Relative Significance of Multiple Parameters on the Mechanical Specific Energy and Frictional Responses of Polycrystalline Diamond Compact Cutters

A high pressure single polycrystalline diamond compact (PDC) cutter testing facility was used to investigate the effect of five factors on PDC cutter performance on Alabama marble. The factors include: depth of cut (DOC), rotary speed, back rake angle, side rake angle, and confining (wellbore) pressure. The performance is quantified by two parameters: mechanical specific energy (MSE) and friction angle. Fractional factorial design of experiments methodology was used to design the experiments, enabling detection of potential interactions between factors. Results show that, in the range tested, the only statistically significant factor affecting the MSE is DOC. In other words, DOC's influence is predominant and it can mask the effect of all the other factors. These results could have applications in real time pore pressure detection. Further, the results show that back rake angle is the most statistically significant factor in friction angle. Side rake angle and depth of cut also affect the friction angle, but in a relatively unimportant manner. The MSE–DOC behavior is explained and modeled by cutter edge–groove friction and the circular cutter shape. It is speculated that high cutter edge friction overwhelms the actual cutting process. A comparison of five currently present models in the literature with these results is presented and the conclusion is that the future PDC cutter models should digress from the traditional shear failure plane models.