Opportune Grading
Olympic Panel Products (OPP) runs a plywood and overlay business that relies on process control front to back to meet exacting customer requirements and maximize return. New on-line moisture control and camera grading technology are part of that recipe.
By: Rick Massey
In April of 2003, Atlas Holdings LLC of Greenwich, CT, acquired Simpson Timber’s plywood and overlaying operation in Shelton, WA. The result is Olympic Panel Products (OPP) LLC, the single largest plywood overlay facility in the world and the overlaid panel market leader in North America.
According to OPP’s manager of technology and product development, Ken Pratt, little investment had been made at the mill since the installation of a Raute-Mecano VDA G1 camera grader in May 2000.
“At the time of the acquisition, the new owners confirmed their commitment to the mill and wanted to know which areas of production required the most immediate attention. They were told it was dry veneer grading and stacking.”
Purchase of a new Raute 10-bin dry stacking system, complete with a VDA G3 veneer grading and roughness analyzer and integrated DMA dry veneer moisture analyzer followed. The new equipment was installed outside the #2 dryer by October 2004. During this installation, the mill’s existing 10-bin stacker, installed in 1984 at the #4 dryer, got an upgraded VDA/VRA and moisture analyzer, together with new Control Logix controls.
Prior to buying their new dry veneer stacking system from Raute, OPP management benchmarked a number of existing installations.
“Benchmarking gave us the confidence to proceed with the purchase from Raute,” Pratt explains. “We were very impressed in particular with the quality of the stacks we saw at a mill in Canada that produces dried veneer for export. Plus, our prior experience with Raute’s service had been very satisfactory, and we had long relied on their system’s ability to analyze veneer roughness, something their competitors weren’t able to offer,” Pratt adds, noting that the new stacker has a placement accuracy of 3/8".
For OPP, roughness data is very important for several reasons. “By having reliable roughness data, we can determine the performance of the lathe. It also helps to ensure that veneers are correctly dispersed throughout the layup, and that we have the proper face sheets to ensure proper bonding of the overlay material, which includes minimizing telegraphing through the surface.”
Doing the job
To date, mill management says the Raute dry veneer stacking system has met performance expectations. “We have been very satisfied with the performance of the stacking systems, and with the moisture analyzers and camera graders in particular,” Pratt says. “As a result of our own efforts and with the support of Raute, we have calibrated the system to the point where we enjoy 98% on grade performance for moisture, roughness and grade determination.”
Pratt was particularly impressed with the performance of Raute’s DMA moisture analyzer, which he stated has performed at a particularly high level. When laying up plywood, moisture control is particularly important. If the moisture content of the veneer is too high, the glue bond between the plies may be poor, resulting in delamination and press blows. If the moisture level is too low, the surface of the veneer may become case hardened and the glue will not penetrate the veneer to form a proper bond. Panels may also cure too fast after pre-pressing, again resulting in a poor glue bond. Both process control and quality control can be issues.
“Moisture control is very important for us, and analyzing moisture precisely even more so,” Pratt confirms. “From November through the end of January, it can be difficult to have tight control over moisture in the wood. The veneer is cold, more difficult to glue, may be covered with wet tarps and is often purchased from outside sources. Between November 2003 and February 2004, we ran at a level of 1.0% press blows. For the same period during 04/05 following installation of the new VDA/DMA, press blows went down to 0.5% (or by 50%). The mill had expected a drop of about 0.1%, so the DMA far exceeded our expectations in this area.”
The configuration of the new DMA has eliminated gaps between brushes, so the coverage of the veneer sheet is 100%. The mill no longer gets dry veneer mixed in with the wet and they can comfortably grade moisture down to 3-4%.
When asked to comment about the overall performance of the new line, Pratt was complimentary.
“There are many features that make the performance of our new VDA stand out. The illumination system for one has been greatly improved over the original version. It offers very stable intensity over a long period, and we have no complaints from our downstream customers within the mill production environment. Everybody receives the veneer in the condition it should be received. You have to understand that the VDA G3 operates in “black and white” terms, always making the same grading decision with respect to the size of the defects, always doing what it is instructed to. It won’t err on the side of caution and so it will always make the right grading decision, provided it is set up properly. In this case, sufficient attention was paid to setting up the parameters correctly, and so we have been able to enjoy a high level of performance and positive results.”
Pratt also sees benefit in the various grading scenarios offered by the system.
“The so-called ‘What If?’ scenario enables us to optimize our grade mix to satisfy both industry standards and to meet some proprietary requests from customers. For example, if the current specification calls for 1 1/2" knot, and the customer wants a 2" knot, the VDA instantly shows the percentage of veneer that would have yielded the larger knot. It performs its tasks in real time and so does not hamper production. It is also very useful for product development purposes.”
Pratt says that another useful feature is the ‘Critical Defect,’ which identifies where the mill is losing grade.
“If we see a trend in the critical defect, we are able to adjust accordingly. However, it is necessary to work closely with the vendor to determine and control all these different scenarios. If you put in the time up front, you will enjoy the benefits.”
Overall, the installation of the Raute dry veneer grading and stacking system has proven to be a good decision. According to Pratt, overall grade has improved 4-6% for the whole mill since the VDA G3 was installed. Add to that the 50% decrease in press blows made possible through better moisture control and improved roughness detection, and the result has been very satisfactory.
“The Raute dry veneer stacking system with integrated grading, roughness detection and moisture analysis has proven to be a solid investment, one that would be particularly important to mills producing value-added products like Olympic Panel Products.”
Rick Massey is marketing manager with Raute, and when not globetrotting can be found at the supplier’s office in New Westminster, BC.
