Tool with wear detection

A method of manufacturing a coated tool, comprising:

• applying a first undoped diamond layer over a functional surface of a tool body, wherein the first undoped diamond layer is applied using chemical vapor deposition (CVD) from an atmosphere of methane and hydrogen in a CVD chamber, wherein the first undoped diamond layer is electrically conductive, and wherein the first undoped diamond layer exhibits grain boundary conductivity from delocalized electrons;
• and
• applying a second undoped diamond layer over the first undoped diamond layer, wherein the second undoped diamond layer is electrically insulating, and wherein as the first undoped diamond layer is applied, a mass flow rate of the methane is maintained in a range of 75-105 standard cubic centimeters per minute.

A method of manufacturing a coated tool, comprising:

• applying a first undoped diamond layer over a functional surface of a tool body, wherein the first undoped diamond layer is formed using chemical vapor deposition (CVD) from an atmosphere of methane and hydrogen in a CVD chamber, wherein the first undoped diamond layer is formed without using doping gas, wherein the first undoped diamond layer is electrically conductive, and wherein the first undoped diamond layer exhibits grain boundary conductivity from delocalized electrons;
• and
• applying a second undoped diamond layer over the first undoped diamond layer, wherein the second undoped diamond layer is electrically insulating.