High-speed steel the thread tool surface coating, which can effectively reduce cutting friction reducing tool wear, greatly improve the cutting disc cutting performance and service life (typically 2 to 3 times the tool life can improve). TiN coating and composite coating process in foreign threaded tool production has been widely adopted, such as the German GUHRINR, EMUGE the various coating products accounted for about 40% of the thread cutter production.

Hardness is one of the important parameters of high-speed steel threaded tool cutting performance. In the process of processing thread, the higher cutting heat generated and passed to the tool, so that the tool hardness decreased. According to the information, after cutting zone temperature exceeds 550 ° C, the microstructure tool will change, resulting in rapid decline in tool hardness; temperature is increased to 100 ° C, the hardness decreased up to 300 ~ 400 HV; if the abrasive tools hardness dropped 59 ~ 60HRC, will basically lose cutting ability. Thread cutter after the coated surface hardness can be significantly higher: TiN coating hardness up to 2300HV above; TiCN coating hardness up to 3000HV. Thread tool surface coatings with different features and different scope of application: high hardness after the TiCN coating of high-speed steel thread tool, can be achieved with uncoated carbide tool cutting performance; addition, in some cutting occasions, compared to the the TiCN coating high-speed wire cone with uncoated carbide tool has the advantage of low cost. Tap tapping cut yellow copper or aluminum workpieces TiCN coating, tool life can be increased by more than 10 times; the TiAlN coating tap-tapping cut gray cast iron or aluminum alloy workpiece hypereutectoid, tool life increased by 4 times or more. Compared with the TiN coating, TiAIN coating enables the tool has a higher hardness and better oxidation resistance, and therefore more suitable for high-speed machining TiAIN coated tool.