| Abstract: | Quality attributes of the finished product are the primary focus of the fiberboard manufacturing process. The finished product should withstand stresses involved in its use in construction, and stresses acting on it over time after its application. Fiberboard manufacturers use modulus of rupture (MOR), calculated from directional breaking load and pressed thickness samples of the finished product, as one indication of product strength. For this reason, MOR is closely monitored as a part of the production process. The goal of the present study was to relate breaking load and pressed thickness to upstream factors of production, allowing mill personnel to increase MOR by making changes to these factors. However, a change in a factor might not influence only the MOR but also downstream factors related to MOR. Therefore, two types of relationships were evaluated: 1) the relationships between factors and 2) the relationships between those factors and MOR. Two data sets representing 20 selected factors were collected. Regression analysis was used to document the strength of tested relationships. Once the relationships were analyzed, a series of consistency checks were performed to determine whether the slopes and intercepts of the respective relationships from each data set were equal. Several relationships from the first and second data sets were found to have equal intercepts and slopes. Some upstream factors either influenced MOR directly or influenced downstream factors that were related to MOR. Conversely, many relationships among factors were found in which the downstream factor did not influence MOR. Variations in line speed, drain time or wet weight influenced dryer temperatures; however, within the range of the data dryer temperatures did not influence either breaking load or pressed thickness. Variations in average fiber size, measured as drain time, influenced MOR and wet caliper. Increasing dry weight increased both the machine and cross direction breaking loads without influencing pressed thickness. Increasing press time increased cross direction breaking loads, indicating that average MOR could be increased regardless of the influences of upstream factors on the mat. Quantifying the influences of upstream factors on downstream factors allows mill personnel to make informed decisions when confronted with poor quality fiberboard. With prior knowledge of which factors can be adjusted to increase MOR, mill personnel can then concentrate on producing quality siding at the lowest cost to the producer. |
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