Abstract: Introduces a NC machining of the steam turbine’s helical steam seal and the realization processing process,through the analysis of parametric model conversion,ingenious use of the commands frame system,the programming and production efficiency are improved, the processing quality is guaranteed, the molding tool preparation cost is reduced, and the molding production and repair for knife the grinding production preparation cycle is shortened.

Key words: helical steam seal in the inner circle of steam turbine, reduction construction of mathematical model, framework directive