Software Solutions
Keeping Pace with Aerospace Challenges
Requirements for Machining Machining of aerospace components requires excellence by the manufacturer to adopt and carefully follow procedures to ensure quality, repeatability and traceability. The components required in this industry have very stringent and varying requirements. Structural components must be lightweight, generally made from aluminium or composites (may have moulds from aluminium). Engine components and landing gear are generally made of titanium, steel or nickel- based superalloys. These materials focus on strength and temperature resistance. For engine components, titanium is used where possible as the material density is nearly half that of steel or superalloys. It also helps to control weight. High-performance roughing is necessary to bring aluminium blocks or plates to a near-net shape. Up to 90% or more of the block weight may be removed during roughing processes. Not only is this important in typical 3-axis structural compo- nents, but it is equally crucial in 5-axis compo- nents. Many CAM software programs have a high-performance roughing module. Here, OPEN MIND offers its hyperMILL® MAXX Machining roughing module. This machining approach is based on Celeritive’s Volumill™ kernel but has been extended by OPEN MIND to have an ap- plication for 5-axis roughing. In cases of shaped structural components (some wing segments Machining Strategies for Structural Components
It’s clear to see that aerospace industry component manufacturing is in a large growth cycle. Advancements in materials and engine efficiency have created clear benefits for replacing a surplus of older aircraft equipment, these advancements cover both the engine and structural components. As wonderful as this is the demand is so significant that machine tool manufacturers are challenged to supply the equipment fast enough. Increasing productivity is key. There are many CAM software products available and most of these have targeted capabilities. The focus may be on a process such as 5-axis milling, mill/turn, or wire EDM. Or the CAM software may be optimal for applications such as mould and die or aerospace applications. Not many aerospace machining companies, especially tiered vendors, machine all types of aerospace components. However, some do and certainly, aerospace OEM companies tend to machine a wide array of aerospace parts, even if only for development components. Therefore, the ideal CAM software for aerospace manufacturers has to excel at high material removal rates and the machining of aluminium structures whilst working well with high precision requirements of compressors and turbines that are often machined with long slender tools.
“hyperMILL MAXX Machining and conical barrel cutters enable a large contact radius and clearance from wall surfaces”
for example or doors), a 5-axis roughing process provides a huge benefit to subsequent machining processes. Following high-performance roughing operations, innovative finishing techniques can have a big impact on results. The surfaces of standard structural parts are machined with a swarf milling operation, with the side of the cutter aligned to the side of the part. This process enables very good performance, but it is limited to ‘short’ wall surfaces typically up to 50mm in height. For larger wall surfaces, the swarf milling operation may lead to vibration in the cutter or the wall surface, or multiple steps with overlap and inconsistent deflection patterns. In these cases or other cases that do not have ruled surface walls, the next best option is point milling in many passes by using the tip of a ball-nose endmill with a small step-over. This point milling method increases cutting time dramatically. Recent innovations include applying barrel cutter geometry to these surfaces. OPEN MIND’s hyperMILL MAXX Machining
finishing approach uses a conical barrel cutter to enable a barrel contact radius of 1000mm or more, thereby producing a wider step-down of 10 to 15 times compared to that of a ball-nose endmill. This enables the cutting time for these surfaces to be reduced by 90% or more. The conical barrel cutter has a large barrel radius ground on a tapered feature, compared to a traditional barrel cutter where the large radius blend is at a tangent to the cutter shank. The benefit of having the taper angle is that the tool axis can be pulled away from the surface being cut. The result is a shorter and stiffer set-up without interference from the cutter holder. The machining benefits far outweigh the increased cost of conical barrel cutters, especially in aerospace production applications. Though the tangent barrel cutter provides some benefits, the conical barrel cutter is generally superior to enabling a larger barrel radius and allowing shorter cutters without interference from the cutter holder. Conical barrel cutters exhibit long tool life and very consistent machining performance. In Machinery & Manufacturing 49
Machinery & Manufacturing 48
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