An Introduction to Wire Arc Additive Manufacturing
17 May 2018
Wire Arc Additive Manufacturing (WAAM) is a large-scale metal AM technology that uses an arc welding process to produce metal parts additively. While WAAM is one of the lesser-known metal AM technologies, it offers a viable alternative to traditional manufacturing, with a wide range of use cases in industries such as aerospace, marine, automotive and architecture.
This tutorial will focus how Wire Arc Additive Manufacturing works, its benefits and limitations for industrial applications, as well as existing use cases.
How does Wire Arc Additive Manufacturing work?
Unlike the more common metal powder AM processes, Wire Arc Additive Manufacturing works by melting metal wire using an electric arc as the heat source. The wire, when melted, is then extruded in the form of beads on the substrate. As the beads stick together, they create a layer of metal material. The process is then repeated, layer by layer, with a robotic arm, until the metal part is completed.
WAAM can work with a wide range of metals, provided they are in wire form. This list includes stainless steel, nickel-based alloys, titanium alloys and aluminium alloys.
The Benefits of Wire Arc Additive Manufacturing
WAAM offers several benefits, with the potential to enhance metal additive manufacturing across industries.
- WAAM is particularly suited to manufacturing large-scale metal parts, in contrast to powder-based metal AM technologies, which typically produce smaller, high-definition components. Unlike powder-bed AM processes, which have a limited build envelope, the robotic arm of a WAAM machine has more freedom of movement, meaning that the size of a component isn’t limited by space, but only by the distance the robotic arm can reach. This allows for the production of larger parts, which wouldn’t be possible with powder-bed processes.
- In terms of material costs, the welding wire used in the WAAM printing process is significantly less expensive than the metal powder used in powder-based metal AM. This is because WAAM technology is based on welding, a well-established manufacturing technology in and of itself. WAAM hardware usually includes off-the-shelf welding equipment, which is less expensive than many metal 3D printers available on the market.
- Unlike subtractive methods, WAAM uses a layer-by-layer approach to create a component. This means that material is deposited only where it’s needed, resulting in significant material savings and reduced material costs.
- WAAM technology can deliver near net shape components, minimising the need for surface finishing. Parts produced with WAAM are particularly notable for their high density and strong mechanical properties, comparable to those manufactured with traditional manufacturing methods.
- WAAM is also a good option for repair and maintenance operations for specific components like turbine blades, and also moulds and dies. Worn-out features or damaged parts can be repaired with WAAM by depositing new material on its surface. This can result in significant cost savings as it eliminates the need of producing a new part from scratch.
The limitations of Wire Arc Additive Manufacturing
- Although a number of companies are developing WAAM technology for the production of metal parts, currently there is no commercially available system. However, collaborators such as Kuka Systems, Airbus Defence and Space, FMC Technologies and other companies are currently working to develop a systematic methodology for WAAM.
- Heat management is another challenge associated with WAAM. The printing process involves high temperatures, causing build-up of residual stress — a problem commonly faced with metal 3D printing. As residual stress can often lead to deformations in a component, cooling must be factored into the process.
- When using certain materials, like titanium, shielding is necessary to create an inert atmosphere to ensure the right building conditions, meaning that the process has to take place in an inert gas chamber. However, the inert gas chamber limits the size of parts that can be produced with this technology and installing such chamber will increase the cost of the equipment.
Current applications of Wire Arc Additive Manufacturing
A number of industries are currently leveraging the benefits offered by WAAM to create large components with strong mechanical properties.
Aerospace is one of the main industries that is currently unlocking the full potential of WAAM. For aerospace applications, WAAM can be used to produce large structures such as stiffened panels and wing ribs, making the overall manufacturing process more sustainable and cost-efficient. For example, aerostructure manufacturer, STELIA Aerospace, has recently created aluminium fuselage panels with stiffeners manufactured directly on the surface, using the WAAM technology. And with STELIA Aerospace also exploring the possibility of integrating WAAM with topology optimisation, we could be seeing more disruptive benefits of WAAM within the aerospace industry.
Another example of WAAM being used to produce large components is with the the world’s first 3D printed ship’s propeller. The “WAAMpeller” uses 298 layers of nickel aluminium bronze alloy and was completed in seven months — demonstrating the potential of WAAM to optimise the production of future vessel components.
As the construction industry opens up to the advantages of additive manufacturing, WAAM can also be used in architectural applications. Take for example, MX3D’s steel bridge, which was constructed thanks to the multi-axis WAAM technology and showcases the freedom of design provided by additive manufacturing.
To sum up
As additive manufacturing steadily moves towards the production of large metal components, large-scale AM processes like WAAM are increasingly feasible. Wire Arc Additive Manufacturing certainly holds the potentially to transform the way large metal components are produced, paving the way for a more cost-effective method of manufacturing large-scale metal parts for demanding industrial applications.