F-35 Aluminum Composite Stack Drilling

Lockheed Martin Aeronautics Company LMAC, Fort Worth, Texas, is experiencing issues when drilling advanced aluminum composite stacked skin material for the F-35 Joint Strike fighter JSF. The current tooling drill requires slower feed rates than desired due to the necessity of drilling through air gaps between the composite and aluminum stacks. Chip evacuation during the drilling operation also is an issue chips can get trapped within the air gap between the two material stacks and erode the composite material on the exit side of the hole. The current tooling also creates higher drilling forces than desired by LMAC. LMACs demands are increasing for the drilling of the aluminum composite stacked material used in the forward fuselage and wing assemblies on the F-35 JSF aircraft. Therefore, LMAC called upon the National Center for Defense Manufacturing and Machining NCDMM to lead a collaborative effort to research various drill geometries that would result in a more efficient solution for drilling these components to the specifications required by LMAC.