Delamination at the hole entrance and exit during drilling of the FRPs composites adversely affects the hole surface quality and engineering properties of this material. In this study, delamination occurrence in hole entrance and exit during drilling of carbon fiber reinforced carbon matrix composite material (C/C) as stacked on aluminium plate was investigated. According to Taguchi L-9(3(3)) orthogonal array test design experiments were conducted for each of with 90 degrees-118 degrees and 135 degrees point angle uncoated, TiN and TiAlN coated HSS drills. Three different cutting speeds (100-125-150 m/min) and feed rate (0.1-0.2-0.3 mm/rev) values were used as cutting parameters. The study showed that uncoated drills caused less delamination than TiN and TiAlN coated HSS drills and optimum cutting parameters were determined as the high cutting speed, low feed rate and drill point angle combination (V:150 m/min, f: 0.1 mm/rev, theta: 90 degrees). With ANOVA (Analysis of variance), the most effective parameter on hole entrance and exit delamination of the composite material was determined as the feed rate. First degree mathematical models were developed for entrance and exit delamination factors of each cutting tool using regression analysis. According to the obtained data, optimization, mathematical models and experimental test results were found very coherent. (C) 2020 Elsevier Ltd. All rights reserved.