OSB Process Moisture Control

Strand Moisture Content (M.C.) is one of the most critical process variables in Oriented Strand Board (OSB) manufacturing. Dryer optimization and moisture control are very important factors affecting production levels and consistent panel quality. Both are critical to having a panel board process reach its full potential. A proper balance between drying process feed rate, temperature, air flow and wet strand M.C. needs to be maintained for consistent outlet strand moisture contents. Dryer temperature PID control loops need to be properly tuned to handle process changes. Long lag times are typical for OSB Dryers, which makes proper tuning difficult and time-consuming, but not impossible.

PID tuning, control system or field equipment problems can result in cycling of the Dryer temperature which negatively impacts strand moisture content. At the top of the temperature swing, over-drying of the strands occurs and the risk of dryer fires increases. At the bottom end, stand M.C. is too high for the OSB process and can cause offgrade due to steam pressure build-up in the panels during hot-pressing (blows). Usually, some adjustments can be made to the pressing parameters to compensate, but these are generally accompanied by reduced production levels.

In addition to the strand M.C. swings and their negative impact on the OSB process, there are other important considerations regarding temperature cycling. Mechanical stresses on Dryer components, increased energy consumption and emissions, as well as the increased risk of drying process fires are all important factors to consider.

We understand the variables affecting Dryer control and can identify problems with PID control loops, field devices and dryer equipment. We can help keep moisture content variability to a minimum. Over the years, we have worked with many different types of moisture meters, such as Infrared and capacitance-based, in a variety of process locations. Reliable on-line M.C. measurements are important to the Operators and computer controls.

We can help troubleshoot and optimize your OSB drying process, reduce moisture variation, improve panel quality and lower your manufacturing costs.