A new turning and milling centre for steam turbine rotors is said to be able to halve the manufacturing time, writes Kelvin Ross

Doosan Škoda Power has unveiled a new turning and milling centre for turbine rotors which it claims is unique in Europe.

The Czech Republic-based company has invested $7.1m in the centre which was built by German family firm GEORG.

And Doosan believes the new machine will now halve the time the required for rotor manufacture.

Jaroslav Milsimer, turbine division head at Doosan Skoda Power, says: “Up to now, turbine rotors have gone through three stages of manufacture.

“First, all the rotating planes of the rotor were turned, then the suspensions for attaching blades were milled, and in the last step apertures for balancing and couplings were drilled. Three different machines on three different work sites were needed for these operations.”

'Georg' in operation at Doosan Skoda Power's premises
‘Georg’ in operation at Doosan Skoda Power’s premises at Plzen in the Czech Republic

However, now Doosan Skoda says the new machine, which has been nicknamed Georg after its manufacturer, is capable of performing the three basic machining operations on its own.

Milsimer says: “Machines capable of doing both operations – unlike the history of separate turning and milling – have been developed on the market for a long time. Thanks to its accessories, for example the cutter head and the lathe chuck, Georg is able to turn 30 per cent quicker compared with our old equipment.

“It can even perform drilling and milling up to 50 per cent quicker, thanks to which the total time for making an average rotor is reduced from approximately 1000 to 550 hours.”

Although Georg is a colossus weighing tens of tonnes, just one person is needed to operate it during a shift. “One of the reasons is that the operator can comfortably watch the entire cutting process with the help of three internal cameras,” says Milsimer.

The machine, which is more than five metres tall, 30 metres long and ten metres wide, is sunk in a massive concrete foundation pit and the axis of the rotor’s rotation is positioned at the level of the operator’s eyes thanks to the ergonometric design of the machine, which is operated from the floor level.

There are only two such modern large GEORG machine tools in Europe – one in Germany and the other in Russia.

The machine was transported to Doosan Škoda Power’s Plzen premises disassembled, and was gradually reassembled in less than two months. It took another four months or so for the engineering specialists of the GEORG family firm to ‘bring the machine to life’; they fine-tuned the equipment tie-ins and carried out test measurements, and then compensated geometrical inaccuracies.

Although the machine is primarily intended for rotor manufacture it can be used universally.

“We can make any rotating component with a size of up to the working space, such as rotors for generators, rollers for paper mills, large-diameter gears including hubs and also, under certain conditions, crankshafts. In addition, we can drill or mill any number of any apertures on such components,” says Milsimer.