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Hybrid additive manufacturing for the built environment

Innovative building designs often present significant technical challenges to engineers, and require costly, custom-made components. Additive manufacturing, commonly known as 3D printing, provides a promising way forward as it offers great geometrical flexibility. However, so far, the use of additive manufacturing technology in the built environment has been restricted due to its high costs and long production time compared with conventional fabrication methods.

We have undertaken research on integrating 3D printing with investment casting to produce building components of forms that would otherwise be very difficult to manufacture due to level of technical complexity or financial constraints. Through this hybrid additive manufacturing approach, the geometric flexibility of 3D printing can be combined with the technical familiarity of investment casting. In this way, customized components can be batch produced cost effectively in a large selection of metals and alloys.

The research was successful in replacing wax mould in a standard casting facility with 3D-printed Polyvinyl alcohol (PVA) and Polylactic acid (PLA) ones.

Newly produced moulds were then applied to produce metal component with the same dimensional accuracy and structural integrity as other investment casted piece. This means that complex components can be batch produced at a comparable cost as a standard investment casted component in a large selection of metals and alloys.

Using the proposed hybrid manufacturing method, complex building components, which are sometimes produced by welding pieces of metal together, can be manufactured as a single casted piece at a relatively comparable cost to the traditional methods.

The proposed hybrid additive manufacturing method was applied in a high-profile stadium project in Japan, where it enabled engineers to deliver a more innovative structural component designs. The application of the approach can be extended to façade components or topologically optimised components that have complex geometries.

Through this research, next step towards the cost-effective use of topological optimisation in projects was made. This, in turn, is expected to enable bold architectural designs to be delivered, not limited by the manufacturing capacity for sophisticated details. For business-as-usual undertakings, the research encourages engineers to deliver optimised designs by adopting variations in components.