Processing Knowledge to Optimize Aerospace Frame Production
By Michael Standridge
Aerospace Industry Specialist
Fair Lawn, NJ
By all accounts, aerospace manufacturing is entering a boom cycle. The existing global fleet is aging; simultaneously, emerging markets are ramping up the demand for new aircraft. All the while, the frequency of technological advancements is accelerating, speeding up obsolescence and shortening the useful lives of air fleets across markets.
What will differentiate OEMs in this smorgasbord of business will be their ability to best deliver in the face of increased demand. Among many other measurements, aerospace manufacturing can be measured in feet per day. If an aircraft is 150' (46-m) long, then a line would have to move at 150' per day to hit one plane per day—which may be too lofty a goal, but is a useful metric: It hightlights the need for efficiency in order to optimize processes and squeeze as many inches out of a line as possible. Even in manufacturing massive structures like airframes, it really comes down to a game of inches.
And aerospace has a unique set of circumstances that forces OEMs to constantly be able to adapt. With difficult-to-machine new materials and complex geometries, aerospace structural components require total machining solutions, from tooling selection and application to spindle interface. These solutions need to meet the tightest of tolerances, as air travel safety exists in the balance between microns. Meeting such high demands requires more than the right equipment and tooling; it requires the processing knowledge that will optimize every step of the machining process and the impact of the cutting tool.
Holemaking: With thousands of holes in every aircraft, optimizing the holemaking process in aerospace machining is essential in achieving top efficiency at the closest tolerances. Considerations in both tool selection and application are important for optimal success, speeding up that inch-by-inch movement down the line.
Achieving top hole quality is challenging when it comes to machining carbon-fiber and titanium- or aluminum-stacked materials, all commonly encountered in aerospace manufacturing. Stacked materials are common in frame components, but the difference in material properties comes with its own set of demands.
Fiber splintering, for example, is a common occurrence when drilling stacked materials. The CoroDrill 854/856 is designed with a unique point geometry and diamond coating to reduce splintering and burr formation on exit. A small point angle and high rake angle also help reduce axial forces.
Process security: Choosing the right machine tool interface is just as important, if not more so, than choosing the right tooling. Without an interface that will deliver superior process security, the entire machining process is at risk. Coromant Capto provides simultaneous face and taper contact for improved accuracy and strength in all application areas of frame machining: milling, drilling and turning. It also has the flexibility to optimize the length required to keep maximum stability and radial runout, in high metal removal.
CAM programming: Today, CAM programming has a tremendous impact on manufacturing productivity. The advanced software options are vast, from 3D modeling CAD systems to CAM systems that read and interpret CAD models for easy machine programming.
The toolpath can impact the cutting tool as much or even more than the spindle and machine tool. While the spindle and machine tool must be properly designed and possibly even customized for efficient machining of aerospace alloys, machining productivity comes from removing metal in the cutting zone.
Optimized toolpaths occur by controlling and maintaining cutting tool position, as a percentage of the diameter of the tool engaged into the workpiece and that engagement’s effect on feed rate. This is the foundation for both productivity and machining security. The key to successful, low-cost machining is having a CAM system that can adapt to the complex features of aerospace components while maintaining optimized parameters.
Aerospace alloys are designed to retain strength under load forces and heat while resisting corrosion and fatigue. The elements and processes that create these alloys make them difficult to machine securely and consistently at a high productive rate. The challenge today is for machine tool systems, cutting tool systems and CAM systems to be optimized and applied to support each other in order to achieve high performance output—increasing productivity, and controlling production costs. ✈
This article was first published in the 2013 edition of the Aerospace & Defense Manufacturing Yearbook.
Published Date : 12/10/2013