An experimental investigation was conducted to examine the dissipation of mechanical energy when machining at depths of cut less than several micrometers. Cutting and thrust forces which resulted in the orthogonal ultra-precision flycutting of Al 6061-T6 were measured over a range of depth of cut of 20 μ-m down to 0.01 μm at a cutting speed of 0.8 m-sec−1. Measurement of the tool-workpiece contact length indicated that it may become the characteristic length scale when machining al submicrometer depths of cut. Evidence suggests that the process may be viewed as transitioning from a cutting-dominant to plowing/sliding indentation-dominant process. Tool edge condition was seen to have a significant effect on the resulting forces when the depth of cut was below the tool edge radius.Presented as a Society of Tribologists and Lubrication Engineers paper at the STLE/ASME Tribology Conference in New Orleans, Louisiana, October 24–27, 1993