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One speci c area of application is in airframe manufacture. Many com- ponents are made currently by machining from a solid billet or forging, but over 50% of the original stock is lost as swarf. Another area under consideration is landing gear production where a cost saving of 70% is expected by using additive manufacturing.
Current Activity
Additive layer manufacturing offers several advantages for certain structural components such as a vast reduction in material wastage, especially when producing many heterogeneous parts, and the ability to produce a great variety of part designs for prototype work quickly.
There is also the key bene t that it allows the consideration of uncon- ventional designs that otherwise would not be practical because of manufacturing or cost constraints due to, for example, complex or unusual geometries, bringing with it many different opportunities and challenges.
Early work at Cran eld University for Rolls-Royce targeted aero engine applications. Researchers here developed the wire + arc deposition process to examine the use of Inconel, titanium, aluminium and various nickel alloys. Since then the focus has shifted to airframes. Although laser and powder methods are useful for certain applications such as rapid prototyping or for small highly complex parts, this technology is limited by its speed and the size of component it can accurately man- ufacture. In contrast, the processes being developed at Cran eld are designed for high deposition rates.
To put this difference into context, the Cran eld centre is currently tar- geting a deposition rate of 10 kg/hr, compared with a typical 0.1kg/hr using laser + powder methods, which can also potentially carry the risk of the material not being fully consolidated if fusion has not occurred between grains. Additive arc + wire systems are also capable of produc- ing parts several metres in size and simplify the process of producing single piece linear intersections.
The Damen Shipyards Group entered a cooperative consortium with RAMLAB, Promarin, Autodesk and Bureau Veritas to develop rst class approved marine propellers.
The early work terminated in the production of the world’s rst WAAM manufactured propeller in 2017 [8]. It is based on a Promarin design typically found on a Damen Stan Tug type 1606 [Figure 5].
Cost of Equipment
Powder deposition technology requires a substantial metal enclosure within which all the operating system including laser (or electron beam) heat source, computer numerical control equipment and powder dispensing. A typical cost of a production system is $750,000. Wire deposition is undertaken with standard arc welding equipment coupled with a 5-axis articulated robot costing a total of $120,000. [9]
Cost of Consumables
Only a limited number of metallic alloy systems are currently available for additive manufacturing using powders principally Ti-6Al-4V, some stainless steels, Inconel 625/718, and Al-Si-10Mg. The cost for many
Figure 4. Main structural element of aircraft wing.
Technical Papers
Figure 5. 1300 mm, 180 kg Bronze Propeller
ITAtube Journal No2/May 2019
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