Fundamental analysis of the cutting edge micro-geometry in orthogonal machining of unidirectional Carbon Fibre Reinforced Plastics (CFRP)

Abstract

Machining of carbon fibre reinforced plastics (CFRP) is closely related to strong abrasive tool wear and represents a significant process challenge due to its anisotropic material structure and brittle fracture behavior. Furthermore, machining of unidirectional CFRP material shows a significant increase in process forces due to tool wear effects, resulting in a changing micro-geometry of the cutting edge. This research work aims to give a detailed analysis of the tool wear behavior with respect to the five micro-geometry parameters based on an approach of “straight line–ellipse–straight line”, capable also to describe the developing asymmetric cutting edge. Therefore, fundamental orthogonal machining experiments with varying fibre orientations and tool geometries are conducted. It can be shown that the micro-geometry changes with increasing cutting length, whereby an increase of the resulting friction length and spring back height can be detected, having a significant influence on the process forces.