Sawmill Moisture Sensors

Lumber mills have innovated over the years to adapt to the demands of the communities they serve. As those communities became more focused on employee safety and environmental controls, mills examined all aspects of lumber recovery to reduce waste and increase profitability. Finna Sensors has been instrumental in providing solutions to address these concerns – especially as it relates to green sorting and tracking of lumber once it has been cut from logs in the sawmill.

After primary breakdown one of the most strategic downstream processes is to sort lumber into ‘similar’ groups before kiln drying. Kiln drying lumber serves two main purposes: removing water to make all the boards more uniform and to increase the structural stability and strength of each board. Sorting by dimension is the logical starting block, but due to the natural variability of wood, two boards of the same size can have very different properties. The highest returns are realized when another level of sorting is implemented; Weight and/or Moisture sorting. Weight sorting is effective when only a single species is being processed at a time. Moisture sorting is effective with multiple species production or species with high variability. By including weight, moisture and geometric volume into expanded sorts, it allows for more targeted kiln schedules to ensure a more uniform product and increased throughput. For example, if a 2” x 8” piece is found to be very heavy or wet, it would be put into a “heavy/wet” sort for that dimension. Conversely, a light or dry piece would be placed into the other corresponding sort.

Key Moisture Sorting Technology

Finna Sensors has offered solutions for the sawmill for the last 20 years. Through its acquisition of Northern Milltech (NMI) in 2008, it gained key moisture sorting technology used by lumber mills throughout North America. Since then, it has expanded its offering to include sorting by both moisture and weight, as well as, software solutions to track pieces from the sawmill through the kilns to the planer. This allows operators to understand how sort decisions affect final yield.

• The moisture sort system has become significantly more advanced over the years to now include scanning of both faces of a board, multiple sensor sizes to fit more sensors between chain runs and Internet of Things (IOT) functions to increase performance.
• Weight is also an option now for sorting. It can be used on its own, or used with moisture measurement to create a total solution for frozen and non-frozen lumber.
• Tracking software has improved to include tagging each piece to determine how sort decisions affect profit.

Rapid advancement in sensor technology for the sawmill operations has resulted in tremendous return on investment. Sorting by moisture content can improve dry kiln productivity from 10% to 15%, providing a typical payback of less than 8 months.