A high surface hardness from your coating is one of the best ways to increase tool life. Generally speaking, the harder the material or surface, the longer the tool will last. Titanium Carbo-Nitride (TiCN) has a higher surface hardness versus that of Titanium Nitride (TiN). The addition of carbon gives TiCN 33 percent higher hardness and changes the range from about 3,000 to 4,000 Vickers, depending on the manufacturer. With a surface hardness near 9,000 vickers — three times the speed of uncoated tooling. This is the coating of choice for production work in non-ferrous materials because of its higher hardness and its ability to run at two to three times the speed of uncoated tooling.
This is the ability of the coating to protect against abrasion. Although a material may not be hard, elements and processes added during production may aid in the breakdown of cutting edge or forming lobes.
A high coefficient of friction causes increased heat, leading to a shorter coating life or coating failure. However, a lower coefficient of friction can greatly increase tool life. The amount of heat can be reduced by a surface that lacks coarseness or irregularities. This slick surface lets the chips slide off the face of the tool, generating less heat. A higher surface lubricity also can allow for increased speeds when compared to non-coated versions. This further wards off galling of the work material.
This is the point at which the treatment starts to break down. A higher oxidation temperature rating improves success in high heat applications. Although the Titanium Aluminum Nitride (TiAIN) coatings may not be as hard as TiCN at room temperature, it proves to be much more effective in applications where heat is generated. This coating holds its hardness at higher temperatures due to a layer of aluminum oxide that forms between the tool and the cutting chip. This layer transfers heat away from the tool and into the part or chip. Carbide tooling is generally run at higher speeds compared to HSS. This makes TiAIN a preferred choice when coating carbide. Drills and endmills are commonly coated with this type of PVD treatment.