## 3 Results and Discussion
### Results of Industrial Tests
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Saw Identification**} & \multicolumn{2}{c}{**After 480 min of Utilization (between 0 min**} & \multicolumn{2}{c}{**After 480 min of Utilization (between 480 min**} \\  & \multicolumn{2}{c}{**and 480 min of Sawing)**} & \multicolumn{2}{c}{**and 960 min of Sawing)**} \\ \cline{2-7}  & **Clearance Face** & **Rake Face** & **Wear Land** & **Clearance Face** & **Rake Face** & **Wear Land** \\ \hline Decrease in wear rate of saw & \multirow{2}{*}{38\%} & \multirow{2}{*}{51\%} & \multirow{2}{*}{46\%} & \multirow{2}{*}{77\%} & \multirow{2}{*}{41\%} & \multirow{2}{*}{73\%} \\ \#2 compared to saw \#4 & & & & & & \\ \hline Decrease in wear rate of saw & \multirow{2}{*}{21\%} & \multirow{2}{*}{11\%} & \multirow{2}{*}{16\%} & \multirow{2}{*}{26\%} & \multirow{2}{*}{53\%} & \multirow{2}{*}{41\%} \\ \#2 compared to saw \#6 & & & & & & \\ \hline \hline \end{tabular} Saw #2: Coated and edge-modified saw. Saw #4: Coated and up-sharp saw. Saw #6: Uncoated and edge-modified saw.  
\end{table} 
Table 9: Decrease in wear rate (percentage) when using coated and edge-modified saw. SEM characterization of the tip corners of the saws tested after 480 and 960 min of sawing are presented in Figure 23. The micrographs were taken from the rake face view of the tips. The coating did not provide advantages for cutting edge protection of saw #4 as it was peeled off from the sharp edges and corners of the tips (Figure 23b,e). The corner of the up-sharp tip (Figure 23e) sustained significant local breakage, highlighting the weakness of the tip in this area. However, no apparent chipping or breakage could be seen for saws #2 and 6 (Figure 23a,c,d,f). The reason is attributed to the increased corner strength brought about by the honing process. Furthermore, after 480 min of sawing, the rake face of some tips of saw #4 experienced cratering, mainly located at the corners (Figure 23b). The latter observation is attributed to the synergetic interaction of the abrasive action of chips over the rake face and the frictional heat generated at the wood-tip interface as the primary cutting edge was chipped. Figure 23: SEM micrographs of the corners of the tips (rake face view): (**a–c**) saws #2, 4, and 6, respectively after 480 min of sawing and (**d–f**) saws #2, 4, and 6, respectively after 960 min of sawing. Figure 22: SEM micrographs of the rake face of (**a–c**) saws #2, 4, and 6, respectively after 480 min of sawing, and (**d–f**) saws #2, 4, and 6, respectively after 960 min of sawing. Representative SEM micrographs of the cutting edge after 480 min of sawing are presented in Figure 24. The main wear mechanism involved for saw #4 was chipping (Figure 24b,e). It is well established that the stress concentration on the cutting edge of the tips with an up-sharp geometry is high [52], which leads to chipping and early breakdown of the cutting edge [53]. On the contrary, most tips of saws that have undergone edge modification (saws #2 and #6) appeared to be intact with only a few tips experiencing microchipping (Figure 24a,d,c,f). According to [PERSON] et al. [7], edge preparation improved the performance of cutting tools during metal machining by reducing the rate of chipping. It is reported that cutting edge preparation has the potential to alleviate the issues of edge chipping by eliminating typical edge defects such as micro fractures and irregularities [53]. In addition, a crack perpendicular to the cutting edge of saw #4 was observed, which is due to fatigue in combination with frictional heat. It is well known that heat is generated during wood cutting. Wood exhibits a low thermal conductivity, and therefore heat is either accumulated on the cutting edge and, to a much lesser extent, released into the surrounding air [9] Thus, the cutting edge experiences periodic temperature fluctuations. This situation combined with the cyclic nature of the cutting force during sawing led to crack initiation and propagation, [54] as shown in Figure 24e.