NA reconfigured front end at the Lakeland mill in BC had a ripple effect, revealing the need for further upgrades downline.w
By Jim Stirling
Sawmill upgrades and improvements are like taxes: The need for them won't go away and they are ignored at your peril. And there's a cause and effect ripple for everything that happens in a mill, from minor tinkering to a major overhaul. Do something in one section of the plant and there are ramifications elsewhere, most with large dollar figures attached. Lakeland Mills Ltd. of Prince George, BC was reminded recently of those eternal truths of the sawmiller's lot and responded with action. A reconfigured front end was revealing problems in the middle of the mill. Bottlenecks occurred too frequently, resulting in downtime and production loss. The equipment was getting tired and parts were hard to hunt down. That was especially true with electronic software, which always seems to come delivered with a best before date of yesterday. Those and associated issues persuaded Lakeland to invest approximately $7 million during the latter half of 1999 to improve the mill's overall productivity and enhance its efficiency in delivering quality lumber to its customers. Lakeland's two-line stud mill places a premium on recovery. Scanning and optimization packages help achieve that by maintaining high piece counts through the machine centres and utilizing fine kerf sawing. About five years ago, Lakeland embarked on a project to rebuild the end dogging head rig on the mill's large log side.
The line breaks down 22-centimeter top diameters into 2.4 metre bolts. The revitalized head rig was equipped with a new scanning/optimization package to help position every log in the end dogger to extract the best recovery. Lakeland recognized at that time improvements would be required downstream, including upgrading the abilities of the mill's edging equipment. Upgrading machine centres, alleviating the bottlenecks and reducing downtime is expected to deliver a production increase, says Lakeland president Keith Anderson. The goal was to boost the average production per shift from 255,000 board feet to 270,000 board feet, he adds. The latest cycle of improvements began with the installation of a new CAE McGehee vertical double arbor gang edger. "Our previous machine could cut only four inch cants, this one can saw six inch," says Ernie Sarrazin, Lakeland's purchasing/ project manager. The new edger sidesteps an old problem of cant ends hanging on saws and inflicting damage to them. It also contributes more accuracy and a production increase through less downtime, says Sarrazin. A new concrete support was installed to stabilize and maximize the performance of the 19,522kilogram unit. A single horizontal band mill was replaced by a twin horizontal band saw supplied by Flare International Sawmill Systems Ltd. The addition has removed one of the middlemill's more irksome bottlenecks. What was happening before the twin band was every piece that would give more than a two inch side flitch had to travel on a merry-go-round system for reprocessing. "We found lots of cants were coming back for second and third cuts," says Sarrazin. The twin band saves considerable time and also fits in the limited physical space available.
The engineers at Flare felt they could reduce the size of the machine to install it in the space allowed, explains Sarrazin. They provided adequate room for the equipment's press rolls partly by expanding the machine's base without enlarging the machine itself. The Lakeland team continued its assessment of downstream product flow. They didn't have a good means of breakdown of side flitches from the horizontal band mill and head rig to feed the board edgers, says Sarrazin. "We were losing lug spaces through the optimizer." More storage space for the lug loader system was created by an addition to the mill's south side. The extra space was augmented with the installation of an unscrambler and board turner. The company has also installed an automatic lug loading system. "We're still working on it. We want at least a 90 per cent lug fill rate." Part of the lug loader design includes a top press system to keep pieces from shingling. One of the problems is the diverse size of material the system has to move at speeds up to 55 lugs/minute through the scanners. The pieces have differing widths and widths can further vary within the length of each board.
Anew CAE Newnes optimizer with more laser scanning lines was added
and it produces a much more accurate profile reading of each piece than the system
it replaced. It was becoming increasingly difficult to find parts for what had too rapidly
become an obsolete system. Prior to the latest changes, the mill's edging system
incorporated a horizontal single board machine and a multiboard edger. The mill now
features two identical McGehee horizontal board edgers supplied by CAE Newnes. They have
Newnes positioners and chargers on them and CAE Newnes was also responsible for the
programming from the unscrambler to the optimized edging. Each edger is capable of running
60 per cent of the mill's flow should it be required to do so. The updated configuration
utilizes the out feed from the old multiboard edger to the mill's sort out table.
The second new edger out feed differs in that it can feed the 2x4 transfer or the sort out table. Before, if the sorter went down, the edgers couldn't operate. That is no longer the case. A deep pile option on the sorter infeed transfer again provides the ability to operate with the sorter down, adds Sarrazin. At the front end, Lakeland is also working on a new scanning system on the head rig to further improve lumber recovery and productivity. Its partner in the venture is Comact Inc which relished the opportunity to provide Lakeland with a custom solution. "We wanted a really accurate scan of the whole log," says Sarrazin. "We couldn't look at the whole log with two scanner heads working on an X and Y axis." What has emerged from the collaboration is what Comact calls SnapScan, an end dogging snapshot scanning system. Lakeland's system utilizes three scanning heads.
The multilaser, multi camera system combines speed and precision to produce full profile measurements and optimization, says Comact. "With three scanning heads we can see almost the entire circle of the log," says Sarrazin. The system is run by a bank of Pentium computers. A new dust control system from Allied Blower & Sheet Metal Ltd in Surrey, BC is also part of the latest spate of improvements. The system removes dust and fine wood particulates from around the mill's main machine centres, creating a better quality environment for production and maintenance staff. It also enhances the performance and visibility of high-tech scanning equipment and "eyes" regulating product flow.
The extracted material is blown through a piping system to the mill's hog fuel bin. Most of it goes to Lakeland's pulp mill customer and into the in-house energy system. Bark is the main wood waste for energy production but wood fines are mixed to maintain temperatures. Lakeland assembled a good team of consultants and contractors to minimize the disruptions surrounding the major equipment installations and steering through the startup curve. The group included Ted Foster of Resource Savers Industries in Bellingham, Washington who has been providing technical know-how and system design drawings since Lakeland took a vanguard position in the end dogging technique of primary breakdown.
The principal engineering consultant was Stolberg Engineering Ltd of Richmond, BC with Rod Gronlund. Mechanical installations were handled by J D T Construction Ltd and Electrical Services & Contracting Ltd was the electrical contractor. Both companies are Prince George based as is C I F Construction Ltd, the concrete supplier. Now, with the middle part of the mill performing to expectations, the question arises: Can work to the back end be far behind?
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