Right from the start, Production Manager Dipl.-Ing. Achim Hoch was aware of the portal machining centre, which in his experience is "a workhorse that you can always rely on." "When machining crankcases on a horizontal drilling rig, we always had to reclamp them several times and move against the angle," recalls Hoch. "However, each additional reclamping process led to faults. And finally, after an informative visit to the Munich BMW tool shop which had several Droop+Rein portal machining centres, we decided to invest in this machine."

Technician Jürgen Seek, who was working on a 45-tonnes crankcase made of ductile cast iron (GGG 40) during our visit, is also satisfied with this investment. "Thanks to the use of ceramic tools, we can largely manage without coolant," Seek explains about the dry machining process. He is glad he no longer has to reclamp the workpiece multiple times. The gigantic component is machined in three steps: After milling the lower, lasered surface, Seek rotates the housing by 180° to allow the bottom of the housing to be machined. He then turns the GGG 40 component back to its initial position for complete machining. 

Although it sounds hard to believe, this is a routine job for the machinist. "The machine can do much more," he explains to us. "We've never been able to really wear it out — not even when even test-machining titanium."But what has been his most difficult job so far? Seek thinks for a moment and then says: "Retrofitting a 27-tonnes crankcase was extremely complicated. The crankcase, which was not assembled, was very unstable and difficult to clamp. Yet despite these unfavourable conditions, we had to machine it exactly to hundredths of a millimetre."

The NEA GROUP has not regretted their decision. The investment has paid off because, depending on the size, the machining time has fallen by an average of 30 to 40%, and accuracy has doubled even in critical areas. Tolerance in the bearing race is now only 20 µm instead of 40 µm. 

Starrag checks the geometry completely every two years and realigns it if necessary. Prell: "So far the realignment has been to such a small degree that we could actually go without it. This unusually high permanent accuracy benefits us, for example, in retrofitting work with a high proportion of machining." To ensure that even such demanding jobs are performed with precision, the NEA GROUP measures the components using complex 2D and 3D laser technology. 

In eight years of continuous operation, there has not been a single failure, with Starrag only having to replace the ball spindles once. According to Prell, this replacement is not unusual with operations where "we often have to move the moving crosshead". While he and his team have rarely seen Starrag service technicians, the department manager has always been satisfied with their very high-quality work. "We have a permanent contact who knows us well," says Prell. "You can see that there is a good communicative relationship between our employees and the Starrag service."   

But can satisfaction with the Droop+Rein T series portal milling machine be substantiated and summarised? "As a typical single-part manufacturer of classic German mechanical engineering with small batch sizes, it's difficult for us to name specific production improvements," says Hoch, Production Manager. "Furthermore, how long the machining process takes is not the most important thing for us. We prioritise quality and the portal milling machine is excellent." "The machine does exactly what we hoped it would," adds Prell. "So far we haven't exceeded the limits of its abilities." With that, he confirms and describes Starrag's claim "Engineering precisely what you value".