The tests within the scope of this project assessed the efficiency of manually operated carriage, edging and trimming work stations. Simulations also demonstrated how optimization equipment used to evaluate the shape of logs or lumber affected the efficiency of these work centres.
Our evaluation of manually operated workstations revealed a high error rate at the log carriage as well as at edging and trimming stations. Operator performance varies greatly and operators generally tend to focus on volume, at the expense of value. For a sawmill with an annual production of 10 MMfbm, a complete elimination of these errors could generate additional income in the range of $200,000 for the log carriage, and $500,000 to $700,000 for the edging and trimming stations.
Most of the losses occurring at the carriage could be avoided by installing a 3-D optimization system, which would result in a payback period of less than two years. Moreover, these calculations do not include any increases in productivity that such a system would also provide.
However, this is not the case for optimization of the trimming and edging stations. Given that current technology cannot yet identify appearance defects, only some of the current losses could be avoided if these stations were optimized. Our results show that edging and trimming stations optimized solely for wane could yield returns on investment in the order of 25.3% and 2.3%, respectively. For a 10 MMfbm sawmill, these percentages correspond to $126,000 in additional income for the edging station, but only $15,400 in additional income for the trimming station.
The operator’s ability to step in and change the optimizer solution was not taken into consideration in evaluating the samples. Therefore, the additional income generated by optimizing the edging and trimming stations must lie somewhere between the income generated by optimizing solely for wane and that generated by optimizing for all defects. However, there is less interest in optimizing secondary breakdown stations because of high equipment purchase and installation costs (up to $800,000). In this context, only edging stations requiring increased productivity would benefit from this technology, which can operate at speeds greater than 25 boards per minute.