Whether a tool needs to be coated or not depends on the material to be machined. Coated end mills are suitable for use on steel parts, which can significantly improve cutting performance and allow for greater machining parameters. Coated tools have the advantage of higher hardness, better chip removal and longer tool life. The most common coatings are titanium nitride (TiN), titanium carbonitride (TiCN) and aluminum titanium nitride (AlTiN).