A new device is designed to find defects that a surface scanner can't see. The ultrasonic detection device can be used for voids and internal cracks, and is being tested for the first time in a production environment. Baird Bros. Sawmill Inc. specializes in mouldings, handrails, stair parts, flooring and interior doors. The Canfield, Ohio, company installed a WoodEye scanner in March 2005, explains Terry Baird.
In the rough mill
The WoodEye surface scanner has been in the rough mill since that time, looking for knots, surface cuts, wane holes and dimensional errors. Baird says the scanner is all visual, and a lot of what the scanner sees depends on how well the lumber is surfaced. For the past few months, Baird has been testing a separate ultrasonic device, also from WoodEye, that looks for voids in the wood and breaks in the actual fiber.
"With the scanner being all visual, if it looks like a defect, then it is a defect," Baird says. "If you drew a line on the board, it would look like a crack to the scanner."
Baird points out that the ultrasonic device, a joint effort of several companies, including WoodEye and Baird, is a work in progress that hasn't yet been proven in a high-volume production environment,
How it works
The ultrasonic developers have tested the device in limited production by running a board through by hand. "We've given them a production line to test their product on," Baird says. The ultrasonic device itself is comprised of two rollers filled with oil. A signal is transmitted from one roll to the other as the rollers touch the wood, which is fed through the two rollers. Any defect will show up on a graph that an operator can see.
"The ultrasonic will tell the WoodEye that it has seen a defect at a certain location on the board, and the WoodEye applies that to what it has seen, and then makes the cutting solution," Baird says. "They'll work together."
If the WoodEye or the ultrasonic determine a bad area, it is cut out by the Paul saw, which is right after the WoodEye in the rough mill line. "The WoodEye is the brains of the operation, telling the Paul saw where to cut."
One problem in the testing phase is that the wood must go through the rolls just right, with a consistent pressure from end to end.
"The ultrasonic rolls have to be on the wood from the leading edge to the tail end of the board, at a consistent pressure, the whole way through," Baird says. "They can't be bouncing on the wood.
"The big benefit would be more accurate defect recognition," he says.
"It shouldn't cut out things that it thinks are defects but aren't. It also should be more accurate on recognizing defects that it can't see that are there."
An example of this is internal honeycomb that doesn't show up on the surface. "That's always been a tough one with red oak. If it closes on the surface, you don't know until you crosscut the board."
So far, Baird is having better results with poplar than red oak. The device is not expected to be used on cherry.
The rough mill at Baird Bros. starts out with a Yates-American 326 planer. Next is a Mid-Oregon gang rip saw, with a clear board scanner that isn't looking for defects, but is checking the width of the board and creating a rip solution based on width. A Weima grinder is used for waste pieces.
Automated Lumber Handling made a curved conveyor to sort strips singly so they can go into the scanner automatically. Next is the ultrasonic device, immediately followed by the WoodEye scanner. Then a new Paul C14 optimizing chop saw cuts pieces based on the WoodEye scanner. Pieces are sorted, and run through an inkjet printer behind the Paul saw. There is also a second Weima grinder.
A Conception CRP 2000 fingerjointer was installed two years ago, and runs two days a week, used mostly for fingerjointed poplar mouldings and to reclaim short pieces. Baird has dry kilns, and lumber comes from Ohio, Pennsylvania and West Virginia. The company makes its own electricity with natural gas engines.
Baird's primary products are mouldings and S4S and flooring, followed by doors, primarily interior doors. A lot of business is retail, including homeowner remodeling. A retail store sells wood components along with saw blades and other items. Customers can go into inventory and pick out the pieces they want, so high-quality defect recognition is very important to Baird.
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