Precision manufacture of concrete parts using integrated robotic 3D printing and milling

When manufacturing free-form concrete parts, casting approaches are most commonly adopted. While casting allows good surface finish, geometric repeatability and easy replication of parts, it is inflexible and costly to setup. Expensive mould tools, with limited life, must be created before manufacturing can begin. These mould tools must then be safely stored to ensure future identical parts can be manufactured. If damaged, recreating exact replica mould tooling is an expensive and time-consuming process. The cost and difficulty of manufacturing new tooling therefore prohibits the economic manufacture of many bespoke parts, or results in significant lead time increases and project delays. An alternative approach, that is gaining increasing interest, is the use of 3D printing for concrete. A robot is used to guide a concrete deposition nozzle in a layer by layer deposition path, similar to polymer fused deposition modelling. However, in Concrete 3D Printing the combination of complex material rheological properties, and the need for high volumetric deposition rates, means achieving net shape precision parts from the deposition step is extremely challenging. To address this issue, a hybrid robotic 3D printing and milling system has been developed, with integrated in-process structured-light metrology, to enable the production of precision concrete parts with well controlled geometric features. The integrated robot manufacturing cell is described. Examples structures that demonstrate the ability to create and replicate complex concrete parts with improved surface properties are illustrated. Components with surface features that enable concrete assemblies are studied to illustrate the capability of the hybrid process to manufacture challenging parts with demanding geometric requirements. These structures are used to quantify the performance of the current system and illustrate the future potential for the approach.