Niagara Cutter N53976 Carbide Ball Nose End Mill, Inch, TiAlN Finish, Roughing and Finishing Cut, 30 Degree Helix, 4 Flutes, 4" Overall Length, 0.250" Cutting Diameter, 0.250" Shank Diameter Four flutes produce a better finish than fewer flutes Titanium aluminum nitride (TiAlN) coating lubricates the end mill for high-temperature stability and abrasion resistance, offering better heat resistance than TiN and TiCN coatings Carbide can run at higher speeds than high-speed steel, resisting abrasion and high cutting temperatures Ball nose end mills (also called ball end) create contoured surfaces Center-cutting design allows the end mill to plunge into material like a drill bit while also performing conventional surface milling