Unparalleled variety with 3D printing

Rethinking traditional manufacturing

The design of a bronze statue 6 metres high and almost 8 metres wide required the expertise of architects, engineers and craftspeople. The preferred manufacturing process for bronze sculptures is investment casting. Traditionally, a true-to-scale model is moulded from clay and cast in silicone. This is then reproduced in wax to create a ceramic mould into which bronze is poured. A complex and labour-intensive process that can be significantly simplified by 3D printing. PMMA 3D printing, in particular, is revolutionising this process.

As with other 3D printing technologies, the design is created digitally. Artists are increasingly using digital design technologies to gain greater creative freedom and make changes more easily. CAD design was also used to create a digital model for the Boston Common sculpture. The Walla Walla Foundry in Washington, renowned for its expertise in art casting, was selected to produce the sculpture. Using two VX1000 PMMA 3D printers from voxeljet, they complemented traditional foundry technologies with modern 3D printing processes.

The ideal complement to traditional foundry technologies

At the Walla Walla Foundry, the CAD files were scaled and broken down into 608 individual parts, which were then produced on the VX1000 Binder Jet 3D printers. This technology enables optimal use of the build volume whilst ensuring the highest precision. In addition, a complete model of the sculpture was printed to check the proportions and handling.

The 3D printers utilise binder jetting technology. The digital CAD file is broken down into thin layers, which are selectively printed using PMMA powder. Once completed, the parts are cleaned and post-processed, for example by infiltrating them with wax to achieve smooth surfaces. The PMMA models are treated in the same way as conventional wax models: once the ceramic shell has been constructed, the PMMA is melted away and replaced with bronze. The individual parts were welded together and patinated; the final statue, including the framework, weighs 19 tonnes. The entire production process took two years.

How 3D printing is ushering in the future of sculpture

Today, ‘The Embrace’ stands in Boston Common as a testament to justice and progress. It is not only a symbol of the legacy of Martin Luther King and his family, but also an example of the precision and efficiency achieved by combining modern 3D printing technology with traditional art and investment casting. This technology enables artists and architects to realise monumental visions without being constrained by the limitations of traditional casting methods.