The Effect of Cryogenic Cooling and Drill Bit on the Hole Quality when Drilling Magnesium-based Fiber Metal Laminates

Abstract The interest on fiber metal laminates has increased significantly in recent years as a consequence of the request of lighter and more functional aerospace and automotive components. In such parts, drilling is essential for assembly purposes. Nevertheless, drillability of fiber metal laminates is a critical issue due to the heterogeneous mechanical and thermal properties of metals and composites. The current research work aims at understanding how to improve the hole quality after drilling of magnesium-based fiber metal laminates. To this aim, dry and cryogenic cooling was applied as well as the adoption of three different drill bits, namely uncoated drill bits, coated drill bits and spur drills. Hole size, cylindricity, roughness, entry burr height, exit delamination and fiber pull-out are considered as experimental outcomes to characterize the hole surface quality. Results show that both spur drills and cryogenic cooling can significantly improve hole quality. The process parameters combination capable to guarantee the highest surface quality is finally provided