Аннотация:In this report, a driven rotary tool’s machining performance on SUS304 stainless steel was examined. The rotary tool was attached to a milling axis on a multi-tasking lathe which has B axis control. It is possible to adjust the tool‘s circumferential speed as the tool is controlled to rotate by a milling motor. As well, the contact angle between the work-piece and cutting point are controllable as the milling axis has four degrees of freedom of movement. The objective of this study was to clarify the influence of tool posture on the rotary cutting process. It was found that when the tool inclination angle increases, the tool temperature increases and the chip flow angle increases.