Effect of Hardwood Sawmill Edging and Trimming Practices on Furniture Part Production
In a recent edging and trimming study at three hardwood sawmills, it was observed that the lumber volume produced was approximately 10 percent less than would be necessary to make the most valuable lumber. Furthermore, the excess portion of wood that was removed from the edging and trimming process contained a large percentage of clear wood. In light of rising costs and increasing environmental concerns, the option of producing furniture parts from unedged and untrimmed boards is explored. This research investigates the potential furniture part yields from unedged and untrimmed boards compared to both optimal and actual edging and trimming practices. The resulting volume of cuttings from unedged and untrimmed boards was found to be 25 percent higher than from the actual edged and trimmed lumber produced at the mills.
Influence of edging practices on cutting yields of Alaska birch lumber
Birch lumber is often characterized by a high degree of knots, bark pockets, heartwood, and other features which force sawmill owners to decide whether to edge and trim boards to produce standard grade lumber vs. proprietary grade character-marked lumber. In addition, the edging strategies used with irregularly shaped flitches can greatly influence cut-stock recovery. To investigate this recovery, 143 kiln dried 4/4 birch flitches were obtained from a sawmill in south central Alaska and evaluated by a National Hardwood Lumber Association (NHLA) grader, for board grade and lumber tally. Each flitch was, marked by the lumber grader, indicating where the board would be edged to produce NHLA grade lumber in a production setting. The flitches were transported from Alaska to Oregon State University where they were scanned to produce digital board data. These data were then processed with the computer simulation program CORY (Computerized Optimization of Recoverable Yield) to estimate the cut-stock yield for various levels of edging severity and sound feature (character mark) inclusion. Four edging strategies were evaluated, ranging from unedged (least severe) to wane-free (most severe). As expected, cutting area recoveries and cutting yields were reduced as edging severity was increased. In many cases, however, these differences were minimal. Cutting yields for clear parts were 21.1, 23.7, 26.2, and 27.1 percent for wane-free, actual, light, and unedged strategies respectively. Cutting yields for parts that included sound character features increased by more than double to 44.0, 49.0, 52.7, and 54.0 percent for wane-free, actual, light, and unedged strategies, respectively. These results indicate that finding value-added alternatives for this character-marked birch might prove profitable for some Alaskan sawmills that also produce secondary products such as cabinets and furniture or supply cuttings to these manufacturers.
A Critical Assessment on Functional Attributes and Degradation Mechanism of Membrane Electrode Assembly Components in Direct Methanol Fuel Cells
Direct methanol fuel cells (DMFC) are typically a subset of polymer electrolyte membrane fuel cells (PEMFC) that possess benefits such as fuel flexibility, reduction in plant balance, and benign operation. Due to their benefits, DMFCs could play a substantial role in the future, specifically in replacing Li-ion batteries for portable and military applications. However, the critical concern with DMFCs is the degradation and inadequate reliability that affect the overall value chain and can potentially impede the commercialization of DMFCs. As a consequence, a reliability assessment can provide more insight into a DMFC component’s attributes. The membrane electrode assembly (MEA) is the integral component of the DMFC stack. A comprehensive understanding of its functional attributes and degradation mechanism plays a significant role in its commercialization. The methanol crossover through the membrane, carbon monoxide poisoning, high anode polarization by methanol oxidation, and operating parameters such as temperature, humidity, and others are significant contributions to MEA degradation. In addition, inadequate reliability of the MEA impacts the failure mechanism of DMFC, resulting in poor efficiency. Consequently, this paper provides a comprehensive assessment of several factors leading to the MEA degradation mechanism in order to develop a holistic understanding.