Coated cutting tool with an alternating layer composition

A coated cutting tool comprising a substrate and a coating, the coating comprising a (Ti,Al, Si)N layer wherein the (Ti,Al,Si)N layer has a periodical change in contents of elements Ti, Al, and Si, over a thickness of the (Ti,Al,Si)N layer, between a minimum content and a maximum content of each element, wherein

• an average minimum content of Ti, over the entire thickness of the (Ti,Al, Si)N layer, is a value within a range of from 14 to 18 at. %,
• an average maximum content of Ti, over the entire thickness of the (Ti,Al, Si)N layer, is a value within a range of from 18 to 22 at. %,
• an average minimum content of Al, over the entire thickness of the (Ti,Al, Si)N layer, is a value within a range of from 18 to 22 at. %,
• an average maximum content of Al, over the entire thickness of the (Ti,Al, Si)N layer, is a value within a range of from 24 to 28 at. %,
• an average minimum content of Si, over the entire thickness of the (Ti, Al, Si)N layer, is a value within a range of from 0 to 2 at. %,
• an average maximum content of Si, over the entire thickness of the (Ti,Al,Si)N layer, is a value within a range of from 1 to 5 at. %,
• the average minimum content and the average maximum content of the elements Ti, Al, and Si, are determined by taking at least eight consecutive minima/maxima from an elemental analysis and calculating an average,
• a remaining content in the (Ti, Al, Si)N layer is a noble gas with an average content of from 0.1 to 5 at. % and the element N,
• an average distance between two consecutive maxima in content, and between two consecutive minima in content, over the entire thickness of the (Ti,Al, Si)N layer, of any of the elements Ti, Al, and Si, is a value within a range of from 3 to 15 nm, the average distance being determined by taking at least eight consecutive maxima/minima from an elemental analysis and calculating an average value,
• in a periodical change in contents of the elements Ti, Al, and Si over the entire thickness of the (Ti,Al, Si)N layer the maximum content of Ti, the minimum content of Al and the minimum content of Si coincide in average over the entire thickness of the (Ti,Al, Si)N layer, and the minimum content of Ti, the maximum content of Al and the maximum content of Si coincide in average over the entire thickness of the (Ti,Al, Si)N layer, there is an average gradual change in contents of Ti per distance over the entire thickness of the (Ti,Al, Si)N layer, between a minimum and a maximum content, and between a maximum and a minimum content, which is a value within a range of from 0.8 to 1.5 at %/nm, an average gradual change in contents of Al per distance over the entire thickness in the (Ti,Al, Si)N layer, between a minimum and maximum content, and between a maximum and minimum content, which is a value within a range of from 0.8 to 1.5 at %/nm, and an average gradual change in contents of Si per distance over the entire thickness in the (Ti,Al, Si)N layer, between a minimum and maximum content, and between a maximum and minimum content, which is a value within a range of from from 0.3 to 0.8 at %/nm, the average gradual change in contents of the elements Ti, Al, and Si, respectively, per distance over the entire thickness in the (Ti, Al, Si)N layer, is determined by subtracting an average minimum content (at %) from an average maximum content (at %) of the Ti, Al, and Si elements and dividing the resulting value by the average distance between the position of a maximum and a position of a minimum content of the Ti, Al, and Si elements in the (Ti,Al,Si)N layer, at least eight consecutive maxima/minima from an elemental analysis are being taken into account.