Orbital drilling speeds aircraft assembly

Sept. 21, 2005
Tool company and drilling machine supplier develop a special tool for burr-free holes.
Kennametal Inc., Latrobe, Pa., has partnered with Novator AB, an orbital-drilling-machine company in Spanga, Sweden, to marry that company's orbital-drilling expertise with the proprietary high-performance tools of Kennametal. The results of this partnership could cut the cost and time of assembling commercial aircraft in half. Typically, aircraft/aerospace shops drill innumerable holes in alloys or composite materials. However, traditional push-drilling, which involves driving drill points through either aluminum or stacks of laminated materials, creates burrs or delamination in exit holes and within the laminated stacks. Because of this, manufacturers must assemble parts, drill holes, disassemble parts, clean and deburr holes and then reassemble parts prior to final fastening. Also, specific tool sizes determine hole size, so many tools are required. And such tools can only be reground a limited number of times. Novator's orbital-drilling technology combines the spinning of a drill on its own axis with a mechanical spindle that rotates eccentrically around a principal axis. These dual high-speed rotations essentially feed tools through material rather than pushing them. This process eliminates stationary tool centers and, thus, reduces axial forces, as compared with conventional drilling. The tool's cutting edge only partially and intermittently engages with material surfaces, so heat build-up is minimal. Orbital motion also allows for tool diameters smaller than holes for efficient chip and heat extraction. Furthermore, one tool creates different diameter holes, which reduces tool inventory and tool management. Kennametal has developed a series of high-performance tools with proprietary geometries, substrates and coatings specifically for Novator's orbital-drilling machines. By joining forces, both companies believe they cover all aspects of holemaking in aircraft assembly, including process design, optimization, run-off and supply-chain management in a cost-effective way with maximum return on investment. (