Framework for evaluation of the relative contribution of the process on porosity–cutting force dependence in micromilling of titanium foams

Abstract

Porous titanium, characterized by interconnected and large open-cell structures, constitutes one of the most promising bone substitutes that are currently available for surgical orthopedic and dental implantation procedures. Since little is known about the behavior of this highly porous material during material removal operations, the main objective of this study was to develop a framework capable of evaluating the effect of cutting speed, cutting depth, and feed rate on the interplay between porosity and cutting force signatures, as experienced during microslot cutting experiments. The comparisons performed between optically determined porosity and cutting force profiles by means of standard random data analysis metrics (correlation coefficient, power spectral density, and coherence) revealed that the presence of a material discontinuity has a prevalent effect on cutting force variation in the case of micromilling processes characterized by (1) less intensive machining regimes and (2) larger cutter/workpiece engagement zones. The proposed methodology is useful in selection of the investigative approach to be taken in assessment of the micromachining-related behavior of highly porous foams subjected to micromilling operations.