In a major move to streamline its operations, Tolko Industries Ltd closed the plywood section of its Kelowna, British Columbia, mill last January and, at the same time, modernised and speeded the mill’s veneer section. Less availability of high-quality peeler logs worked into the decision to overhaul this mill, built in 1957.
But the project was also tied in with the company’s other mills. "The way the sheathing market has been going we are basically competing with each other," said Brett Patricny, plant quality control supervisor.
"We are going to peel veneer, recover high-value products, and then use the sheathing material to produce sheathing in the other mills," he said.
The spectre of beetle-killed trees hangs over most of this part of the world. Mr Patricny said the beetle kill is coming into this area "really, really quick. We can work with beetle kill standing in the bush for up to two years. We are not peeling much. It is used for core. Our stud mill saws it. About half of it is lodgepole pine".
The veneer line peels 80% spruce-pine-fir and 20% Douglas fir, operating with a crew of 40, with one 10-hour shift on the lathe and two 101’2 hour drying shifts.
The Premier lathe with Coe drive has drawn most of the recent work, with an Altec x-y scanner 3-D from LMI Technologies accommodating up to 64 lasers, and new lathe controls. Tolko and Premier collaborated on a proprietary, custom-made carriage design which has emphasis on electric motors rather than hydraulics for moving the carriage. There are now two AC motors on the lathe.
For super-fine control, up to 200,000 readings are taken on each block with the computerised scanner optimiser, providing very even thickness – normally ±0.008in. This system provides thicknesses in the ±0.002in range.
The roller bar was reduced from 33’4in to 21’2in and that provides a smaller peel, according to Mr Patricny.
The average block diameter is 101’2in, with 3 to 4,000 blocks peeled per shift. Maximum diameter is 35in with a 71’2in minimum. The mill peels down to a 3in core diameter. The veneer off-bears to three trays operating at speeds up to 1,000fpm. Past the clipper, it proceeds through a Forintek-Westmill LightSORT moisture detector based on a fairly simple principle that the higher the moisture content, the more light passes through the sheet. But augmenting that principle requires quite sophisticated equipment.
It uses CCD camera and LED light transmission, pulsing specific wavelength light through the veneer where the camera takes an image. Algorithms determine the exact peak and average moisture content for each sheet. It works well with high moisture content veneer, which is a problem for radio frequency (RF) sensor heads.
Forintek ran tests on the Tolko system and found a 10% production gain, based on 7.6% on dryer output, 2.5% gain in target dry veneer, and a 2.7% reduction in re-dry.
Brian Martin, Westmill Machine Automation general manager, said the system does not require veneer contact and, unlike RF measuring, veneer variables are not a problem. The system also checks the entire sheet, rather than just the veneer passing under the heads as in other systems. This not only results in a highly accurate sort and consequent increase in dryer productivity, but also increases final veneer quality, he said.
The veneer off-bears to six bins – two for heartwood, two for medium, two for heavy.
A Raute direct-fired jet gas dryer has four decks, while two six-deck steam dryers have been in place since the plant was built in 1957. A Coe scanner is on dryer number one and a Metriguard is installed.
Tolko built its own stackers, with 18 bins on one and 12 on the other. Samuels automated strapping will soon be added.
Most of the veneer is used within Tolko’s other plants, with the aim of developing a group of specific customers and serving them well.
Tolko separates species in the bush and is not buying so many logs. The plant operates one 10-hour lathe shift and two 101’2 hour drying shifts with production of 1.7m ft2 (3’8in basis) weekly. The mill has a crew of 40.
Log storage is all in water, with the log dump on the far side of the 13’4-mile-wide lake. Logs are graded on the far side and rafted across the lake; though winters are quite cold, it rarely freezes. In winter, frozen logs from the bush are common and they get a thawing head start in the lake.
Logs come to a common cut-up for veneer and the adjoining stud mill. They go through a ring debarker, with hogged bark sent to the power plant, which provides six to seven megawatts of power to make the mill almost self-sufficient.
Three hot water vats heat veneer blocks to 100ºF (37.8ºC) core temperature.
Both truck and rail shipping move product out. A rail siding holds two cars behind the mill, with room for another four.