The Ultimate Guide to Lumber Moisture Control – Part 3: Planer

Part 3 of a 4-part series – As seen in the December issue of Timber Processing.

Once kiln-dried lumber reaches the planer, mills have one final opportunity to optimize board moisture before their product is sent to customers. Today, using advanced moisture-sensing technologies, mills can utilize their planer to improve overall productivity, enhance grade recovery and reduce, or even eliminate, wet claims.

It is these kinds of advanced moisture sensors that Canfor Southern Pine Quality Control Tech, Shaw Bennett, uses to better manage planer output. And, his results go beyond improved grade recovery. “Before [upgrading to a planer moisture] system, we used to have packs on hold from our inspection agency due to wet lumber, but this has not been an issue since installation,” Bennett said. “It has helped us prevent Low E Values caused by too much moisture in boards.”

Thanks to real-time data, mills that install these moisture sensor advancements can accurately track and sort their best lumber grades. With the right advanced sensor set-up, calibration and connected Industrial Internet of Things (IIoT) oversight, the planer can be set to deliver solutions, like moisture-driven cut-in-two options and trim opportunities, providing results and savings that improve the mill’s bottom line.

Moisture and the Planer

Eventually, all the work of the sawmill and kiln is technically evaluated at the planer. Now automatic grading systems can apply moisture as a parameter of classification using data, provided by non-contact moisture sensors. This allows the results of drying to be more easily quantified, and for lumber to be more effectively classified into grades. Before automatic grading integration, it was not so easy. Lumber went through a moisture meter and, if the wood was wet, it was sprayed with a paint marker that a manual grader would eventually see. The manual grader would then classify the board as Economy, instead of Prime or #2 & Better.

The next generation of transverse moisture meters began to improve data readings and provide more robust moisture information; Mills immediately realized an increase in grade recovery. These moisture sensors use capacitive technologies to take multiple readings per board and then deliver automatic data hand-offs for grade optimization by machine.

With data provided by these transverse sensors, mills can also consider choosing to drop out wet boards before they are dressed, allowing them to be re-dried at nominal size. Strategic drop-outs avoid grade reduction and wet claims.

Today, the latest generation of High Definition (HD) moisture-sensing systems are providing even richer moisture mapping capabilities. Using smaller sensors, placed more frequently, and positioned on both sides of the board, HD technology is emerging as a solution for surface and/or core wet determination.
HD technology compliments resolution for the latest versions of laser and scanning sensors associated with automatic grading decisions. This provides easy optimizations for product sales into engineered wood product markets such as Finger Joint and Cross Laminated Timber.

Managing Cost

Ultimately, these advanced planer moisture systems have been developed to help mills manage difficult cost and productivity issues. For instance, moisture sensors can alert planer operators when too many wet boards arrive at the planer. This gives the mill a chance to make a value decision using real-time data, and an opportunity to possibly back the boards out for re-drying, or to move forward and accept the economics of lower-grade values.

When lumber arrives too dry, the mill has an opportunity to mitigate the impact. Over-dried lumber can affect productivity, and increase hard costs, as twists and warps hold potential to jam machinery and even damage blades. The down-time to stop a run and perform maintenance is lost money for the mill.

Also, if dry boards have become wet again, operators need to know if it is surface or core moisture. By the time lumber goes moldy or stains, it is too late and the value is lost.

Correlating Data

With all of the advanced moisture sensor systems available, the most accurate and successful mills will be using real-time data to drive better lumber production. This data sets up on a correlation created across three determined data points, the handheld meter of the grading agency, the handheld meter of the mill, and the automated moisture sensing systems installed at the mill. It is a correlation that allows mills to reliably reach desired moisture content expectations for their end products.

“For us, having the MC Pro 2400 HDNC system has helped limit the amount of over-dried lumber and wet lumber,” Bennett said. “This has not only helped our production, but also our grade out.”

Future of Planer Moisture

Thanks to ongoing advancements in moisture sensors, lumber mills are realizing savings in grade recovery at the planer. They are also seeing marked improvements in productivity. Not that long ago, an operator would have to stop the line and change system sensitivity when the board size changed. Today, that old technology has been replaced by improved sensor sensitivity and software integration that takes care of productivity changes automatically.

Moving forward, lumber mills will want to benefit from the advantages of these advanced moisture systems in the planer – the latest HD systems are leading the way. Perhaps the biggest benefit is realized when mills capture, analyze and respond to their real-time moisture readings across all areas of the lumber mill. That is when process integration and active IIoT connections can provide their most impactful improvements using real time, data-driven moisture sensor systems.

<<Read Part 2: Kiln Drying

Read Part 4: Sawmill>>