In the lumber industry today, process monitoring systems are still relatively uncommon, in comparison to other industrial sectors, where these systems are widespread and essential to profitability. We came up with the idea of adapting the Optitek sawmill simulator to serve as a monitoring and process control tool. The idea is to use the scanners at the entrance of processing lines to gather log profile data in order to create a simulated sawmill production data set, which can then be compared in real time to actual performance.
One company, AbitibiBowater, was interested in this proposal and designated one of its sawmills as the site for a pilot project. The development and implementation of the Optitek monitoring system took two years. The first year focused primarily on project planning, adapting the Optitek simulator to operate in real time, and creating a web portal named Optitek Evolution. During the second year, the system was installed in the mill and began operating. In parallel, Optitek was used to create a complete model of the sawmill and the results were then confirmed through a series of tests conducted at the mill.
The purpose of validation was to model mill performance as accurately as possible in order to efficiently monitor it. Tests at the mill allowed us to check the precision of log scanners, quantify log breakdown errors, and evaluate the actual performance of the sawmill. Key indicators, such as the consumption factor (m³/Mbf), economic performance ($/m³), as well as lumber distribution, were used to validate the model. Filtering was required to minimize the impact of log movement as logs passed through the scanners.
After validating the system, mill personnel were trained in this new technology and monitoring began. An initial reference period allowed us to test the system to determine the correct monitoring frequency. However, we did observe some restrictions, given the mill’s operating procedures. Significant quantities of wood regularly enter or exit the mill, which significantly influences the performance indicators for a given shift. Consequently, it becomes impossible to generate reliable indicators over shorter time intervals (2 hours for example). For monitoring to be valid, as a minimum, it must be calculated on the basis of a moving average over eight hours, based on data collected every two hours.
Other factors that affect the minimum monitoring period are batch-type operations and the accumulation capacity before trimming. Under ideal conditions, a sawmill operating without any transfer of wood outdoors, and on a "scan and set" mode, would be able to conduct accurate monitoring over a two-hour period or less.