Abstract
High precision drilling is required to ensure the structural integrity of the aircraft. Therefore, strict quality controls are required to ensure optimum hole quality since hundreds of thousands of holes are drilled into different aircraft structures. The large number of holes required for riveting means that their installation must be carried out in a fast and precise manner. This can be achieved using multi-head drilling tools that can drill several holes simultaneously. The current study investigated the use of a multi-spindle drill head that can produce three holes simultaneously. Uncoated carbide and TiAlN-coated and TiSiN-coated carbide drills were used to assess cutting forces, hole surface roughness, burr formations and tool condition when machining Al2024 aerospace alloy under dry machining conditions. Analysis of variance was employed for estimating the relationships between the input parameters (spindle speed, feed and tool coating) and the studied hole quality metrics. Furthermore, a regression model was developed with a regression coefficient (R2) of more than 90% for the prediction of measured responses. Interestingly, better results in lower thrust force and surface roughness were obtained using the uncoated carbide drills compared with TiAlN and TiSiN, while the performance of TiAlN was found to be better than those obtained from TiSiN.
Highlights
Riveting which is achieved by hole drilling, is the most common method used for the assembly of aircraft structures
In the Chemical vapour deposition (CVD) technique, thin films are deposited on the cutting tools through various chemical reactions, whereas the physical vapour deposition (PVD) technique includes the deposition of the thin film on the tools through a physical technique such as sputtering and evaporation [7]
Dumkum et al [15] reported that the TiAlN gave the lowest surface roughness and smallest tool wear while TiN-coated drills resulted in the lowest thrust force and torque
Summary
Riveting which is achieved by hole drilling, is the most common method used for the assembly of aircraft structures. The contact between the cutting tool and the chip during the drilling process can promote thermal and mechanical stresses, which can increase the surface roughness in the hole. High productivity is achieved at a high cutting speed that associates a large amount of heat which might increase the power consumption, and subsequently, the cutting force increases [7] In this regard, coatings on the tools have been introduced to increase the life of the tool, reducing the manufacturing cost due to less frequent tool changes [8]. This study investigates the effect of cutting tool coatings (TiAlN- and- TiSiN) on the machinability of Al2024 using the multi-hole simultaneous drilling approach, which has received less attention from researchers. The selection of suitable tool material together with the use of multi-hole drilling would further enhance productivity in any manufacturing industry
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