MASTER OF PRECISION

At the turbomachinery production site in Oberhausen,  a skilled workforce makes every  micrometer count.

Meters-high machines are closely spaced as far as the eye can see in the huge MAN Diesel & Turbo production site in Oberhausen. The sound of metal being worked permeates the space where several hundred production specialists are at work. At its turbomachinery works in Oberhausen, Germany, MAN Diesel & Turbo develops and manufactures compressors, turbines and complete machinery trains for the various needs of the industry worldwide.  This includes in-house manufacturing of many components as well as their assembly to a ‘inished machine or train.

“We manufacture individually according to very specific customer needs, which means that we often have a batch size of just one,” explains Dr. Carsten Achtelik, Head of Production in Oberhausen. “And that we have only one shot to get it right.”

Precision is key

Precision is, accordingly, key – and so is the workforce on this 70,000-square-meter site. Despite hundreds of special machines, it is experienced employees who render the last quantum of quality possible – for example, by choosing the ideal processing method. Where every-thing may depend on accuracy down to the micrometer, experience is invaluable.

“We have to be able to guarantee our customers certain levels of efficiency and performance for the machinery we manufacture, which is why have to work within very narrow tolerance ranges,” explains Achtelik. This is true of small components and also of large ones, such as the rotor of a 100 MW steam turbine. These may measure several meters in diameter and can weigh 20 or 30 metric tons. When they are in use at 5,000 rotations per minute, precision needs to be up to a hundredth of a millimeter. And that for many years, as the final products, worth some million euros each, are in operation for decades. 

High precision 

One of those experienced specialists is Wolfgang Rau. He has been working at the MAN site for 30 years. The CNC machinist is standing next to a digitally controlled chipping machine and attentively supervises how the machine slowly turns its program sequence into a high-precision contour of the metal. If a measured value does not match, Rau has to make a decision. “We manufacture so individually that serial production is possible only within very narrow limits,” explains Rau.

And so the machine-driven execution is still strongly supported by the experience of the production workers. For example, inserting the blades onto a shaft, to finally create a rotor: Each blade is manufactured individually on a high-tech machine in the same production hall, some meters away. The insertion into a notch in the shaft takes up to five minutes each, depending on the blade size.

Besides all high-tech processes here, this step is executed by the workers by hand, converting their experience into quality. “This step, demanding flexibility and a high level of experience, could not be done by a machine,” says Abdullah Onur, who is one of the specialists for that task. “The requirements of that operation are so individual that it would be nonsensical to apply a robot here.” Clearances have to be checked, and occasionally adaptions to a row of blades have to be made.

Once a blade is inserted, Onur and his colleagues immediately can tell whether they are sitting properly – to the hundredths of a millimeter. The turbomachinery coming out of Oberhausen has to perform for decades while withstanding immense stresses. A gas turbine blade, for example, is exposed to temperatures of more than 1,200°C, enduring pressures between 10 to 15 bar. Next to high-tech materials employed, it is this accuracy in production that guarantees MAN Diesel & Turbo’s customers longevity and efficiency of their turbomachinery.  

Profound knowledge is required

To training supervisor Thomas Wischermann, the human factor is crucial when working with the machines: “To know how the machine works, our experts have to have a profound knowledge of materials, for example. This is why apprentices in their first year also learn how to rasp by hand, so they internalize a feeling for these metals.” That is why MAN Diesel & Turbo puts a strong emphasis on training their own personnel.

Currently, 85 apprentices are working in the practice area. Even after completing their apprentice-ship, it will take a few more years before they have gathered the necessary experience. “Having to work according to the ‘first time right’ principle puts a great emphasis on our production crew,” explains Carsten Achtelik. “It takes years to get the kind of experience to be able to confidently manufacture a part with the needed precision in just one go.”