Making new grades

Kiwi Lumber

Making new grades

SAWMILL VISION SCANNING IMPROVES OUTPUT, GRADE ACCURACY

Kiwi Lumber was looking to improve its grade accuracy in the sawmill, to add value to its overall output. With over 110 vision scanning systems installed and operating worldwide, USNR was a natural choice to partner in this endeavor.

The Edger BioVision was installed before the Kiwi team took on the sawmill THG project.

A few years ago Kiwi Lumber knew it needed to update its aging edger optimization system. After careful evaluation it determined that the BioVision Edger solution from USNR would provide the return it was looking to achieve. On the heels of that success, the company came to USNR once again and selected its 4-sided Transverse High Grader to improve grade accuracy at the sawmill trimmer. With the synergy created by the edger and trimmer working in tandem to improve both the accuracy and value of its output, Kiwi is now keen to expand its grades and its product line.

Kiwi Lumber is a privately owned company comprised of three sawmill operations, all on the north island of New Zealand. It was started in 1996 with the purchase of a sawmill at Dannevirke, followed by mills at Putaruru and Masterton. All three mills process Radiata Pine, and Dannevirke and Putaruru cut pruned logs to manufacture appearance grade lumber which is marketed globally. Masterton’s output is structural and marketed primarily within New Zealand.

Duncan Oakley, manager for the Masterton operation, said that the mill produces about 100,000 m3 each year, and added that the mill’s output has grown a lot recently. It runs a single shift – five 12-hour days. Besides the sawmill, it operates a continuous kiln as well as a conventional kiln, a planer mill, and a treatment plant.

Edger BioVision

The Masterton site has seen significant upgrades over the past few years, including vision scanning on its edger line in 2015, and followed this past year with a sawmill Transverse High Grader (THG) on its trimmer line. These projects brought together teams from Kiwi Lumber, USNR and Skookum Technology, USNR’s agent in the region.

Regarding the Edger BioVision upgrade, Duncan said, “The edger was operating with a dated V6 Hemco scanner that had been upgraded with a USNR optimization platform many years ago, and it was becoming a business risk. We knew it needed to be replaced. We thoroughly evaluated whether to go with just profile scanning or full vision scanning. When our evaluation was complete, we determined we would gain additional value with vision scanning. We knew that in some cases we would actually sacrifice conversion, but gain greater value in our output.”

The Edger BioVision project involved installing a new scanner frame outfitted with BioLuma 2900LVG sensors, and the advanced USNR grade optimization system. Duncan related that the mill achieved a good return from the project.

This new scanning technology opens up other opportunities for us to consider in terms of grades or products which we haven't produced before, but may be able to now.

The installation team readies to put the new THG scanner frame in its place.

Sawmill THG

The next phase in improving the mill’s performance was to implement vision scanning at the sawmill trimmer. Duncan commented, “There was a slightly different motivation than we saw with improving the value of our product at the edger. For the trimmer, our target was more to increase our grade accuracy. We had been grading with manual graders, and with the lug speeds we wanted to run we weren’t getting the accuracy that we wanted from manual grading. In going to automated grading at the trimmer line, the goal was to increase our overall accuracy.”

A component of the mill’s decision in choosing a vendor was to select a system that could integrate with the mill’s existing acoustic grader, for evaluating strength of the wood for structural products. Duncan related, “We did weigh other vendors besides USNR. We were happy with the USNR product in terms of what was presented, and we had a good established relationship with USNR with other upgrades we’ve done in recent years.”

The edger's been a good project for us, and its given us a good payback. It's still relatively early days, but we see the THG giving us a good payback too.

According to Duncan, another motivation for choosing the THG was to, “get the left hand talking to the right within the mill.” He said, “With vision scanning on the edger, it might be calling a piece a structural grade. But then when the piece got to the manual grader, he might override that decision. Having the two systems working in different parts of the mill, we can make sure that the decisions are in sync.” He explained further that they were seeing the situation where volume was sacrificed at the edger to gain value, but then they didn’t realize that value when the final grade decision was made on the piece.

The sawmill THG works in tandem with the Edger BioVision system at Kiwi. The THG has significantly improved the accuracy of the grade output.

Duncan reports that now both Edger BioVision and THG systems are operating as anticipated. “Overall the edger’s been a good project for us, and it’s given us a good payback. It’s still relatively early days, but we see the THG giving us a good payback too.” And he related that integration with the acoustic grader is also working as expected. There is a software upgrade that is due to be implemented on the edger, that will incorporate new algorithms for further improved grade accuracy. Duncan said that overall the vision scanning projects were very worthwhile investments.

One key reason for determining the grade in the sawmill is the opportunity to accurately identify the true value of the piece at an earlier stage in the process. If you can sell it green, you may be able to recoup a higher value and not add cost through drying and planing. If you believe it will make the SG8 grade, and go to the expense of drying and planing it, then discover it doesn’t make the grade, you’ve lost time, you’ve lost value and you’ve added cost.

Having the two systems working in different parts of the mill, we can make sure that the decisions are in sync.

Challenges and opportunities

With any new technology but particularly true with automated grading software, development can be an ongoing process. Duncan described one example. “On the edger we had specific challenges around the knots that project through the wane, and with blonde knots. Additional development work was done by USNR to detect those knots.” USNR’s Stephen Wardrop, optimization technician, spent time working at site with the Kiwi team to further tune the systems for improved knot detection.

He continued, “Both systems presented challenges, and I think that’s because of the complexity of tuning the systems to what we wanted to accomplish. Every site is unique, and looking back on the projects now, I think they went as well as they could have.”

Describing the future outlook for the Masterton operation, given the new technologies that have been implemented, Duncan related, “This new scanning technology opens up other opportunities for us to consider in terms of grades or products which we haven’t produced before, but may be able to now. We can also refine our own grading rules to a degree, which we couldn’t do before.”

Ongoing evolution

The vision scanning upgrades in the sawmill puts the Masterton operation in an enviable position to be able to capitalize on its improved output. In 2018 Duncan revealed the mill is upgrading its primary breakdown line with a new log infeed and log handling equipment from USNR.

USNR’s experience in vision scanning includes over 110 installations of systems worldwide. A significant number is in the Australia / New Zealand region, with 20 systems now operating. With this much experience, USNR is a strong partner to consider when planning your next project.