Browsing by Keyword "Hole quality"
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Item Evaluation on advantages of low frequency assisted drilling (LFAD) aluminium alloy Al7075(2020) Veiga, Fernando; Suárez, Alfredo; Del Val, Alain Gil; Penalva, Mariluz; de Lacalle, Luis Norberto Lopez; Tecnalia Research & Innovation; FABRIC_INTELDrilling operation of dissimilar stack materials is a crucial assembly operation in airframe manufacturing; this is due to both the number of holes drilled in an aircraft structure and the fact that this is an operation performed in the finishing phase of the manufacturing chain. This paper aims to evaluate an alternative strategy for conventional drilling and peck drilling, which are now the most widespread solutions used for drilling aluminium alloys. The alternative approach proposed by this paper consists of low frequency assisted drilling (LFAD) performed into frequencies vibrations (between 50 to 100 Hz). In this paper, the chip formation process of drilling assisted by low-frequency vibrations of FC/Al stack material has been analytically modelled and compared with the conventional drilling of aluminium. Results show chip segmentation during the drilling operation resulting in less temperature increasing, avoiding problems in the final geometrical quality of the hole, and burr formation.Item Experimental Investigation of the Influence of Wire Arc Additive Manufacturing on the Machinability of Titanium Parts(2020-01) Alonso, Unai; Veiga, Fernando; Suárez, Alfredo; Artaza, Teresa; Tecnalia Research & Innovation; FABRIC_INTELThe manufacturing of titanium airframe parts involves significant machining and low buy-to-fly ratios. Production costs could be greatly reduced by the combination of an additive manufacturing (AM) process followed by a finishing machining operation. Among the different AM alternatives, wire arc additive manufacturing (WAAM) offers deposition rates of kg/h and could be the key for the production of parts of several meters economically. In this study, the influence of the manufacturing process of Ti6Al4V alloy on both its material properties and machinability is investigated. First, the mechanical properties of a workpiece obtained by WAAM were compared to those in a conventional laminated plate. Then, drilling tests were carried out in both materials. The results showed that WAAM leads to a higher hardness than laminated Ti6Al4V and satisfies the requirements of the standard in terms of mechanical properties. As a consequence, higher cutting forces, shorter chips, and lower burr height were observed for the workpieces produced by AM. Furthermore, a metallographic analysis of the chip cross-sectional area also showed that a serrated chip formation is also present during drilling of Ti6Al4V produced by WAAM. The gathered information can be used to improve the competitiveness of the manufacturing of aircraft structures in terms of production time and cost.