An Investigation into the Use of Small, Flexible, Machine Tools to Support the Lean Manufacturing Environment

Drilling fastener holes in large assemblies is traditionally accomplished through the use of large machine tools in order to obtain the accuracies required for the assembled part. Given recent advances of machine design and machine controller compensation, the accuracy of the motion platform can be corrected if the machine is repeatable. This coupled with the use of a vision system or touch probe to compensate for assembly variations, permit the use of smaller, more portable drilling systems. These smaller, more portable machine tools allow for lean manufacturing techniques to be incorporated into build processes, utilize less floor space, and in many cases are less costly than larger, permanent machine tools. This paper examines the feasibility of utilizing a small 5-axis, portable, drilling system for drilling the side panel skins on the F/A-18 E/F forward fuselage. The system will have the capability to scan key-locating features on the assembly, correct for any assembly variations, and drill and countersink through various stack-ups of composite, aluminum, and titanium. The drilling system can be easily hoisted on and off of the existing assembly jig to allow for additional utilization of the assembly jig for other manufacturing operations. This paper will examine the technical aspects of the portable machine tool, along with the advantages and disadvantages of small portable drilling machines for the use in assembly processes.