The forestry sector, being a major economic pillar in Canada, encompasses wood processing operations requiring tools that are both efficient and resistant to wear. Among these tools, the squaring knife plays a crucial role. This thesis is dedicated to the characterization of wear on squaring knives and delves deeply into the performance of tool steels during the initial wood processing. The study initially addresses wear mechanisms, exploring the causes and manifestations of wear, as well as their impact on the performance of squaring knives. Three tool steels were examined. It emerges from this study that these various steels are subjected to a combination of wear mechanisms, notably wear by abrasion, adhesion wear, and impact wear. However, the predominant mechanisms turn out to be abrasion, visible through scratches and the blunting of the cutting edge, and impact wear, manifested through flaking and material tear-outs.
Furthermore, a wear quantification methodology was developed, based on a three-dimensional approach, allowing for the estimation of lost material volume as well as the volume lost specifically by abrasive wear, highlighting the complexity of machining in the wood industry. The results underscore the significance of coatings to enhance the wear resistance of knives. However, the presence of material tear-outs on some coated knives suggests potential fragility under challenging machining conditions.
Additionally, an abrasion wear testing machine with a rubber wheel present at DK-Spec, our industrial partner, has been refurbished, thus enabling wear tests according to the ASTM G65 standard. Moreover, an analysis in accordance with the ASTM G65 standard was conducted to evaluate the abrasive wear resistance of the steels. The results indicate that the coated steel A8mod+1%W offers the best resistance among the coated steels, with a wear reduction of 49%. In contrast, although steel W360 demonstrated excellent intrinsic resistance, the coating did not yield a significant improvement for this steel.
This thesis, through its meticulous exploration and findings, aims to contribute to a better understanding of the wear phenomena of squaring knives, and to propose optimized directions for the selection of tool steels in the wood processing industry.
| Date | 11 Dec 2023 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Mohammad Jahazi (Supervisor) |
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Mbakop Nanshie, V. (Author),
Jahazi (Supervisor),
11 Dec 2023Student thesis: Master's thesis › Master in Engineering: Mechanical Engineering