New Metal Detector Keeps Mill Running Smoothly: MDI meets challenge Sierra Pacific faced with new bucking system for fencing plant

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A high performance coil was needed to overcome tight space and compact area.


When Sierra Pacific Industries decided to upgrade the log bucking system at its mill in Oroville, California, it was presented with an additional challenge.

“They have a tight environment for a metal detector,” noted Larry Williamson, head technician for Oregon-based Metal Detectors Inc. (MDI). “There’s a lot going on around it. It’s kind of compact.”

With the bucking system upgrade, another machine was located closer to the metal detector, and its working area was more compact. “It made it more environmentally unfriendly to a metal detector in general,” said Larry.

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“Most of the time we like to have a metal detector in a more open space. Theirs was in a very tight space…so they needed a high performance coil to overcome that.”

Sierra Pacific Industries has diverse operations and multiple mills and plants in California and Washington. The Mill at Oroville, located in the foothills about 90 minutes north of Sacramento in the northern portion of the state, manufactures fencing material from cedar logs. The mill and its 128 employees process about 10-13 logs per minute into 6-foot blocks that are manufactured downstream into fencing components, according to plant manager Mike Vinum.

“Everything is very compact and close together,” said Mike. For example, the debarker is only about 7 feet away. MDI was able to supply a metal detector using digital technology that would meet the compact requirements of the application.

“We decided…to go from the older analog technology to the new digital technology, which ended up being much more sensitive,” said Mike.

Mike considered other suppliers but chose to stay with MDI. “I like their equipment, and they offered the digital technology,” he said.

“The installation was challenging for any coil,” said Larry. Sierra Pacific went with MDI’s best coil, the TWA-2000-HD. “That was able to deal with their surroundings and get the sensitivity they wanted.”

“Our capabilities were able to overcome any challenges they had,” said Larry.

The MDI metal detector is critical to the mill’s operations. It detects metal in about 15-20 logs during the course of a shift, noted Mike.

With the changes brought on by the bucking system upgrade, the company’s older MDI system was not able to operate as well, said Larry.

The previous MDI system was 20-25 years old, estimated Larry. “We’ve made a lot of changes in 25 years in coil construction and electronics.” The older model, not as technologically sophisticated, was more prone to false tripping.

The new equipment from Metal Detectors Inc. was installed in March. Mill staff installed the new metal detector in about a day over a weekend. “It’s performing great,” said Mike.

“They did a good job,” said Mike. “It was a successful project.”

Environmental interference, such as variable frequency drives and radio interference, causes challenges for metal detecting systems. Interference may result in false tripping that would force a mill to lower the sensitivity of the metal detector, significantly reducing performance. MDI metal detectors are designed to filter out interference.

The MDI TWA-2000-HD, with MP-4 digital technology, meets expectations in demanding installations and consistently provides top performance. The company’s TWA-2000-HD system can operate at maximum sensitivity even when the largest hardwood logs are being processed.

In addition to preventing sawmill equipment from being damaged by metal fragments and the costly down time that would entail, metal detectors also help ensure employee safety from such incidents, noted Larry. “There’s nothing worse than a saw blade exploding,” he said.

Metal Detectors Inc. has specialized in designing and manufacturing high quality industrial conveyor line metal detectors for the forest products, aggregate, recycling, and other manufacturing industries since 1965. The company has thousands of successful installations worldwide.

“Our track record speaks for itself in the industry,” said Larry. “We have the largest audience out there in terms of customers.”

For more information on Metal Detectors Inc. and its products, visit the company’s website at or call (541) 345-7454.