Abstract: Firstly this paper demonstrates in theory that the insulation status of machining system (especially workpiece) has almost no effect on the result of measuring the thermal E. M. F. fundamentally. Then the conclusions have been examined by series experiments which were performed on an engine lathe. In the application range of production engineering it would be good enough to pick up the cutting thermal E. M. F. signal without insulation of work and tool from machine-tool.

Key words: 加工系统的绝缘状态, 切削热电势