Comparative evaluation of machining processes for making holes in GLARE fiber metal laminates

Drilling is widely used in manufacturing industries for making holes in a variety of components. However, dissimilar material properties of fiber material laminates (FML) makes hole processing a challenge. Also, high thrust load damages the material thereby affecting the hole surface quality and dimensional accuracy. This work evaluates the conventional drilling and newer helical milling process for making holes in glass laminate aluminum reinforced epoxy (GLARE) FML. The processes were analyzed considering the machining forces, surface roughness, hole diameter, and machining temperature. Magnitude of the machining forces and temperature were lower in case of helical milling process and the surface finish was found to be better when the helical hole milling process was used. Hole drilling process resulted in the generation of long continuous chips which frequently entangled around the drill bit while the use of helical hole milling process resulted in the production of powdery discontinuous chips which helped in easy evacuation. In addition, the formation of burrs was noted during the drilling process while hole milling resulted in relatively burr-free holes.