The space tool radius offset G instructions with the developed approach will avoid NC codes regeneration due to tool wear or tool change during the three-axis NC flank milling process.

Comparing radius change of workpiece with limitation real time , at the same time taking into account the result of tool wear model to decide whether send offset signal to machine tool or not.

The paper presents tool offset in the process of CNC lathe machining, and expounds computational method of tool offset when CNC lathes do not possess the function of tool-radius offset.