While fuselage panels continue to increase in size and complexity, factors such as tighter tolerances and higher aircraft build rates are prompting a rethink about the optimal production process for these critical structures. For aerospace manufacturers, the challenge extends far beyond material removal alone. Every decision must now balance precision and throughput with cost and sustainability.
Although chemical milling has played a central role in fuselage panel manufacturing for decades, advances in digital machining are presenting a far more attractive alternative, with production time and energy usage savings of up to 65% and 50%, respectively.
The evolution of high-accuracy mechanical machining for use on fuselage panels reflects ‘precision at scale,’ the ethos of Fives High Precision Machines (Fives HPM) that underpins its newly unified brand portfolio. Marrying a broad range of advanced machining and manufacturing technologies under a single identity, Fives HPM blends engineering expertise with an established U.S. network of production facilities and customer support teams to help the aerospace sector overcome core challenges.
An example is the Mirror Milling Star (MMS), a digital machining solution developed specifically to replace conventional chemical milling in the production of large aluminum or composite fuselage panels.
While chemical milling is largely limited to pocketing operations, the MMS performs high-speed milling, drilling and trimming on a single platform. Manufacturers benefit from greater flexibility, fewer process steps, significantly improved productivity and a more circular production process in terms of recycling opportunities - all while maximizing dimensional precision.
Beyond Chemical Processes
Chemical machining has served the aerospace industry well, but its shortcomings are increasingly difficult to ignore. The process depends on hazardous chemicals that require specialist storage, handling and disposal, creating environmental obligations alongside higher operating costs. Offering relatively little flexibility, chemical milling also occupies considerable factory space and consumes high amounts of electricity.
MMS removes many of these constraints while simultaneously expanding manufacturing capability. Notably, the system leverages intelligent digital technologies to adapt every machining cycle to the actual geometry of individual panels.
The result is a process that delivers consistent accuracy, even when machining large, thin-walled aerospace structures with complex 3D contours.
Fives Group
Adaptive Digital Precision
The foundation of the system is advanced surface scanning capability that measures the real shape of every formed panel before machining commences. Rather than assuming each panel perfectly matches its CAD model, the machine recognizes that forming processes inevitably introduce minor variations. Capturing those differences at the outset supports automatic compensation routines during machining.
Fives' proprietary Scan & MAP (Milling Adaptive Process) is the facilitating technology. After a high-resolution laser scan, software reconstructs the panel's true geometry, morphs the theoretical machining program to match the measured surface and automatically generates the optimal tool path. Instead of forcing the panel to conform with an idealized model, the machining program adapts to the actual geometry.
This distinction is vital when producing large aircraft skins, where maintaining highly accurate pocket depths directly influences both structural performance and aircraft weight. Through dynamic adjustment of the machining path, manufacturers can achieve exceptional dimensional accuracy.
12-Axis Synchronization
A key differentiator of MMS is its patented mirror machining architecture. Two synchronized six-axis heads operate simultaneously on opposite sides of the panel. One incorporates the high-speed electro-spindle, while the second provides continuous panel support. By maintaining contact with the workpiece throughout the machining cycle, it becomes possible to minimize vibration and maximize stability.
Together, the 12 synchronized axes respond dynamically as machining progresses, with an ultrasonic sensor continuously measuring the remaining material thickness. This capability enables the system to verify pocket depths in real time rather than relying exclusively on post-process inspection. The combination of adaptive machining, active support and continuous measurement is powerful for manufacturers: It provides control over panel symmetry and wall thickness, regardless of geometry.
The machine also replaces conventional dedicated fixtures with flexible universal holding frames that accommodate multiple panel designs without introducing workpiece stress. Besides reducing tooling investment, this approach simplifies panel handling and permits the machining of both panel sides without unclamping. The outcome: better repeatability and less non-cutting time.
Fives Group
Connected Manufacturing Intelligence
Digital advantages extend far beyond the machining operation itself. Rather than functioning as a stand-alone machine tool, MMS forms part of a connected manufacturing environment encompassing programming, production, inspection, process analysis and continuous improvement.
Dedicated Fives software simplifies programming by automating many previously manual operations and driving substantial reductions in set-up time. During machining, the system simultaneously records tool position together with quality and process data, creating a 3D digital representation of the finished panel as production progresses.
This information flow provides valuable insight into both product quality and machine performance. Integrated inspection capabilities reduce reliance on separate measurement routines, while secure data collection supports predictive maintenance, traceability and broader Industry 4.0 initiatives.
Savings and Sustainability
Compared with chemical milling, manufacturers can reduce production time by as much as 65% while cutting factory floor requirements by around half. Electricity consumption also witnesses major reductions, typically up to 50%, lowering both operating costs and carbon emissions.
Further environmental benefits include eliminating the need for storing, transporting, treating and disposing of chemicals. Instead of generating hazardous, unusable sludge, MMS produces aluminum chips for recycling, creating additional revenue.
Perhaps equally important is the breadth of applications supported by the technology. In addition to fuselage panels, MMS has proven its capabilities on aircraft canopy structures, landing gear reinforcements and complex waffle components used in space launch vehicles.
Precision at Scale
Originally developed in collaboration with Airbus and continuously refined over more than two decades, MMS systems are now producing tens of thousands of fuselage panels every year for aerospace manufacturers worldwide.
