The physics of the micro-cutting process at very small depths of cut (1 mu m or less) is not well understood despite the successful development of ultra-precision machining technology. Sliding along the clearance face of the tool due to the elastic recovery of the workpiece and plowing due to the tool edge radius may become important in the micro-cutting range. To obtain a clear understanding of these two factors, an orthogonal cutting model, the so-called RECM (round-edge cutting model), is suggested.