A numerical and experimental investigation of the machinability of elastomers

In this dissertation, the machinability of elastomers is investigated. The main objective of the research is to determine the machining conditions for which an elastomer can be machined with a smooth surface finish. Both machining experiments and numerical simulations were carried out to achieve this goal. For the experimental studies, a series of orthogonal machining tests were conducted to investigate the effects of various machining parameters on chip morphology, machined surface condition, and resulting machining forces. Feed speed and rake angle were found to have a significant effect on the type of chip generated during orthogonal machining. High feed speed conditions and large rake angle tools produced long and continuous ribbon-like chips and a corresponding smooth machined surface. The design of the workpiece fixture in the lathe was also found to be critical for machining smooth surfaces.; In the numerical investigation, half-wedge indentation and orthogonal cutting models were developed to simulate incipient separation of elastomers. It was found that high tensile normal stress and maximum principal stresses, as well as a large concentrated strain energy density near the separation point lead to favorable conditions for the formation of continuous chips and a good surface finish. The indentation simulations correlated well with the cutting tests in which tools with a large rake angle and large feed produced continuous chips and a smooth surface finish. The models offer potential for identifying the cutting conditions and tools that produce a smooth machined surface finish of elastomers.