CNC lathes can also be used as rough, finishing. In order to rough processing can be a larger depth of cutting, the greater the speed of processing, requiring rough cutting tool strength, durability is good. Fine car is to ensure the accuracy of processing, so the requirements of high precision tool, durability is good. In order to reduce the tool change time and facilitate the knife, should be more than the use of machine knife. CNC lathes also require a consistent blade durability, in order to facilitate the use of tool life management functions. When using tool life management, the blade durability setting principle is based on the blade with the lowest degree of durability in the batch. In this case, the blade durability is even more important than its average life expectancy.