximum number of the longest boards recoverable from each cant. As such, curvesawing delivers higher production and increases the value of that production byefficiently using every bit of fiber to create longer boards.
Ofcourse, sawmill managers and engineers look at a highly efficient curve sawinggang machine and see opportunities to make it even more efficient. That’s whathappened recently when one mill manager and some engineers got together anddeveloped a plan to improve the operation of an existing USNR Gen I McGeheecurve sawing gang.
StephenMurphy is the Manager for Sawmill Operations at the Urbana, Ark. facility ofAnthony Forest Products Company, a totally integrated forest products firm thattraces its longest root to the year 1916. Murphy collaborated with engineers fromUSNR via Jim Huffstatler, an account manager at USNR.
AnthonyForest Products Company is headquartered in El Dorado, Ark. USNR isheadquartered in Woodland, Wash.
Themill Murphy manages has been using optimizing technology since 1992. The“merchandiser” area got the transition started, he explained. “The trimmer andcarriage optimization were first, followed by the edger. Every machine centeris optimized.”
TheNewnes-McGehee curve sawing gang was installed at Anthony Forest’s Urbana millin April 1998. In 2009, the optimization system was updated, and the PLC5controls that were in place were retained. The older controls were fine, saidMurphy.
Evenso, Murphy had long had ControlLogix from USNR on his wish list. “We upgradedthe controls to ControlLogix early this year as part of a major mill makeover,”said Murphy.
Upgradingto ControlLogix was one of two major changes USNR made to the curve sawing gangat the Urbana sawmill in 2013. The other change was the addition offlare-reducing heads.
Thegoal of the upgrade project was to increase throughput. Flare reducing chipheads were added in front of the gang enabling it to process material faster bypre-chipping the excess fiber so the cants could run through the system at ahigher feed rate.
Minormodifications were made to accommodate the flare reducing chip heads. Thescanner belt was changed to a chain conveyor with overhead press rolls for morecontrol, and the existing infeed module was modified to extend the chainthrough the new flare reducing chip heads.
USNRworked closely with Anthony Forest to ensure that any existing parts that couldbe used in the new gang configuration were identified, retained and repurposed.In fact, said Murphy, USNR has shown much attention to helping his mill dothings in the most budget-conscious way.
USNRdesigned the mechanical conversion in a very cost effective manner to keep thecosts down so the mill could do the ControlLogix upgrade at the same time.
Afterreaping the benefits of the installation, Murphy said he wishes he hadinstalled ControlLogix during the 2009 upgrade. The results of the two gangupgrades, flare reducing chip heads and ControlLogix provided by USNR, areeverything Murphy anticipated they would be. “The flare reducing chip heads andoverhead press roll system allow us to speed up the gang,” he said. “Itshortens the distance between cants and increases the amount of sawing time.”
Cantsfed to the gang have a 4-inch to 12-inch thickness range. “Sixty percent of thecants are eight inches or wider,” said Murphy.
“We runa pretty high volume of large logs,” said Murphy. “On a very large cant –12-inch, we were sawing 125 linear feet per minute. The new speed on 12-inchcants has increased to 160 linear feet per minute.” That pickup in throughput is approximately 28percent.
TheAnthony Forest mill at Urbana saws all Southern Yellow Pine (SYP). It producesprimarily dimension lumber that ranges from 2×4 to 2×12.
Thegang at the Urbana mill operates five days per week on a 12-hour shift. “Weshut down for an hour at lunch and change guides and saws,” said Murphy.
Installationof the 2013 upgrades was quite smooth. “It was about a five-day turnaround,”Murphy said. “USNR representatives weregreat.”
“One ofthe least painful parts of the program” was completing the two upgradesprovided by USNR to the gang, said Murphy. “You have to understand that we hadextensive [work going on].” In short, the five days of mill overhaulencompassed significantly more than the work by USNR.
AnthonyForest has relied on USNR for decades, said Murphy. “My sales representative isJim Huffstatler,” said Murphy. “I would consider Jim a friend. I’ve enjoyedworking with him.”
TheUrbana mill produces more than 100 million board feet of kiln-dried,grade-marked SYP lumber each year. It does custom pulls for laminating stockand scaffold-grade lumber, and in the near future for machine stress ratedlumber.
Notonly does curve sawing allow for recovery of longer boards, but it alsoproduces more of the higher grades of SYP lumber. Slope of grain is onecritical criterion used by graders when assigning SYP lumber to a gradedcategory. That slope emerges beautifully from the curve sawing.
Leadersof Anthony Forest today are fourth-generation members of the Anthony group thatgot the company started as a various mill partnership across Arkansas,Louisiana, and Texas, almost 100 years ago. The company subscribes toSustainable Forestry Initiative (SFI) practices.
Inaddition to its commitment to environmental stewardship, Anthony Forest trainsits 250 employees to focus on a company mission that includes ensuring customersatisfaction, making safe practices the standard for operations, ongoinginvolvement in the community, leading in forest industry best practices, andreturning a profit to family shareholders.
TheUrbana, Ark. sawmill is one of several facilities Anthony Forest Productsoperates. Rounding out the company holdings are two wood chip mills (PlainDealing, La. and Troup, Texas) and two wood-laminating plants (El Dorado, Ark.and Washington, Ga.). Anthony Forest operates and jointly owns with EACOMTimber Corporation of Montreal an I-Joist manufacturing plant (Sault Ste.Marie, Ontario, Canada).
The ElDorado, Ark. headquarters city for Anthony Forest Products is the county seatof Union County. Urbana is in the same county and some fifteen miles east of ElDorado. The county itself is located in the south-central part of the state,near the border between Arkansas and Louisiana. El Dorado, which has apopulation of 23,000, grew as the center of the Arkansas oil industry inArkasas.
Murphyhas been with Anthony Forest for 25 years; and he is a stockholder in thecompany that incorporated the family partnership in 1965. His grandfather, whowas an Anthony family member, nudged Murphy in a direction that led to forestproducts.
“I wasa fishing guide in Texas,” said Murphy. “My grandfather told me it was time toget a real job.”
Murphystudied and became a certified grader at the school run by the NationalHardwood Lumber Association in Memphis, Tenn. And, he began his tenure atAnthony Forest as a hardwood grader. When the mill transitioned exclusively toSYP, he started working in the mill.
There’sa lot to like about the course he has taken, said Murphy. He enjoys “theinteraction with people.” And, he relishes the “challenge of increasingthroughput at the mill.” In his view, there is always a way to be moreproductive and more efficient. In that overarching philosophy, he has a goodvendor partner in USNR.
WhenMurphy gets some free time, his interests are quite definite. “I enjoy huntingand fishing,” he said. “I enjoy spending time with my family.”
Conversions toImprove the Accuracy and Safety of Curve Sawing Gangs:
Time-SavingPantograph Arm Conversion
Engineersat USNR consider every possible way to bring improvements in production andefficiency to their customers. Increasing throughput, the result at the Urbana,Ark. sawmill of Anthony Forest Products Company, is one method. Reducingdowntime required for maintenance is another.
USNRnow offers a conversion to pantograph arms that can cut considerable time fromroutine belt changes. For example, required belt changes on a McGehee gang cantake as long as two hours. But pantograph arms can now be converted to aconfiguration that reduces the frequency of required belt changes – in partbecause the new wider and polychain belts are 39 percent stronger.
It’snot just the longevity of the belts that contribute to a reduction in downtime.The conversion of the pantograph arms is usually done in tandem with a pivotmotor base conversion. Added to the drive base, an eccentric pivot shaft allowsa belt change to be done faster. And when new belt guards are part of thepantograph arm conversion, access is improved. Accessibility shortensbelt-change time. It also enhances safety.
Safety-ImprovingDuplex Air Cylinder Conversion
Indeed,safety is always on the minds of USNR engineers. Making throughput both fasterand safer strikes exactly the right note. And it’s a note sounded by the duplexair cylinder conversion that USNR now offers.
Holdingdown cants as they pass through a traditional curve-sawing gang — andexperience the lifting force created by the saws, requires quite a powerfuldownward force. Balancing that downward force — so that small cants are notcrushed and other cants do not get stuck or thrown — is a challenge that theduplex air cylinder conversion meets.
The duplex aircylinder conversion positions a larger bore cylinder above a smaller borecylinder. The stacked (multi-bore duplex) air cylinders for the press rollsallows greater force to be applied to larger cants and lesser force to beapplied to smaller cants. Hence, there are fewer incidents of stuck, crushed orairborne cants. USNR has installed a number of these conversions on manydifferent brands of gangs, all with good results.
Accuracy Boosting ElectronicSaw Offset Adjustment
TheElectronic Top Saw adjustment is a conversion for double arbor curve sawinggangs that provides on the fly electronic adjustment of the top saws relativeto the bottom saws for saw offset. The conversion consists of mounting a linearpositioner cylinder to the top guide bar so you can electronically adjust forsaw offset on a double arbor machine without having to shut down and lock themachine out to mechanically adjust the guide bar using wrenches.