Abstract
A full factorial experimental design involving single-shot drilling of 3 layer Ti-6Al-4V/CFRP/Al7050 stack workpieces was performed to evaluate the effect of drill geometry (single and triple margin), feed rate (0.05 and 0.08 mm/rev) and operating strategy (with and without pecking) on burr formation and hole surface integrity. All tests were carried out wet using twin-fluted, coated tungsten carbide drills having a diameter of 6.35 mm. When employing triple margin drills, average hole surface roughness (Ra) values were 2.20, 9.66 and 0.83 μm in the Ti, CFRP and Al sections respectively at test cessation (90 holes). These were 4 times higher for the Ti and Al layers compared to those produced with the single margin geometry. Similarly, an increase in Al entrance and exit burr heights of ~100 and ~430% respectively was observed when employing triple margin drills due to the greater contact area between the tool and workpiece. However no delamination of the CFRP layer was detected in any of the holes machined with the triple margin tools. Cross-sectional microstructures of Ti and Al layers showed plastically deformed regions of up to 184 and 75 µm respectively beneath the machined surface. Corresponding microhardness evaluation of the Ti section showed an increase of up to 60 HK0.025 above the bulk value, to a depth of ~200 µm.
Original language | English |
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Title of host publication | Proceedings of the 30th International Manufacturing Conference (IMC30) |
Editors | Gerry Byrne, Brid Mullaney, Pat Connolly, Eamonn Ahearne, Naomi Green |
Publisher | University College Dublin Press |
Pages | 104-113 |
Number of pages | 10 |
ISBN (Print) | 978-1-90-525475-0 |
Publication status | Published - 1 Sept 2013 |
Event | International Manufacturing Conference, 30th (IMC30) - University College Dublin, Dublin, Ireland Duration: 3 Sept 2013 → 4 Sept 2013 |
Conference
Conference | International Manufacturing Conference, 30th (IMC30) |
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Country/Territory | Ireland |
City | Dublin |
Period | 3/09/13 → 4/09/13 |
Keywords
- Ti/CFRP/Al stacks
- drilling
- surface integrity