The phased modernization program was carried out by Starrag for a leading aerospace manufacturer producing critical components. While one machine remained in production, the other was stripped back and rebuilt. Once the first machine was proven, the process was reversed, and both Droop+Rein FOGS machines were handed back on time and on budget. For this customer, the economics strongly favored modernization because the machine structures remained mechanically sound and fully integrated into a highly optimized production cell. The project was completed cost-effectively, while also avoiding the significantly longer lead times associated with commissioning a new large-scale machine tool. ”The machine was only down seven months, compared with buying a new machine, which would take around two years. That represents significant cost savings,“ says Starrag USA Service Manager Stephen Barclay. What the customer received was not simply more of the same. Both machines returned with entirely new electrical infrastructure, the latest-generation Siemens CNC, the latest drives and motors, volumetric compensation across the full working envelope, and sensor-level data capture supporting predictive maintenance. The modernization improved reliability, performance, functionality, and visibility while preserving the manufacturing process on which the customer depended. The Droop+Rein FOGS overhead gantry 5-axis machines were originally installed in 2004 and 2011, respectively. ”To give you a perspective, they’re 16 m long, 6 m across, and 2.5 m tall, and they’re designed to machine very large aircraft and fuselage components with very, very high precision,“ says Stephen Barclay, who oversaw the program and coordinated it with Starrag’s engineering teams in Germany. At this scale, precision is expressed volumetrically rather than linearly. ”The target is to position the tip of the cutting tool, which is moving in a 5-axis environment, within a 55-micron sphere anywhere in the working envelope,“ explains Stephen Barclay. Both machines have maintained that precision, or better, through more than 15 years of continuous 24/7 production.

The most demanding requirement was continuity, not speed or accuracy. ”The customer wanted to minimize disruption and internal requalification effort,“ says Stephen Barclay. ”Any significant change to the production platform would have required extensive process validation, programming, and qualification work. A key requirement was that the machine had to run all existing code, use all existing tooling, and integrate seamlessly into the established production environment. By maintaining the proven machine architecture while upgrading the technology platform, we were able to preserve validated manufacturing processes and minimize operational disruption.“

In aerospace, that is not merely a convenience. It is a compliance requirement. ”Aircraft parts are like medical parts. You can’t just randomly decide to build them differently. Every component is serialized. The manufacturing process is proven and carefully controlled,“ Stephen Barclay says.

That principle shaped the technical scope. A completely new electrical cabinet was installed, along with all cables, sensors, and drive modules. Drive motors were replaced with the latest-generation Siemens units, physically smaller, equal in power, and significantly more energy efficient, across two 16 m machines operating around the clock.

The CNC was upgraded to the latest Siemens platform, resolving the obsolescence issue that triggered the project while introducing the latest Sinumerik motion-control packages, including MDynamics and Engineered Motion Control. Spindles and other major mechanical components were deliberately left unchanged. ”It was their decision not to replace the spindles with a different design,“ Stephen Barclay explains. ”They preferred to exchange them for refurbished and repaired versions. This ensured that the critical mechanical components remained in good condition, while avoiding changes that could have affected their process.“ One upgrade went beyond the original project scope. Both machines moved from Starrag’s standard Kinematic Management System (KMS) to Starrag’s upgraded Volumetric Compensation System (VCS), which corrects geometric deviations throughout the machine’s working volume from within the CNC rather than relying solely on mechanical accuracy. The benefits include improved tool-tip positioning during fully interpolated 5-axis movement and enhanced surface quality, exceeding the equal-to-or-better performance standard Starrag was contracted to achieve.