Neuman & Esser uses 8-year-old Droop Rein from Starrag as the "workhorse" for complete processing. #case analysis

The advantage of the Starrag Droop Rein T gantry machining center lies in complete machining. Depending on the workpiece, it can be machined with or without coolant. However, due to the use of high-strength materials, there is no need for trace lubrication. All photos are provided by Starrag/Ralf Baumgarten.

Large machine tools are a huge investment. Fortunately for Neuman & Esser (NEA), the benefits it gained from Starrag's Droop Rein proved equally impressive.

"Droop Rein is one of our best horses in the stables," said Alexander Peters, managing partner of NEA. "We are very satisfied with this machine, its performance and the service provided by the manufacturer."

He is talking about the Starrag gantry machining center with an adjustable beam and a movable clamping table. Droop Rein T 30 40 DT R50 C is currently the largest investment in machine tools in the history of the NEA Group. It has proven itself in processing demanding components, such as piston compressor components in compressor systems for processing technical process gases and Pendulum mill shell used in crushing technology.

"Since 2011, our gantry machining center has been in continuous operation," said Simon Prell, NEA Machinery Production Manager. "We mainly use it to machine crankcases and gaskets as part of a three-shift operation. These components prevent gas from escaping from the cylinder into the crankcase and prevent oil from entering the cylinder from there."

Simon Prell said that the exceptionally high permanent accuracy of the portal milling machine has benefited his company in applications such as retrofit work.

NEA also uses machine tools to produce crusher castings. This usually requires complete machining, which can be machined with or without coolant depending on the workpiece. However, due to high-strength materials such as steel alloys with a high content of nickel or chromium, a trace amount of lubrication is not required.

According to the company, Droop Rein was very popular even during the commissioning phase eight years ago. In fact, the company said that although it involves a completely new form of processing, this is one of the smoothest introductions it has ever experienced.

In 2011, NEA processed crankcases on a horizontal boring machine. One of the main problems with this method is the long unproductive time due to the time-consuming clamping process. In contrast, the gantry machining center only needs one clamping process, which greatly reduces the processing time of overweight workpieces. The crankcase can also be processed in its working position. According to Mr. Prell, one of the main advantages of gantry machines is that they can optimally position and align different processing heads.

According to production manager Achim Hoch, “When machining crankcases on a horizontal boring machine, we always have to re-clamp them several times so that the part surface is perpendicular to the spindle entrance. However, each additional re-clamping process All can lead to failures. Finally, after a lot of information visits to the Munich BMW tool shop with multiple Droop Rein gantry machining centers, we decided to invest in this machine."

The gantry machining center has two tables, each of which measures 118.1 x 157.4 inches. The X-axis movement path is 196.9 inches and 413.4 inches for each coupling, while the Y-axis and Z-axis movement are 177.2 and 68.9 inches, respectively. Other features include a channel width of 137.8 inches between the columns and a gap height of 137.8 inches between the table and the moving beam. The machine is controlled by Siemens Sinumerik C 840D, and the tool change is provided by an automatic change system with chain tool magazine and 80 storage spaces.

Technician Jürgen Seek is satisfied with this investment. "Because of the use of ceramic tools, we can largely process without coolant," he said of the dry machining process.

Mr. Seek said that he is happy that he no longer needs to re-clamp the workpiece multiple times. This huge part is processed in three steps: After milling the lower laser-detected surface, he rotates the housing 180 degrees in order to process the bottom. He then turned the ductile iron GGG-40 part back to its original position for complete machining.

Technician Jürgen Seek said that the functions of the portal milling machine exceed those currently used by Neuman & Esser.

"This machine can do more things," he said. "We have never really worn it-even when testing and machining titanium."

Mr. Seek said that his most difficult job so far was to rebuild a 30-ton crankcase. "The unassembled crankcase is very unstable and difficult to clamp. But we still have to machine it to one hundredth of an inch."

NEA does not regret its decision to purchase Droop Rein. The investment has paid off because, depending on the size of the workpiece, the machining time has been reduced by an average of 30% to 40%, and the accuracy has doubled even in critical areas. The tolerance of the bearing race is now only 20 microns instead of 40 microns.

Starrag inspects the geometry of the gantry machine every two years and readjusts it if necessary. "So far, the level of adjustment has been so small that we can actually not use it," Mr. Prell said. 

To ensure that even demanding jobs can be performed accurately, NEA uses sophisticated 2D and 3D laser technology to measure components.

Mr. Seek said that he is happy that he no longer needs to re-clamp the workpiece multiple times during the complete machining of the 50-ton crankcase (GGG-40) made of ductile iron.

In eight years of continuous operation, there has never been a failure, Starrag only needs to replace the ball spindle once. According to Mr. Prell, this kind of replacement is not uncommon for operations that frequently move moving beams.

Although Mr. Prell and his team rarely need to consult Starrag service technicians, they have always been satisfied with their high-quality work. "We have a permanent contact at Starrag who knows us well," said Mr. Prell. "There is clearly a good communication relationship between our employees and Starrag services."  

But can the degree of satisfaction with the Droop Rein T series gantry milling machine be confirmed and summarized? "We prioritize quality, and the portal milling machine is excellent," Mr. Hock said.

"This machine fully meets our expectations," Mr. Prell added. "So far, we have not exceeded the limits of its capabilities."

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