glass spheres prepared by flame melting 2-mm glass rods in a butane-oxygen

While the separation rate is simply given by the piezoelement movement divided by the period of the run (assuming linear piezoelement movement), the contact time of the two surfaces is much harder to control. It depends on the location of point 2 (i.e. on the initial separation of the surfaces) and on the strength of any adhesion (corresponding to the length of the constant compliance region after point 4 in Fig. 1). Thus one of the parameters potentially controlling the dynamic adhesion is itself a function of the adhesion.