Interfacial burr formation during through-hole drilling in stacked aluminum sheets is a common problem in aircraft assembly operations. Burrs formed at the interface of the sheets are removed through non-value added destacking and deburring operations that increase the overall assembly time and costs. This paper presents experimental work aimed at understanding the impact of drilling parameters including drill geometry, cutting conditions, clamping configuration and drill wear on interfacial burr formation. Specific conclusions regarding the influence of these parameters on burr sizes and drilling forces are presented. It was found from the drilling parameter experiments that interfacial skin exit burrs and frame entry burrs demonstrated a similar dependence upon all the examined parameters. Averaged across all tests, frame entry burrs were approximately 15% smaller than skin exit burrs. It was found that the most significant factors in interfacial burr formation were drill point angle, clamp type and clamping distance. A combination of a 118 deg point angle with a hole location near either a hand clamp or hole clamp reduced the interfacial burr heights. Additionally, the analysis revealed that smaller feeds produced smaller skin exit burrs, while the use of a step drill reduced the frame entry burr. It is believed that these trends will hold true for both types of interfacial burrs. The most significant finding in the drill wear experiments was that a step drill with a 118 deg point angle (Drill 1) produced the smallest interfacial burrs, including skin exit burr heights, frame entry burr heights, and skin exit burr widths over the useful life of the drill. This agreed with results found in the drilling parameter experiments. The drill wear experiments also showed that for Drill 1 the burr heights and widths over the complete range of 1500 drilled holes remained nearly constant rather than increasing with drill wear. Furthermore, measurements of drill wear showed that Drill 1 had similar or even lower wear rates than the other two drills. Therefore, the results indicate that Drill 1 (step drill) yields the best results as far as interfacial burr formation is concerned and is the preferred drill for minimizing the same.


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    Title :

    Interfacial burr formation in drilling of stacked aerospace materials


    Additional title:

    Trennflächengratbildung beim Bohren von gestapelten Luftfahrtwerkstoffen


    Contributors:
    Melkote, S.N. (author) / Newton, T.R. (author) / Hellstern, C. (author) / Morehouse, J.B. (author) / Turner, S. (author)


    Publication date :

    2009


    Size :

    10 Seiten, 17 Bilder, 2 Tabellen, 26 Quellen



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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