Microstructural investigation of drilling induced damage in fibre metal laminates constituents

Fibre metal laminates (FMLs) are used in the upper fuselage of the Airbus A380 aircraft. Machining FMLs might cause various forms of damage around the hole either in the composite layers or the metallic sheets, all of which are known as drilling-induced damage which deteriorates the surface quality of the metal/composite. The current study investigates the effects of cutting parameters on the drilling-induced damage during drilling of GLARE FMLs at a microstructural level. This study extends the previous investigation of our study on dry drilling of GLARE laminates by incorporating two modern cooling technologies namely cryogenic liquid nitrogen (LN2) and minimum quantity lubrication (MQL) to investigate their impact on drilling-induced damage in FMLs. The results showed that both cutting parameters had an impact on the drilling induced damage in the borehole, while using MQL and cryogenic coolants showed the ability to eliminate waste formation on the machined borehole surface.