###### Abstract
It refers to the design of a controlled geometry of the cutting edge to reduce the impact of initial edge defects and micro-chipping that are inherent in all cutting tools [6]. Engineered modification of cutting edges has become more frequent in the metal cutting industry but received close to no attention in the wood processing sector. Proper edge preparation has the potential to improve the performance of cutting tools by delaying the onset of chipping and abrasive wear [7]. The microgeometry of the cutting edge is defined by the form factor K (K = S\(\gamma\)/S\(\alpha\)), as presented in Figure 1[8]. The K = 1 defines the radius-honed profile, while K > 1 and K < 1 describe the waterfall and reverse waterfall home profiles, respectively [8]. Surface treatment is another solution to improve tool life. Hard and adherent coatings obtained by physical vapor deposition (PVD) have been recently used in wood machining. However, up to now, they have seen limited application for circular saws in primary wood processing. Coatings for wood cutting tools are typically characterized as having a high level of hardness and most importantly, a low coefficient of friction that lead to reduced wear rate [9]. In addition, due to the visco-elastic properties of wood and its high coefficient of friction, good adhesion to the substrate is another crucial feature of an adequate coating [10]. TiN and CrN are the most popular coatings for wood cutting tools. However, Cr-based coatings have attracted more attention in recent decades [11; 12]. By adding a third element such as Vanadium (V), Aluminum (Al), Molybdenum (Mo), Silicon (Si), etc. in the system, nitride coatings show a good potential for increasing hardness and wear resistance of carbide-tipped circular saws. For instance, additions of Si increase the coating's  
Figure 1: Parameters used in edge geometry determination [8]. mechanical properties and abrasive wear resistance. Incorporating Al into a nitride-based coating results in the formation of a structure with high oxidation resistance and thermal stability [13]. Moreover, the development of multilayer coatings is advantageous to enhance the comprehensive properties of the overall coating by forming a layered microstructure that hinders crack propagation [14]. [PERSON] et al. [15] conducted an industrial cutting test with a CrN/CrWN multilayer coating deposited on a WC-Co cutting tool. The test resulted in an important increase of the total length of machined wood compared to the case where the coating was applied as a single-layer. The latter result was attributed to the interfacial bonding between layers restraining microcrack propagation in the coating, thus preventing premature failure of the cutting edge. Adding carbon to chromium nitride (CrN) coatings was also shown to improve mechanical properties, fatigue strength and tribological properties [16]. As reported by [PERSON] and [PERSON] [10], CrCN/CrN coatings had a wear rate ten times lower than that observed for a TiAlN/TiN coating. The reason was explained by the higher value of ion potential of CrO\({}_{2}\) (7.3) compared to TiO\({}_{2}\) (5.4). Indeed, when the ionic potential is higher, the cation in that oxide is more masked by the surrounding anions and the oxide easily shears accordingly [17]. Carbon-based coatings like diamond-like carbon (DLC) are characterized with having a lower coefficient of friction, high hardness, and high wear resistance. It is made of amorphous carbon, which is a disordered network of carbon atoms connected by a mixture of sp\({}^{3}\) and sp\({}^{2}\) coordinated bonds [18]. The formation of an easy-shear-ribofilm on the surface of the counter body contributes to a lower friction coefficient [19]. [PERSON] and [PERSON] [20] showed that the tools coated with DLC and multilayer CrN coatings performed much better compared to that of the uncoated tools when machining spruce wood.