Though composites are commonly molded for achieving near net-shape, they have to undergo precise machining in order to achieve the dimensional stability and an interface quality. A complicated interaction between polymer matrix and carbon fiber reinforcement makes the machining of the CFRP material a major concern. Due to this heterogeneous nature of the CFRP, the machined surfaces result in damages like delamination, spalling, and splintering. In order to minimize these damages, knowledge about tool replacement time or tool life is necessary. In this study an effort is made to determine the tool life for diamond interlocked knurled tool commonly used for machining CFRP material. Direct tool wear measurement techniques were inadequate to determine the tool life because of the complex geometry of this tool. Therefore, in this study indirect tool wear measurement technique is used to quantify the tool wear based on delamination. The damage caused by delamination on the CFRP material undergoing edge trimming operation is measured in the form of delamination depth as well as number of delamination occurrences per inch. The effects of experimental parameters on delamination depth as well as number of delamination occurrences per inch are observed to find optimized process parameters. An attempt is made to develop an empirical tool lie equation based on the combined effect of delamination depth and number of delamination occurrences per inch.