Abstract
In machining it is a basic theme to make a wide plane accurately. For this purpose a milling machine is used, however, it is usually difficult to obtain good plane because of presence of stair between neighboring cutter passes and of tendency of concavity even in one cutter pass. The study aims at evaluating such machining errors in face milling. Considering that the deformation of machine tool due to cutting force and the thermal expansion of tool cause machining error mainly, the analysis was made provided that by using a face milling machine with relatively good geometrical accuracy machining is done within a short time the thermal deformation of machine tool structure has nothing to do with. Predicted values of machining error from data about machine tool structure and cutting condition correspond to measured ones in cutting experiments quantitatively. As a result it becomes apparent that the obliquity of cutter axis owing to deformation of machine tool structure by cutting force causes the concavity of plane and that the change of cut of depth due to thermal expansion of tool shapes stairs between neighboring passes.
