Niagara Cutter N77473 Cobalt Steel End Mill, General Purpose, TiAlN Coated, 4 Flutes, Square End, 32mm Cutting Length, 18mm Cutting 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 at high cutting speeds, offering better heat resistance than TiN and TiCN coatings Cobalt steel resists abrasion and high cutting temperatures, and has higher feed rates than high-speed steel Square nose end mills (also called square end) create sharp, unrounded cuts Center-cutting design allows the end mill to plunge into material like a drill bit while also performing conventional surface milling