Accurate, consistent automated grading with USNR’s THG
Vision scanning improves grade outturn, throughput
DELTIC TIMBER was looking to update its combination geometric and manual grading line with a state-of-the-art automated one. Automated grading systems offer consistent accuracy, and they operate at high speed board after board, shift after shift, day after day. THG was chosen for its suitability to the mill’s process, and the strong trust developed between customer and vendor.
Deltic Timber, headquartered in El Dorado, Arkansas, owns two stateof-the-art sawmills in the region at
Ola and Waldo. Combined annual permitted capacity for these two operations is in the range of 450 mmbf with approximately 200 mmbf recently produced at the Waldo facility with 150 employees. The Deltic
Timber mills produce 2x4 through 2x12 dimension lumber, timbers, and specialty products including MSR lumber, exclusively from Southern Yellow Pine.
The Waldo operation processes both small and larger logs, and includes a sawmill, boilers, dry kilns and planer mill. It recently upgraded its planer mill line with USNR’s Transverse
High Grader (THG) system, taking the lumber grading process from a largely manual one to an optimized line.
Investing for success
Tommy Downs, Waldo mill manager, commented on the reason Deltic decided to invest in this new process. “We were looking to improve the consistency in both throughput and grade determination, and better control our trimming. We also wanted to remove the manual element and reduce human error.”
Tommy explained that the mill had previously had another vendor’s scanner on the line for geometric scanning only. This meant they still required a significant number of manual graders for the visual grading component, and were experiencing difficulty at the planer mill keeping up with all of the output from the sawmill. The management considered other vendors, but selected the THG because of its better fit for the layout of the mill, and the good relationship Deltic and USNR have built over the years.
The new line
The new grading line includes a Revolver Lug Loader, THG scanning and optimization system, Grade Projectors, Grade Mark Reader and Multi-Track Fence. The mill’s strength predicting machine is positioned at the outfeed of the USNR high speed planer (installed in 2007), and sprays a mark on each piece it determines is a candidate for MSR. As the piece is scanned by the THG, it visually evaluates the piece for all grade characteristics while considering the strength prediction.
The THG then makes a grade decision having considered defects such as knots, wane, skip, splits and shakes.
The THG’s grade classification is assisted by a sensor positioned at the lumber line end of the scan frame – the pith sensor. This pith sensor visually measures the end grain of the board, calculating its position in the log to very accurately determine the pith location. Together with data collected via high definition 4-sided vision scanning, 4-face grain angle measurements (GrainMap™), and high density laser profile measurements, the pith is modeled down the entire length of the board to very accurately determine knot connectivity within the piece.
The Grade Projector system is unique, and developed by USNR. The Grade Projectors are mounted above the flow and project each board’s grade onto the surface of the board as it passes by the check grader. Tommy said, “It works really well. It helps me because when
I’m on the line I can see what the THG is grading each piece. I really like that feature.”
Rewarded with results
The results the mill is achieving are well received. Tommy commented: “We decreased our trim loss by around 2%, and we’ve cut our manpower by 3 graders. I can’t stress enough the improvement in consistency of the flow at the planer mill. The machine doesn’t get behind in processing. With the
THG running we have increased our throughput capacity by about 4000 ft./ hour.”
Reluctant to share grade uplift percentages, Tommy did express that the mill is achieving good results. He continued, “It’s made a significant difference to our operation; now we can run the planer mill one day less than it takes to produce the lumber in the sawmill. We would definitely do this again”
Tommy noted that, while this was the beta site for proving the THG’s efficacy on SYP, he always felt USNR was fully committed to the project. The relationship remains solid, with Deltic looking at more new USNR equipment to outfit the mill.
Learning the ropes
Training for advanced optimization systems is crucial to achieve the greatest return from the investment. In Deltic’s case, four employees from Waldo attended training at USNR’s Salmon Arm, BC training facility, and this was followed up with extensive training at the mill once the system was operational. In house training can also be performed in cases where mill personnel simply can’t get away for off-site training.
Tommy notes those individuals who were key to the success of this project; Mike Russell, Quality Control, was hands-on from the start and still oversees the THG’s operation, as well Kent Streeter, VP of Wood Products was instrumental to the project, as was Tommy himself.
Now that the grading line project is behind them, Tommy explained that Waldo is continuing to evaluate ways to improve all of its processes. The bottleneck has been pushed further up the line now that the THG has significantly increased the throughput of the planer mill.
■ A check grader on the line views the projected grade decision from the THG and can downgrade the piece if he warrants.
■ A generic screen shows a dry mill grade optimization system processing Southern Yellow Pine. USNR's grade optimization for THG, LHG (transverse and lineal dry mill grading) and BioVision (green mill grading) offers a wide range of flexible features...
■ The Grade Mark Reader reads any marks the check grader has made to downgrade the THG's decision. The revised grade and trim data will be passed to the PLC to adjust the fence paddle's position for that board ahead of trimming.