Drilling analysis of thin woven glass-fiber reinforced epoxy‎ composites

In this study, the influence of cutting speed (16.3, 32.7 & 65.3 m/min) and feed (0.025-0.1 mm/rev) on cutting temperature, thrust ‎force, torque, delamination factor, surface roughness and bearing strength in drilling thin woven glass-fiber reinforced epoxy (GFRE) composites was investigated, for the first time, grouped in one article. The results of drilling tests showed that the thrust force (Ft), torque, and delamination factor are increased with increasing feed and vice versa for the induced temperature. Drilling of GFRE composites at lower speed (16.3 m/min) result in lower temperature rise, higher thrust force, higher torque and accordingly, higher delamination factor compared with that drilled at 65.3 m/min. Drilling at temperature close to glass transition temperature is useful for reducing Ft, delamination and thus obtaining better bearing strength compared with drilling at lower temperature levels. The critical thrust force at the onset of push-out delamination was predicted for different uncut layers, in front ‎of the drill chisel edge, using some analytical models.‎ For the first time, in drilling [0°]8 woven composites, the [ABD] stiffness matrices was effectively ‎represented by [0°/90°]4s cross-ply laminate with the advantages that the elastic properties were determined by the rule of mixtures (no need to perform ‎mechanical tests).