energy

Blisk machining of a complex turbine component

When it comes to machining a particular component of a turbine, there is now a new development to consider: the Starrag NB 251, a machine tool specially developed for the complete machining of blisks/IBR.

The NB 251 is capable of performing all relevant production steps: from the efficient roughing of components from a single piece of material to the adaptive machining of friction-welded blisks, right the way through to the highly dynamic smoothing of flow surfaces in point contact.

Now, discussions are centring around the Starrag NB series, which has been developed and optimised with the process as a whole in mind – that is, the highly efficient, simultaneous five-axis machining of blisks/IBR.

A prime example of a machine in this series is the NB 251 with an inclined B axis, on which the tool is practically rotated around the tool centre point. The compact design of this machine is characterised by its extremely high degree of machining accuracy, high cutting performance and high level of dynamism with a low number of moving masses. Compared with a standard machine with swivel rotary table, the strengths of the NB 251 are obvious. When the rocker swivels, the machines with swivel rotary table needs extra time for the very long compensating movements. These compensating movements are necessary to ensure the tool remains on the same machining point.

The compact design of this machine is characterised by its high degree of machining accuracy, high cutting performance and high level of dynamism

The NB series (shown here in the form of an NB 251) has been developed for the highly efficient, simultaneous five-axis machining of “blade integrated disks” (blisks)

Tailor made: Starrag developed and optimised simultaneous five-axis machining back in the 1950s

“With the NB series, the tip of the tool is located very close to the centre of rotation. As a result, the compensating movements of the axes are five-times shorter”, Starrag Product Manager Michael Koller explains. “What’s more, the fact that the NB machines can also move and accelerate extremely quickly makes them significantly more dynamic”. Users can even achieve further increases in productivity in what is already a highly dynamic machine by using an NB 252. The “2” at
the end of the machine name indicates that the machine tool is equipped with two spindles. In effect, the NB 252 is two machines on a single machine tool bed – the spindles of these machines can simultaneously machine two completely different workpieces redundantly and independently of each other. Adopting this solution allows users to achieve a massive increase in productivity at significantly lower investment costs per work spindle. The outstanding performance characteristics are due to the fact that this new machine has also been developed and optimised with the process, output and level of dynamism and accuracy in mind.

+ 25% shorter cycle times due to signifi cantly shorter compensating movements of the axes
+ Doubled productivity due to the use of two spindles for the machining of two workpieces simultaneously

Titanium blisk of an aeroplane engine milled from solid material in a single clamping position.

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