Nanomachining experiments on fused quartz surface have been performed using an atomic force microscope combined with a two-axis capacitive force/displacement transducer. The minimum normal force fnP needed to form reproducibly a groove was about 4.7 μN. The minimum critical normal force fnR, tangential force ftR, and groove depth dgR when the material removal process began were found to be 33.7 μN, 18.7 μN, and 4.3 nm, respectively. Characteristic changes in the swelling ratio Rs and the ratio of force components at the critical normal force fnR can be used to identify the critical condition for changing from plastic deformation to material removal process region
