Ribs and frames are the elements that shape the structure of an aircraft wing. The ribs attach to the main spar, and through being repeated at frequent intervals form a skeletal shape for the wing. Ribs usually incorporate the airfoil shape of the wing, and the skin adopts this shape when stretched over the ribs.
These kinds of components normally start from an aluminium block or a pre-shape. As a huge amount of material has to be removed, we need a machine that is capable of performing at the levels the industry requires.
The other aspect of the process involves the fixture and tools. The former has to be as rigid as possible and the latter have to be specifically designed for this kind of operation, i.e. chip evacuation channel, sharpness, unequal helix, balancing, etc.
The 120 kW spindle
Aluminium cutting requires raw power and speed. That is what Makino's MAG spindle delivers: 120 kW of continuous power at 33,000 rpm. The roughing power of this monster can help a manufacturer achieve am MRR of over 8 litres per minute.
End mill - diameter 25 - MRR: 8,000 litres/minute (continuous)
End mill - diameter 25 - finishing at 50,000 mm/minute
The evolution of wing ribs
Although the external design of planes is mostly similar, the changes they have gone through internally have been radical. In order to increase stiffness, pockets have been made smaller, "T" and "I" type stiffeners added to the walls and honeycomb pockets added to locally reinforce components.
The required machine tools are also evolving, with the Makino MAG3.EX the best example. Its speed has been improved to up to 60 metres/minute and the new 130 kW spindle has more than three times the jerk of the previous model – a real reference in its class.
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