PSI - Issue 53

R.D.F.S. Costa et al. / Procedia Structural Integrity 53 (2024) 376–385 Costa, R. D. F. S. / Structural Integrity Procedia 00 (2023) 000 – 000

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Fig. 7. Chip morphologies in multi-material type I (a) and II (b). Chip with the two materials adhered (c).

Figure 8 reveals the drills’ superficial condition after dri lling 345 holes for each type of multi-material. In type I (a and b), for a combination of feed and cutting speed parameters of 0.05 mm/rev and 300 m/min., respectively, it is observed that some abrasive wear is present at the drill ’s corner , in the region where its main and the secondary cutting edges unite , due to the two CFRP layers’ abrasiveness. In type II (c and d), on the contrary, for a parameter combination of 0.2 mm/rev. and 150 m/min., no noticeable wear was observed other than a thin layer of built-up edge, formed through an accumulation of material in the drill’s blades and cutting edges , which was easily removed after the tests, leaving its surface below unaltered. In the last case, as only one composite layer was present in the second type of multi-material, no significant wear was found, but even in the first case the observed wear was not prominent, which makes it possible to conclude that drill 2 had an effective result in the drilling campaigns. Tool wear, although being higher in uncoated tools, also is a matter of concern in coated drills, as proven by the studies of D’Orazio et al. (D’Orazio et al., 2017) and Nurhaniza et al. (Nurhaniza, Ariffin, Mustapha, & Baharudin, 2016), which also experienced wear for higher feed values in their tools with different diamond coatings.

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Fig. 8. Tool wear assessment in drill 2 after 345 holes drilling campaign on multi-material type I (a, b) and type II (c, d).

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